Star app for android


The recently released book “Dark Skies: A Practical Guide to Astrotourism” lists sites around the world where people can see the stars without light pollution.

Here & Now’s Jeremy Hobson speaks with author Valerie Stimac (@Valerie_Valise).

Book Excerpt: “Dark Skies”

By Valerie Stimac


When the cloudy expanse of the Milky Way stretches above us from horizon to horizon, or a meteor streaks across the sky, or a rocket defies gravity to leave earth, it touches on a sense of wonder and awe. There is something breathtaking and humbling about the knowledge that beyond the protective layer of our atmosphere, there is a lot more out there. The universe is vast almost beyond comprehension: while technology helps increase our knowledge of moons, planets, and suns, we can hardly imagine how many other places there are in our solar system, galaxy, and the universe once you leave planet earth.

The natural world on earth never ceases to amaze us; we make pilgrimages to Everest, Niagara, the Amazon, and countless other awe-inspiring sites on our bucket list. But somehow, the night sky is often omitted from the list of natural experiences we should seek out. Yet its magnificence can be even more overwhelming than terrestrial wonders. For millions of years, the stars have wheeled overhead, and the planets have performed their celestial dance. Observing this pageant used to be a nightly ritual for humans across the planet each night until very recently. But while we often book trips to explore new cities and try new foods, we rarely do the same for astronomical phenomena and space experiences. We may have gone stargazing as a kid or learned about astronomy in school, but we don’t journey to discover it first-hand. Yet according to a 2016 atlas by the Light Pollution Science and Technology Institute, 99% of the populations of Europe and the US no longer have access to the night sky due to light pollution. In not seeking out encounters with astronomical phenomena, whether at the certified dark sky parks listed in this book or by viewing a meteor shower or eclipse, we deprive ourselves of a magical experience.

What drives our collective interest in the night sky? It’s likely the case that the roots of astronomy lay deep in the prehistoric era, among the first homo sapiens who became aware that the movements of the sun, moon, and stars were not random. In an attempt to find significance among these patterns, religious beliefs were established to help make sense of the natural phenomena. These religious beliefs remain closely tied to astronomy to this day, as reflected by practice of astrology (the idea that the movement and placement of stars and planets have a direct impact on our daily lives).

Author Valerie Stimac (Courtesy of Stimac)

A more modern interpretation might also say that though we did not always know with scientific certainty that there was ‘more’ beyond earth, our human nature to explore and colonize drives us to look toward the stars. In the 21st century, it’s likely that our efforts and investment will take us to other planets in our solar system at the very least. While we have spent centuries learning about the night sky, our time exploring it has only just begun.

The most easily accessible way to enjoy the night sky is by stargazing, looking up at the constellations and planets visible either with the naked eye or through a telescope. Astronomy dates back nearly 5,000 years, to the Bronze Age. While there aren’t many records from this time, archaeoastronomers have discovered evidence and relics that suggest that from among the earliest periods in human history, we were attentive to the night sky and attempted to record the patterns observed there. Nearly every major civilization at one time was involved in the study of astronomy. Major sites testifying to the astronomical knowledge of earlier cultures remain in the Yucatan, at Uxmal and Chichen Itza; at Chaco Canyon; and at the pyramids of Egypt, Stonehenge, and more.

Early contributions by civilizations like the Sumerians, Babylonians, and Indians are still used in astronomy today. Over the centuries, the amalgamation of work by Chinese, Islamic, Egyptian, and European astronomers helped solidify astronomy into a scientific field in its own right. During the medieval era, astronomy was advanced significantly by the work of Islamic astronomers. While astronomy was actively practiced in Asia, Islamic astronomers helped with the translation from ancient Greek to Latin of fundamental astronomy texts by thinkers including Aristotle, Euclid and Ptolemy. As a result European astronomers were able to recommit to the science of astronomy that was at risk of being lost. Islamic astronomers also created some of the most accurate calendars, predictive models, and recorded observations of astronomical phenomena in human history.

Later, Renaissance astronomer Nicolaus Copernicus helped initiate the Scientific Revolution which fundamentally shifted human understanding of astronomy and science in the 15th and 16th centuries. While the idea of a heliocentric universe had been proposed centuries before by the Greek astronomer Ptolemy, Copernicus’ reassertion that the earth orbited the sun became one of the most controversial ideas of human history. Physicists and astronomers including Galileo, Kepler, and Newton helped drive forward our understanding of the universe using this new model.

After initial resistance by the Catholic Church, the Copernican theory was accepted and knowledge about astronomy and astrophysical principles began to receive global consensus. The Copernican revolution came to its natural conclusion with the discovery of a series of scientific laws that helped us understand the night sky and our place in it. Between the 17th and 20th centuries, the rate of discoveries by observational astronomers increased exponentially as the astronomical objects and phenomena laid out by these new laws was confirmed. Findings included the discoveries of planets, moons, asteroids, and comets in our solar system as well as more distant galaxies, nebulae, exoplanets, and black holes. New observing technology developments accelerated our rate of discoveries too. First invented in 1608, simple telescopes became increasingly powerful at observing the heavens. While there continued to be disagreement in reconciling religious and scientific beliefs about the solar system and universe, these were for the most part relegated away from the steady advancement of human knowledge of planets and moons, asteroids and comets, nebulae, supernovas, and galaxies.

During the 20th century, massive strides were made to improve astronomical technology for observing the skies, and our theoretical understanding made similar strides after Einstein’s breakthroughs around General and Special Relativity. The light we see from the stars and planets has to travel across space to reach earth; as a result, understanding how light moves is fundamental to understanding Building on the massive legacy from civilizations and centuries of astronomy, scientists have been able to ask the deepest questions about the origins of the universe – and have begun to craft answers based on the observational data and theoretical models we have developed. As the 21st century continues, we are closer than ever to understanding the night sky, but still have a lot we don’t even know to ask. When we look up at the stars and galaxies in the night sky, we are seeing the death of old stars in supernova, the birth of new ones in stellar nebulae (also sometimes called ‘nurseries’), and in some cases, the impacts of invisible-to-use black holes on the space around them.

Even the space race of the 20th century was in part driven by the pull we feel to reach the stars. Milestones such as putting the first man in space or reaching the moon were meaningful because they took significant steps beyond our planet – the place we have called home for millennia. The human race to space has continued to launch satellites, orbiters, space telescopes, and rovers to explore deeper into space to better understand how the universe works.

The latter half of the 20th century and early 21st century has also seen the rise of the dark sky preservation movement. Driven by international organisations like the International Dark-Sky Association, national bodies like the Royal Astronomical Society of Canada, and local institutions and advocacy groups, there is an increasing focus on preserving the dark sky where it is still visible, or in some cases reverting back to darker skies through infrastructure planning and lighting replacements. Many of the locations mentioned in this book are destinations focused on dark sky preservation, and some have received designations for their work preserving the darkness. If you think you’ve seen the night sky but you’ve never witnessed it from a location with a truly dark sky, you’re in for the surprise of a lifetime.

The skies above us are part of our heritage, both natural and cultural. Astronomy and stargazing are an important part of human history, one that can connect us back to early myth or awaken us to the vast scale of our Universe and its many mysteries. Witnessing the sweep of the Milky Way, the remains of passing comets as they burn up in our atmosphere, or the shimmering aurora, we better understand space and our place in it. his book will help you experience all of this and more first-hand, so that you can glimpse some of the celestial wonder yourself.. Whether you visit a professional observatory, take part in Space Camp, observe a meteor shower, or merely spot the constellations above, your journey will deepen your knowledge and appreciation for our planet and the universe as a whole.

How to Use this Book

This book is divided into sections based on whether it’s about witnessing the dark sky at a specific preserve, observing a natural phenomena such as a meteor shower, eclipse, or the aurora up close, or travelling to a major telescope or laboratory. You can even explore the options for suborbital space flight! Alternatively, maybe you won’t be travelling anywhere but up, by looking at the heavens directly in your backyard. In each section, you’ll learn about different space-related activities, then gain an understanding of where and how to have that experience.

Stargazing focuses on the basics of appreciating the dark sky. In it, you’ll find an overview on how to stargaze and what types of objects you can look for in the night sky. You’ll also find tips on urban stargazing, which most people can do no matter where they live There’s information on getting more involved with stargazing communities, including by joining astronomy clubs, visiting observatories, and attending star parties. You’ll get some tips on how to shoot astrophotography and how you can give back through citizen science that uses the support of ordinary people on earth to analyze and answer some of our biggest questions about space.

Dark Places is devoted to highlighting 35 of the best places around the globe for stargazing and experiencing the night sky. While this section is far from exhaustive, it includes locations across the globe that are designated dark sky places. These designated places take additional measures to reduce light pollution and ensure that if the skies are clear you’ll see the stars (nothing can help you overcome a cloudy night, alas). There are also dark places in this section which do not have a formal designation but which possess a special attraction for stargazing and astrotourism.

Astronomy in Action focuses on destinations and experiences where you can get a closer look at space science. In this section you’ll recognize some of the world’s top research facilities and observatories. Most of these locations are open to the public (though often on limited schedules) meaning you can plan to visit them on a trip to the area – or even make astronomy the sole focus of your trip.

Meteor Showers has everything you need to know about some of the most consistent and impressive meteor showers of each year. Meteor showers occur throughout the year on a regular schedule star.’ You’ll learn about the science behind meteor showers, when they occur and nights of peak activity, and where to look in the night sky to try and see meteors.

Aurora is devoted to another breathtaking astronomical phenomena: the aurora. The section is subdivided into two parts, focusing on the aurora borealis in the northern hemisphere and the aurora australis in the southern hemisphere. You’ll get guidance on where to see the aurora in each country where they commonly occur, plus some tips on other destinations where it’s possible (but rare) to see the aurora.

Eclipses is devoted to the science and schedule of total solar eclipses in the next decade so you can plan your trip and become an eclipse chaser. You’ll learn about where the path of totality will occur for each eclipse plus how to get there and what else you can experience in the region once the solar eclipse is over.

Launches helps you experience a different side of astrotourism: rockets. Countries around the world are actively launching rockets to send instruments, supplies, and humans to space, and you can travel to launch locations around the globe.

Space Tourism discusses the future of humans in space–including you! In this section you’ll learn about the major players in the rapidly evolving space tourism market, plus some of the common destinations and experiences for going to space.

In the Appendices, you’ll find additional resources on some of the topics covered in other sections of the book. You’ll learn about the Bortle Dark Sky Scale, which helps scientists understand how dark the sky is in different areas–and you can find out how dark the sky where you live. There’s also an extended schedule of eclipses to help you plan your eclipse chasing adventures.

This book is not an encyclopedia of astronomy or the comprehensive guide to all space-experiences in the world. There are many places not listed here where you can enjoy the aurora, see meteors and stars in a dark night sky, and even marvel at the human ingenuity that is making us an multi-planetary species. Instead, use this book as inspiration. Let it spark an idea that you can enjoy your next destination after the sun goes down, add on a few extra days for one of these experiences, or plan a trip to enjoy the night sky anywhere in the world.

Excerpted from “Dark Skies: A Practical Guide to Astrotourism” by Valerie Stimac. Copyright © 2019 by Valerie Stimac. Republished with permission of Lonely Planet.

What’s a black hole? What will a larger aperture telescope get you? This is the place to come for answers to almost every astronomy question you can think of — and many you haven’t.

Science-Based Q&A

Deepen your knowledge of astronomy as a science as you browse these Q&As and learn about the universe’s fascinating array of celestial bodies, from planets to stars to black holes. Discover the difference (and evidence for) dark energy and dark matter, and learn about worlds closer to home such as Venus and Saturn.

Solar System


  • How big is the Sun?
  • What is the solar wind?
  • When will the last total solar eclipse occur?


  • How many planets are in our solar system?
  • What are the smallest and largest planets in our solar system?
  • Why do the outer, gas-giant planets rotate faster than the inner, terrestrial planets?
  • Will all eight planets ever line up on the same side of the Sun?
  • Is there any other planet besides Earth whose moon(s) would fit perfectly over the Sun?
  • What happened to the “spokes” in Saturn’s rings?
  • If you lived on Saturn, would its rings be visible from the equator or the poles?
  • What determines a moon’s atmosphere? (Why is Titan’s so dense?)

Comets, Asteroids & Meteors

  • What is a comet? Where do comets come from?
  • What are asteroids and where do they come from?
  • What is a meteor shower?
  • Why do comets have tails?
  • Why are comets and asteroids discovered when they are farthest from the Sun?
  • How large an asteroid could a person jump off?
  • How much space debris falls into Earth’s atmosphere every year?
  • If asteroid 99942 Apophis ever strikes Earth, how big would the crater be?
  • Will asteroid 99942 Apophis eclipse the Moon when it passes by?


  • How did the universe begin? What happened during the Big Bang?
  • What came before the Big Bang?
  • Where was the Big Bang located?
  • Is there a center of the universe?
  • Is space flat or curved?
  • How do we measure a galaxy’s distance?
  • What is dark matter?
  • What is dark energy?
  • How fast is the universe expanding?
  • Is the universe infinite?
  • What is the age of the universe?
  • The end of the universe: What is our ultimate fate?


  • How many galaxies are there in the universe?
  • Is it true that Andromeda Galaxy is moving toward us?

Milky Way

  • How many stars are in the Milky Way?
  • What percentage of our galaxy’s stars move in retrograde orbits?

Black Holes

  • What is a black hole?
  • What’s inside a black hole?
  • Are black holes real? If so, who discovered them?
  • How big is a black hole?
  • How do black holes form?
  • How does time change inside a black hole?
  • What would happen if I fed antimatter into a black hole?
  • What’s the density of a black hole?
  • More black hole facts


  • What is a star?
  • Why do stars twinkle?
  • Why are the stars so far away?
  • How far is the closest star?
  • What is the brightest star in the sky?
  • What are constellations?
  • How can we find the Sun’s place among the constellations?
  • What’s the distance to Polaris?
  • How can binary stars orbit each other so fast?
  • How long do stars live? How do stars die?
  • How many stars are there in the universe?
  • Why are there no green stars?
  • How do astronomers accurately determine wobbles in a star’s motion?
  • If you combine the magnitudes of all visible stars, how bright a star will you come up with?

By Wavelength

  • What is radio astronomy?

Astronomy & Society

  • Astrology vs Astronomy: What’s the difference?
  • How is the date of Easter determined?
  • How did early astronomers calculate accurate solar system positions?

The Kavli Foundation Q&As

  • A “Living Dead” Star Sheds Light on the Early Universe
  • A New Map of Dark Matter?
  • What’s Life Like at the Remotest Telescopes?
  • Do Globular Clusters Generate Black Holes?
  • How Did the First Quasars Form?
  • How Do Galaxies Die?
  • How are Gravitational Waves Detected?
  • How Did Nature’s Heaviest Elements Form?
  • How Do Planets Form?
  • How Will Gravitational Waves Reveal a Hidden Universe?
  • How Do Citizen Scientists Drive Discovery?
  • Pluto Revealed – The Historic Voyage of New Horizons
  • What Ignites Supernova Explosions?
  • Dwarf Galaxies and the Quest for Dark Matter
  • Insights Into Cosmic Inflation
  • What Has Planck Taught Us About the Early Universe?
  • Dark Matter at Long Last? Three New Experiments Ramp Up
  • Understanding the Fermi Bubbles
  • The Large Synoptic Survey Telescope
  • Microbes and the Search for Extraterrestrial Life

Hobby-Based Q&A

Delve into the hobby of astronomy: learn about different types of equipment and what they can do, and discover the limits (read: challenges) of observing the night sky with instruments and the unaided eye. The Q&As presented here cover a wide range of readers’ questions, and we’ve responded with detailed and well-researched answers. Search for a specific question or just browse through — our readers have come up with some interesting hypotheticals over the years!

If there’s a question that hasn’t been asked, ask it yourself by sending a note to [email protected]

General Observing

  • What’s my naked-eye magnitude limit?
  • Should I wear eyeglasses while observing?
  • What happens at star parties?
  • How do you pronounce “Vega” and “Canis Major”?
  • What was that flashing light in the sky?
  • What is the faintest object imaged by ground-based telescopes?

Observing the Sun

  • 4 FAQs about the next solar eclipse
  • How can you determine a sunspot’s size compared to that of Earth?
  • What is a sundog, and how did “sundogs” get their name?
  • When is the earliest sunrise of the year?
  • How many daylight hours do you get in a year?
  • Does the Sun always rise in the east?

Observing the Moon

  • What are the phases of the Moon?
  • Why does the Moon rise later every night?
  • How is the time of new (or full) Moon defined?
  • Is it possible to have no full Moon in February during a leap year?
  • When’s the next blue Moon?
  • Would a perfectly reflecting full Moon be just as bright as the Sun?
  • Could the lunar crescent be seen in a telescope at new Moon?
  • How does the Moon’s phase affect the skyglow of any given location?
  • Could I see astronauts on the Moon?

Observing Satellites

  • How can I spot satellite triads?

Observing the Planets

  • Is it possible to see the crescent of Venus?
  • Can Venus ever be far enough from the Sun to appear east of the meridian?
  • Will we ever see a mirror image of the conjunction of Venus and crescent Moon, as depicted on the Turkish flag?
  • Will Mercury and Venus ever transit the Sun simultaneously?
  • Why do photos of lunar or Martian craters sometimes appear inside-out?
  • Is it possible to detect Jupiter’s satellites with the unaided eye?
  • Do Saturn’s moons cast observable shadows?
  • What defines a planet’s north pole?

Observing Comets, Asteroids & Meteors

  • Does a comet’s tail tell us what direction it’s heading?
  • Will it ever be possible to observe Halley’s Comet around its entire orbit?
  • How can amateurs find asteroids?
  • What’s the phase of the Moon during next year’s Perseid meteor shower?
  • How well defined is a meteor shower’s radiant?

Observing Stars

  • Were stars artistically depicted with diffraction spikes before the invention of the Newtonian reflector?
  • If stars appear as points, why are some stars big and some small in different images?
  • Where can I find double star SAO numbers for my Go To telescope?
  • On what date were the two principal stars of the Alpha Centauri system last known to be closest to each other?


  • Should you set your digital camera to a low or high ISO value in twilight?
  • Can you get sharper images by stopping down your scope with a cardboard mask?
  • Why do people doing CCD imaging often stack five 1-minute exposures instead of taking just one 5-minute exposure?
  • How can an astrophoto shot through a refractor have diffraction spikes on bright stars?
  • Is obstruction of less consequence for photography than for visual observing?
  • What does “true color” mean in a deep-space photograph?

Astronomy Equipment


  • Focal ratio vs. aperture: which makes an object look brighter through a telescope?
  • Can a telescope increase an object’s surface brightness?
  • How far away are the stars I see through my telescope?
  • What’s the most distant object I can see with my telescope?
  • Is there a good test for optical quality?
  • How can I see more colors through my telescope?
  • How can I prevent my finder from dewing over?
  • How can I polar align in the daytime?
  • What should I do if my telescope mirror is dusty?
  • How will I know when my telescope mirrors need re-aluminizing?
  • Would a large concave mirror suffice for low-power views of extended deep-sky objects?
  • How can I get my German equatorial mount to hold its tilt?
  • Why do Schmidt-Cassegrain telescopes have focal ratios of f/10?
  • Can you adjust a spherical mirror to act like a parabolidal mirror by racking the focus farther out?
  • What does “lignes” mean for the aperture of an antique telescope?

Amateur Telescope-Making

  • Will I save money by making my own telescope?
  • Are machine-made telescope mirrors better than those made by hand?
  • What size first telescope mirror should I make?
  • Is software available to analyze optical designs of telescopes?

Eyepieces / Optics

  • How do I clean eyepiece lenses?
  • How can eyepieces offer a telescope’s widest true field?
  • What’s the difference between these two Plössl eyepieces?
  • Where did the 1 1/4-inch standard size for eyepiece barrels come from?
  • Why do the best roof-prism binoculars need a phase-correction coating?


  • What’s the difference between nebula filters and light-pollution filters?
  • Why do you need a hydrogen-alpha filter to see solar prominences?
  • Can an OIII nebula filter be called “oh-three”?


Questions on S&T Articles

  • Why are there two peaks in the light curve on page 97 of the October 2005 issue?
  • Why doesn’t S&T produce a star atlas with mirror-image charts?
  • Can you run programs from past issues of S&T, written in BASIC, on a Windows XP computer?
  • Why does S&T use light-years instead of parsecs for astronomical distances?
  • What is the unfamiliar star in Johnny Horne’s image of the Horsehead Nebula?
  • How can a telescope have an f/ratio of f/42 (re: January 2006 issue)?

Sky Atlas Questions

  • Why are the Large and Small Magellanic Clouds not listed among the Caldwell objects?
  • When will (or did) the galactic equator cross the ecliptic very close to the latter’s northern and southern extremes?

Math Questions

  • How many digits are satisfactory in the measurement of pi?
  • What does “error” mean?
  • Do error bars have to overlap the line of best fit?
  • How do you convert celestial coordinates for equinox 1950.0 to 2000.0?

Really, Really Miscellaneous Questions

  • Why aren’t Earth’s night skies more colorful?
  • How could an astronomer living on the far side of the Moon verify Earth existed?
  • Did an earthquake alter Earth’s rotation and tilt?
  • What is the most distant human-caused event that’s been easily verifiable with ordinary optics?
  • Why doesn’t a GPS receiver read longitude 0° 00′ 00″ while standing on the prime meridian at the Greenwich Observatory?
  • Can you use a replica of an 18th century New England sundial in Washington?
  • What was the cloud spotted near the western horizon August 31, 2004?

What is space made of? It’s complicated …

“Space is big. Really big. You just won’t believe how vastly, hugely mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.”

Douglas Adams was right. And not only is space big, we don’t know what it’s made of.

Astronomers have worked out that only about 5 per cent of our universe consists of baryons — the particles which make up atoms, which in turn make up molecules, which in turn make up everything we see, touch, smell, and taste.

About 20 per cent is dark matter — a mysterious substance that interacts with our universe only through its gravitational pull — and the rest, a whopping 75 per cent, is dark energy, a cosmic field that permeates everything.

It might sound the stuff of science fiction, but it is the best explanation of the large-scale features of our universe.

Dark energies

Baryons and dark matter tend to clump together due to their gravitational pull, while dark energy pushes everything further apart. And that’s causing our universe not only to expand, but to accelerate in that expansion.

We’ve estimated the rate of acceleration by using the Planck telescope to map the cosmic background radiation left over by the Big Bang. Final data, released by the Planck mission last month, reaffirm that dark matter and dark energy must exist, even if we don’t know what they are.

In a few hundreds of billions of years, everything but our nearest neighbouring galaxies will have moved out of reach: no matter how fast future humans might travel, we’ll never be able to reach anything else.

External Link: Hang on! It’s a long way to the next galaxy.

A recent study speculated that if an alien civilisation grew to the point where it needed whole galaxies as energy sources, it might have to leave its own galaxy and “mine” other galaxies for stars, reconfiguring the cosmos itself, before it all expands out of reach.

Farfetched? If you’re advanced enough to worry about the stars going out, perhaps it’s just contingency planning at its finest.

Aliens and dark energy aside, there sure is a lot of space — we know the universe is at least 30 billion light years across, and might even be infinite.

What is in this space?

Mostly, nothing.

But almost everything that is out there, is hydrogen.

Hydrogen: mostly hot air?

Hydrogen is the lightest element — it is simply a single electron and a single proton, orbiting each other.

Hydrogen can be found everywhere, from hot, dense stellar nurseries where new stars form, to the cold and tenuous voids between galaxies.

It’s the most abundant element in the universe, making up 75 per cent of all its atoms.

But most hydrogen atoms floating in space are so spread out, they’re essentially invisible to astronomers. So how can we tell if they’re there?

Well, it depends on what type of hydrogen it is: ionic, atomic or molecular.

Ionic hydrogen is formed when a nearby hot, bright star splits (or ionises) a hydrogen atom into protons and electrons.

Atomic hydrogen is created in parts of the universe that are cold enough to allow protons and electrons to recombine.

Molecular hydrogen (H2), which is the same form we find here on Earth, is formed in giant clouds where the hydrogen becomes dense enough that two pairs of atoms stick together.

This is really how astronomers see the periodic table according to astronomer and author Heidi Weissman Kneale (Supplied: Heidi Weissman Kneale (@heidikneale))

This is really how astronomers see the periodic table according to astronomer and author Heidi Weissman Kneale

Supplied: Heidi Weissman Kneale (@heidikneale)


We also sometimes find other molecules in these clouds ranging from simple carbon monoxide (CO) to more complicated like ethanol (C2H6O) — that’s right, astronomers are searching for beer in space.

Atomic and molecular hydrogen are relatively easy to find because they absorb and emit particular wavelengths of light, giving each a unique telltale signature that astronomers can measure.

Ionised hydrogen is almost totally invisible, except for one amazing feature: it makes things twinkle.

When you look up at the night sky, you might see stars, and also perhaps a few planets. The planets are distinctive because they don’t twinkle, while all the stars do. This is because the stars are so far away that all their light travels along a single, very thin beam toward us.

The thin beam is distorted as it travels through our constantly moving atmosphere, making the light look a little brighter or a little darker moment to moment. Planets are close enough to Earth that their beam of light is too large to be “scintillated” like stars.

Indigenous Australians have used the twinkling of stars to forecast the weather for tens of thousands of years.

The same thing happens with galaxies, which produce radio waves. These waves are scattered by the electrons of the ionised hydrogen in exactly the same way as our own atmosphere scatters light from stars.

Distant galaxies appear to twinkle, and that twinkling tells astronomers that space isn’t empty, but filled with incredibly diffuse ionised hydrogen.

Space is broken, I’m calling a quantum mechanic

What about the space between hydrogen atoms? What is a vacuum made of? Is there a smallest possible scale? Is space fundamentally smooth, with infinite resolution, or is it made up of some very, very, very, tiny pixels?

This is where things get really weird.

Top 5 promo in space story

On the very smallest scales, it appears there is a minimum “resolution” to the universe, called the “Planck length”, after the physicist Max Planck.

On these scales, the universe appears to be a strange quantum foam, with “virtual” particles popping in and out of existence, obeying the laws of quantum mechanics.

Despite how counterintuitive this sounds, we can actually measure the effects of quantum mechanics in the laboratory, for instance via the Casimir effect.

If you place two thin, flat plates just nanometres apart, in a vacuum, classical physics (and common sense) would tell you that the space between them is empty.

But the sea of virtual particles predicted by quantum physics is affected by the boundary of the plates: fewer virtual particles can be created in this small confined space than on the outside of the plates.

This causes the plates to get pushed together by the larger number of virtual particles bouncing off the outside. Even though, to all other measurements, both between and outside the plates, there is nothing there.

The Casimir effect: fewer virtual particles can exist inside the plates than outside, causing the plates to be squeezed together. (Wikimedia commons: Emok)

The Casimir effect: fewer virtual particles can exist inside the plates than outside, causing the plates to be squeezed together.

Wikimedia commons: Emok


This “vacuum energy” might actually be the key to understanding the dark energy of the universe on its largest scales.

Reconciling the vacuum energy with dark energy is a problem that scientists have been working on for decades, without much success.

String theory, which theorises that all matter and energy might be made up of tiny strings as small as the Planck length, holds hope for some physicists.

Cartoon explaining string theory. Sort of. (Supplied:

Cartoon explaining string theory. Sort of.



Others aren’t convinced, since the model doesn’t seem to predict anything that can actually be tested.

One thing scientists all agree on, is that empty space is surprisingly complicated.

Dr Natasha Hurley-Walker is an astrophysicist at the International Centre for Radio Astronomy Research at Curtin University. She is also one of the ABC’s Top 5 scientists for 2018.

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SkyView® Lite brings stargazing to everyone! Simply point your iPhone, iPad, or iPod at the sky to identify stars, constellations, satellites, and more!
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If you like our lite version of SkyView then you’ll love our full version! It includes: a convenient Apple Watch app, a Today Widget displaying tonight’s brightest objects, ALL in-app purchases offered in this version, thousands more objects to discover, and more!
App Store Best of 2012
App Store Rewind 2011 — Best Education App
“If you’ve ever wanted to know what you’re looking at in the night sky, this app is the perfect stargazer’s companion.”
“If you’ve ever been looking for a stargazing app for your iPhone, then this definitely the one to get.”
– AppAdvice
“SkyView is an Augmented Reality app that lets you see just what delights the sky has to offer.”
– 148Apps Editor’s Choice
You don’t need to be an astronomer to find stars or constellations in the sky, just open SkyView® Lite and let it guide you to their location and identify them. SkyView® Lite is a beautiful and intuitive stargazing app that uses your camera to precisely spot and identify celestial objects in sky, day or night. Find your favorite constellations as they fade in and out while you scan across the sky, locate the Moon, discover distant galaxies, and witness satellite fly-bys.
• Simple: Point your device at the sky to identify galaxies, stars, constellations and satellites (including the ISS and Hubble) passing overhead at your location.
• Sightings: set reminders for celestial events and plan an evening stargazing & spotting satellites.
• Augmented Reality (AR): Use your camera to spot objects in the sky, day or night.
• Sky Paths: Follow the daily sky tracks for the Sun and Moon to see their exact locations in the sky on any date & time.
• Time Travel: Jump to the future or the past and see the sky on different dates and times.
• Social: Capture and share beautiful images with friends and family on social networks.
• Mobile: WiFi is NOT required (does not require a data signal or GPS to function). Take it camping, boating, or even flying!
• Supports Space Navigator™ binoculars, spotting scope, and telescopes.
What a fun way to teach yourself, your children, your students, or your friends about our wonderful universe!

Sky Map

Sky Map is a hand-held planetarium for your Android device. Use it to identify stars, planets, nebulae and more.
Originally developed as Google Sky Map, it has now been donated and open sourced.
The Map doesn’t move/points in the wrong place
Make sure you haven’t switched into manual mode. Does your phone have a compass? If not, Sky Map cannot tell your orientation. Look it up here:
Try calibrating your compass by moving it in a figure of 8 motion or as described here

Are there any magnets or metal nearby that might interfere with the compass? Try switching off “magnetic correction” (in settings) and see if that is more accurate.
Why is autolocation not supported for my phone?
In Android 6 the way permissions work has changed. You need to enable the location permission setting for Sky Map as described here:

The Map is jittery
Try adjusting the sensor speed and damping (in settings). We have a better solution coming soon!
Do I need an internet connection?
No, but some functions (like entering your location manually) won’t work without one. You’ll have to use the GPS or enter a latitude and longitude instead.
Can I help test the latest features?
Sure! Join our beta testing program and get the latest version.

Find us elsewhere:
* (github – source code)
* (Google Plus)

People have been staring at the starry night sky ever since the world began, wondering what it all means. While previously, you could only analyze constellations with charts, maps, and telescopes — or pay a visit to the nearest planetarium — today you can use mobile apps to uncover a vast amount of information about what’s happening overhead at any given time. Backyard stargazers use apps to discover a wealth of information on the location and identity of planets, stars, and galaxies — no telescope needed.

The best astronomy apps use the gyroscope and compass in your smartphone or tablet, along with date, time, and location services, to determine your whereabouts. While an internet connection is helpful, it’s not always strictly necessary for every app. If you’re in the wilderness, far from a Wi-Fi or cell connection, you can still benefit from astronomy apps. Some also use augmented reality through the device’s camera to show you exactly where stars are positioned. Most apps are extremely easy to use and targeted to beginners and enthusiasts — just point your device’s camera toward the heavens and find the stars and constellations.

Because the Earth rotates every 24 hours and the planets orbit around the sun every 365.25 days, stars land in predestined positions so that the same ones appear at the same date and time on an annual basis. Your location dictates which constellations are visible. Many sky-charting apps manage celestial objects with categories or lists. The Messier List, for example — researched and published by Charles Messier in 1781 — includes 110 deep-sky objects viewable from the Northern Hemisphere, and is a popular feature for such apps.

Inspired to see what’s overhead? Here are a few of the many cross-platform iOS and Android apps we discovered.

Star Rover

Star Rover acts as your device’s built-in planetarium. Just hold up your phone, use a pinch-to-zoom gesture, and have the app pinpoint whatever is up there. After determining your position, the app locates stars, the moon, planets, and constellations. The sky map updates dynamically as you move your phone around the block, neighborhood, or region to see twinkling stars, nebulae, meteors, and sunset glow. Star Rover, which costs $2, catalogs over 120,000 stars, all 88 constellations, planets and their moons, moon phases, and real images of Messier objects. Detailed information covers sky objects, equatorial and azimuthal grids, the Milky Way Galaxy, sunrise and sunset, eclipse simulation, and more.

iOS Android


With SkySafari, all you have to do is hold your device up to the sky and let the app quickly assemble planets, constellations, satellites, stars, and deep sky objects. Featuring interactive information accompanied by rich graphics, the app lets you view 120,000 stars; more than 200 star clusters, nebulae, and galaxies; all major planets and moons; and a variety of asteroids, comets, and satellites, including the International Space Station (ISS). You can use the app to animate a variety of celestial events such as meteor showers, comet approaches, transits, and conjunctions. SkySafari lets you simulate the night sky from anywhere on Earth and move backward and forward in time. Rich graphics show you detailed views of galaxies and constellations. The Tonight’s Best feature highlights the most interesting current events.

iOS Android

SkyView Lite

You don’t need a telescope to see the stars and constellations as long as you have Sky View Lite, an intuitive free mobile app that helps you find and identify sky objects like stars, planets, and satellite flybys from the likes of the International Space Station and Hubble Space Telescope any time of the day or night. An augmented reality feature lets you use your camera to spot objects in the sky at any time. The app also features sky paths for tracking objects, and a social feature that lets you share discoveries with friends and family. There’s no need for Wi-Fi, cell, or GPS — the app functions fine without them.

iOS Android

Cosmic Watch 2

This award-winning augmented reality-assisted app lets you explore outer space by simply pointing your mobile device skyward. Play astronaut for a flight through the solar system, learn about the stars and constellations in the sky right above you,or time travel to past or future skies. Cosmic Watch 2, which costs $5, calculates singular astronomical events so you never miss out on the next big cosmic thing. The app features layered presentations, a 3D celestial sphere of the whole sky, a planetarium with star maps, an astronomical events calculator, a 3D astronomical clock, and a world clock. It also offers separate sky, earth, and solar system views, a geocentric and heliocentric solar system view, and much more.

iOS Android

Solar Walk 2

Solar Walk is a comprehensive encyclopedia of the solar system anchored by a 3D model. Use the app to explore space, spacecraft, and planets via an interactive planetarium augmented by panoramic photos. You can watch satellites, comets, asteroids, and dwarf planets, explore space missions and spacecraft, and check out the celestial event calendar. All celestial bodies are represented in their correct real-time positions. You can also view realistic 3D models of spaceships, satellites, and interplanetary stations and track their flight path trajectory, watch gravitational moves, and view photos shot during the mission. The astronomy calendar includes various celestial events like the solar eclipse, lunar eclipse, and moon phases, and documents historical space travel. A social feature lets you share discoveries with friends and family on Facebook. An ad-supported Premium Access version costs $3.

iOS Android

Stellarium Mobile Sky Map

If you’re curious about stars, constellations, planets, comets, satellites such as the International Space Station, and deep sky objects, Stellarium is an app that gives you the lowdown without getting in your way. Stellarium Mobile Sky Map provides a simple, minimalist interface that’s great for beginners and kids, along with a 3D rendering of the major solar system planets and their satellites. Find out all you need to know about the sky above you with the app’s catalog of more than 600,000 stars, displayed as an adjustable sky map. The app lets you discover how others interpret the stars, and see Milky Way and deep sky object images, simulations of star extinction, atmosphere refraction, and more.

iOS Android

Star Walk 2

Star Walk 2 assists you in exploring the sky. Satisfy your curiosity by identifying stars, constellations, planets, satellites, asteroids, comets, spacecraft, nebulae, the ISS, Hubble Space Telescope, and other celestial bodies in real time with your smart device. In addition to the stars, you can have a look at meteor showers, equinoxes, conjunctions, even full and new moons. The free, ad-supported app displays a real-time map of the sky on your screen in whatever direction you point your device. Pan to navigate your view on screen by swiping in any direction, pinch to zoom out, or stretch to zoom in. A clock icon at the upper-right corner of the screen facilitates date selection forward or backward to watch the night sky stars and planets in accelerated motion. You can also view night sky objects in augmented reality. Tap on the image of the camera on the screen and the app will activate your device’s camera so you can see charted objects superimposed on the live sky. A What’s New section details the most interesting astronomical events.

iOS Android

Star Tracker

This favorite among stargazers is a simple app for viewing stars, constellations, and deep sky objects. The ad-supported, free app (called Lite in iOS)shows the sun, moon, and planets in the solar system, 88 constellations and more than 8,000 stars, and assorted famous deep sky objects with the location set either automatically via GPS or manually. You can hide all menus and enter AR track mode when you point your device to the sky. The $3, ad-free version lets you search for celestial objects and elements. It also has a 3D compass in AR mode and a night mode switch, and lets you explore beyond the boundaries of time.

iOS Android

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  • Ten years in space: Remembering a decade of achievements in the final frontier
  • See the giant galaxy named after pioneering dark matter researcher Vera Rubin

SkySafari – Astronomy App

SkySafari is a powerful planetarium that fits in your pocket, puts the universe at your fingertips, and is incredibly easy to use!
Simply hold your device to the sky and quickly locate planets, constellations, satellites, and millions of stars and deep sky objects. Packed with interactive information and rich graphics, discover why SkySafari is your perfect stargazing companion under the night sky.
Notable Features:
• Ever wanted to know what the sky looked like in 500 B.C.? What about in 2190? With SkySafari, you can simulate the night sky from anywhere on Earth many years in the past or future! Animate meteor showers, comet approaches, transits, conjunctions, and other celestial events.
• Rich graphics unlike you’ve ever seen before! See galaxies, constellations, and more in stunning and vivid detail. Plus, optional constellation illustrations that will blow your mind.
• Just browsing the sky for something to look for? Check out the Tonight’s Best feature, which tells you which objects you’ll get the best view of tonight.
• Raise your device to the sky and SkySafari will find stars, constellations, planets, and more! The star chart updates automatically with your real time movements for the ultimate stargazing experience.
• Night Vision – Preserve your eyesight after dark.
• Locate the Sun, Moon, or Mars from our extensive database and track the arrow to be directed to their exact locations in the sky in front of you. See spectacular views of Venus, Jupiter, Saturn, and other planets!
• Learn about the history, mythology, and science of the heavens! Browse from hundreds of object descriptions, astronomical photographs, and NASA spacecraft images. Plus, stay up-to-date with SkyWeek for information about all major sky events every day – miss nothing!
• Watch animated meteor showers with complete viewing information & spectacular graphics.
• View 120,000 stars; over 200 star clusters, nebulae, and galaxies; all major planets and moons; and dozens of asteroids, comets, and satellites, including the International Space Station (ISS).
• Orbit Mode – Leave the Earth’s surface behind, and fly like a NASA space probe through the solar system (requires in-app purchase).
• Much more!
New in Version 6:
1) Complete support for Android 8. We’ve got you covered and release regular updates.
2) Clouds and astronomy, two words that rarely go together. SkySafari 6 will now (optionally) back up all your settings files and make it easily accessible on multiple devices as well as from our new web interface,
3) Redesigned toolbar, now with the ability to hide. Invisibility powers, activate!
4) Configurable font sizes – having trouble telling if that number is a 5 or a 6? Just make it bigger!
5) Better control of magnitude limits – for example, you can select to not see stars on the app that you can’t see with your naked eye!
6) Improved the databases!
7) Updated information for comets and asteroids!
8) Now the moon looks better when you zoom out! 🌚
Optional Feature:
Cosmos Collection: In-app purchase allows you to travel to other planets and stars, visualize the 3D location of deepsky objects in our galaxy, and listen to hours of audio guided tours of the heavens.
The Cosmos Collection includes:
Orbit Mode
Lift off from the Earth and travel to the planets, moons and stars.
Guided Audio Tours
Listen to more than four hours of audio narration to learn the history, mythology, and science of the heavens.
Galaxy View
Visualize the 3-D location of stars and deep sky objects in the Milky Way, our home galaxy.
“Yoor-ah-nus”, not “Your-anus”? The pronunciation guide in SkySafari will help you learn how to correctly pronounce the names of hundreds of celestial objects from different categories such as stars, constellations and planets.
For more deluxe features and telescope control, check out SkySafari 6 Plus and SkySafari 6 Pro!

Love Stargazing? Here Are Our Top 6 Astronomy Apps!

Stargazing just got real! What once used to be a backyard pastime has been taken to the next level with the emergence of astronomy apps. Now users can experience the beauty of space like never before. Here are our top 6 picks for astronomy apps (that are free)!

1. SkyView Lite

SkyView allows users to point their device to the sky and instantly identify stars, constellations, and satellites. The app provides endless information on the world above and even provides notifications for upcoming stargazing events.

2. Star Walk 2 Ads+

The app Star Walk does not only have a beautiful interface, but is extremely user friendly. The apps effortless design allows users to explore stars, comets, and constellations all by pointing their device at the sky. This version of the app includes ads, but for $2.99 you can get an ad-free experience.

3. Star Chart

The app Star Chart provides user a view into the the visible universe at the tip of their fingers. With information like distance,brightness and object references you’ll be a mini astronomer in no time!

4. Night Sky Lite

Night Sky allows users to quickly identify stars, constellations, satellites and planets as well as weather conditions for the coming night. On top of this information, Night Sky has a community that provides suggestions for the best stargazing locations around the world!

5. SkySafari

The app SkySafari features all the basics for the perfect stargazing experience. The app allows the user to simply point their device at the sky and even includes helpful features like voice control, which allows users to easily search for items or select items to be viewed closer.

6. NASA app

Although this app is not built for stargazing, the in-depth information from NASA will have users looking to the skies in awe of the wonders of space! This app features the latest images, videos, news and mission information straight from the experts in the field.

Have an astronomy app you want to recommend? Let us know in the comment section!

5 Best Apps for Astrophotography

Download these top 5 best apps and turn your smartphone into an astrophotography tool!

A reliable camera and processing software are two essential items in astrophotography, but now your smartphone can be a part of your success. We recommend these best apps for night sky photography to optimize and enhance your experience and skill as an astronomer.

Some are free, some are not, but they’re all worth a look.

Celestron’s SkyPortal – Android & iOS

You may have not heard of this app until now because it is often overshadowed by the apps Sky Map or SkyView for Android and iOS, respectively. Celestron’s SkyPortal app is similarly free, but it is built by astronomers, for astronomers.

SkyPortal also comes with a database of celestial objects and constellations to look for with extensive text and audio details for many of them. While staring up at the star cluster Pleiades, you can get some insight into what it is and the history behind it all for free.

Another bonus from this app is that it’s exclusively for aspiring astronomers who already have Celestron telescope products. With this app, you are able to control WiFi compatible Celestron devices and even align your telescope using SkyPortal!

SkySafari – Android & iOS

SkySafari is essentially quite similar to SkyPortal in both interface and functionality. There’s a free version available for everyone, and it also has the option to upgrade with either $4, $15, or $40. Each upgrade expands the object’s database and features in the app. Either one of these first two apps are great, but if you’re really looking to ramp up your universal sight-seeing, this is the best astrophotography app for Android.

Another huge aspect of this, similar to SkyPortal, is that it can control WiFi compatible devices from a variety of brands. With SkySafari you are not limited to Celestron products only–no matter how great Celestron is (and they are). This is the app to download for serious astronomers.

Photo Pills – Android & iOS

This is a game-changer in DSLR astrophotography–and photography as a whole. We say DSLR because most features included in this app are designed for customizing your DSLR camera settings. These concepts can be applied to astronomy cameras as well, and modern smartphone cameras with professional customization, but it’s hard to replace a good ‘ole DSLR.

Boasting an exceptional feature list, PhotoPills takes much of the planning and busy-work out of your photoshoots. Planning for Milky Way shots? You’re covered. Need quick calculations for FOV and exposure settings? Done! We at OPT can’t recommend this app any more highly (within reason) than we already do.

PhotoPills does come with a price tag of $10 but considering the convenience and scope of functionality, we find it’s worth a lot more.

HD Camera Pro – Android Only

If you don’t have a DSLR, mirrorless, or astronomy camera, and instead use your phone for everything, then this and the next suggestion should be of interest to you.

HD Camero Pro is the best Android camera app that gives heavy customization to your phone’s camera settings. Exposure, ISO, and filters can all be modified as well as its HD videos. If you’re not interested in buying yourself a DSLR, this could be perfect for you.

ProCamera – iOS Only

This is essentially the same thing as the Android version above. ProCamera helps you modify your smartphone camera settings to a more professional level. Also included, is photo editing software to edit images you’ve just taken on-the-go. Again, if you’re not interested in getting yourself a DSLR, these camera apps are the way to go.

With any of these apps ready to go on your smartphone, you’ll be equipped to image the night sky or simply stargaze whenever the weather allows it.

Not sure where to look first? Check this out for some easy-to-find beauties in the sky!

As always, stay safe and keep looking up!

Star Walk 2 Free – Sky Map, Stars & Constellations

Star Walk 2 Free – Identify Stars in the Night Sky is a great astronomy guide to explore the night sky day and night, identify stars, constellations, planets, satellites, asteroids, comets, ISS, Hubble Space Telescope and other celestial bodies in real time in the sky above you. All you need to do is to point your device to the sky.
Explore the deep sky with one of the best astronomical applications.
Objects and astronomical events to learn in this stargazing app:
– Stars and constellations, their position in the night sky
– Solar system bodies (solar system planets, the Sun, the Moon, dwarf planets, asteroids, comets)
– Deep Space objects (nebulae, galaxies, star clusters)
– Satellites overhead
– Meteor showers, equinoxes, conjunctions, full/new Moon and etc.
Star Walk 2 contains in-app purchases.
Star Walk 2 Free – Identify Stars in the Night Sky is a perfect planets, stars and constellations finder which can be used by both adults and children, space amateurs and serious stargazers to learn astronomy by themselves. It is also a great educational tool for teachers to use during their astronomy classes.
Star Walk 2 Free in travel & tourism industry:
‘Rapa Nui Stargazing’ on Easter Island uses the app for sky observations during its astronomical tours.
‘Nakai Resorts Group’ in the Maldives uses the app during astronomy meetings for its guests.
This free version contains ads. You can remove ads through In-App purchases.
Main features of our astronomy app:
★ Stars and planets finder shows the real-time map of the sky on your screen in whatever direction you are pointing the device.* To navigate, you pan your view on screen by swiping in any direction, zoom out by pinching the screen, or zoom in by stretching it.
★ Learn a lot about the solar system, constellations, stars, comets, asteroids, spacecraft, nebulas, identify their position on the map of the sky in real time. Find any celestial body following a special pointer on the map of the stars and planets.
★ Touching a clock-face icon at the upper-right corner of the screen allows you select any date and time and lets you go forward or backward in time and watch the night sky map of stars and planets in fast motion. Find out star position of different time periods.
★ Enjoy AR stargazing. View stars, constellations, planets, satellites overhead and other night sky objects in augmented reality. Tap on the image of the camera on the screen and the astronomy app will activate your device’s camera so you can see charted objects appear superimposed on live sky objects.
★ Except for map of the sky with stars and constellations, find the deep-sky objects, satellites in space live, meteor showers. The night-mode will make your sky observation at night time more comfortable. Stars and constellations are closer than you think.
★ With our star chart app you will get a deeper understanding of the constellation`s scale and place in the night sky map. Enjoy observing wonderful 3D models of constellations, turn them upside down, read their stories and other astronomy facts.
★Be aware of the latest news from the world of outer space and astronomy. The “What’s new” section of our stargazing astronomy app will tell you about the most outstanding astronomical events in time.
*The Star Spotter feature won’t work for the devices that are not equipped with the gyroscope and compass.
Star Walk 2 Free – Identify Stars in the Night Sky is an impressively good looking astronomy app for stargazing at any time and place. It is the all-new version of the previous Star Walk. This new version has a re-designed interface in conjunction with advanced features.
If you’ve ever said to yourself “I’d like to learn the constellations” or wondered “Is that a star or a planet in the night sky?”, Star Walk 2 Free is the astronomy app you’ve been looking for. Try one of the best astronomy applications.

Love astronomy? Get your smartphone in on your love for the stars. While we used to turn to astronomy books and home telescopes to observe constellations and planetary bodies, now we have apps for that, scratch that, we have 10 apps for your iOS or Android device to help find the locations of stars, planets, satellites and space stations.

Many of these apps use augmented reality combined the device’s camera to show you exactly where the stars are. You can point your device’s camera towards the sky and find the position of stars and constellations.

You can then use these apps to find out more educational information about a celestial body, or to plan ahead for your stargazing activities.

Recommended Reading: Falling Stars & Meteors Wallpapers

1. Star Chart

Apart from the augmented reality apps like Star Chart affords users, this app goes the extra mile when it comes to time travel, about 10,000 years forward or backward in time. You can also change your location to view the night sky from other points on Earth, and in-app purchases unlock enhanced star catalogues, meteor showers, comets etc.

Download app for: iOS | Android

2. NASA App

Love to catch up on what NASA the space agency is working on? This NASA app keeps you in the loop about the latest NASA missions plus images (updated daily), news, features, tweets, satellite trackers and even live stream from NASA TV. It also has launch information, a countdown clock and it tracks the ISS sighting opportunities.

Download app for: iOS | Android

3. Night Sky

Despite the information you can get from these stargazing apps, at the end of the night, all we want is to gaze at stars. This app comes with a community that suggests great stargazing locations across the world. On top of that, it also checks weather conditions for the coming night so you know if it is a night worth staying up for stargazing.

Download app for: iOS

4. SkyView Free

SkyView uses the back camera to give you information like the paths of objects in the sky and names of the bright lights you see. You can also search for and locate specific stars or space stations. Like something you see and want to share it with the world? Sharing is enabled on Twitter, Facebook and Instagram.

Download app for: iOS | Android

5. GoSkyWatch Planetarium

This app is available exclusively for the iPad. With its big screen, and 180 degrees view, it shows you information about any star or planet that you can view with the naked eye. Planets are shown in relative brightness. Touch any celestial object for a pop up that shows you the information about the object.

Download app for: iOS

6. ISS Detector

Did you know that you can see the International Space Station (ISS) with the naked eye? This ISS Detector app can notify you with an alarm 5 minutes ahead of time before the ISS flies by. With in-app purchase, it also lets you track the Tiangong space station, the Hubble space telescope, satellites and comets too.

Download app for: iOS | Android

7. Sky Map

With Google Sky Map uses compass data and GPS to accurately identify the celestial object you are pointing your phone at. It can direct you to the section of the sky you should be observing, to find the object of your desire or you can ‘time travel’ and find out where the object will be at a different (later) hour of the night.

Download app for: Android

8. SkEye Astronomy

With this app installed, you can strap your phone onto the OTA of your telescope to guide you on where to look. The database has 180 bright objects, Messier objects, planets in our solar systems and you can use the Time Machine object to jump ahead and plan your nightly stargazing events.

Download app for: Android

9. Star & Planet Finder

Pick a star, planet or satellite from the list and it will show you where it is by using your device’s back camera and pointing you to the correct direction. The free option comes with only a few planets, but if you like the app, you can unlock other stars and satellites with in-app purchases.

Download app for: iOS

10. Satellite Augmented Reality

If for some reason you would like to observe and track satellites instead of natural objects in the sky, this app can help you track the path and location of satellites orbiting our earth. You can search through a database to look for the one you want, and then point your device towards the sky and it will show you where it is.

Download app for: iOS | Android

Explore the night sky with the best astronomy apps

Humanity has been gazing at the stars since the dawn of civilization, finding points of navigation and dreaming of what lay beyond. Previous generations could only learn about the specifics of the skies through star maps, books, and planetariums. Today, everyone is walking around with the ability to study the cosmos in their pockets thanks to astronomy apps.

Modern astronomy apps use all the technology packed in your mobile devices — a compass, GPS, gyroscope, time, and dates — to give stunningly accurate maps of the stars. Many don’t even require you to have a data signal to use, allowing you to see the majesty of the stars even while hiking in rural areas.

Best astronomy apps

Night Sky (Free, premium upgrades)


In the world of astronomy apps, one name reigns supreme: Nightsky. This freemium app offers a jaw-dropping amount of features without ever asking for a dime, but if you’re willing to pay the options are seemingly endless. Free users get one of the largest collection of star maps on earth, featuring millions of stars. An augmented reality feature uses your camera to map the stars in the sky above exactly as you see it. Whether you want to see stylized constellations or traditional outlines, Nightsky has you covered. Users get access to powerful filters, from a light pollution indicator to x-rays to let you see beyond the standard visual spectrums. There are quizzes to test your knowledge and educational functions that teach you about the internal structures of planets throughout the solar system. Premium users also get the ability to map the closest Aurora to your location. You can even add the time you spend stargazing to your mindfulness minutes in your Apple Health app. The only downside of the app is how overwhelming its sheer number of options can be for new users.

Skyview ($1.99)

Overwhelmed by Nightsky? Try Skyview. This simple point and view astronomy app make it easy to quickly identify galaxies, stars, constellations, and planets. You can even track satellites that might be above you at any moment, including the international space station. Scheduling features make sure you never miss a major celestial event that comes in handy for those one-in-a-lifetime planetary moments. Skyview has a wonderfully simple augmented reality feature that takes images from your camera and overlays constellations directly where they naturally occur in the sky. There’s even a time jump option, letting you see what the stars would look like at your location during different time periods. Skyview offers a ton of options for one low cost.


SkySafari ($1.99)

While many apps have features that empower you to learn, SkySafari actually teaches you. Included in the cost of the app are a series of audio tours through the stars and planets. A recent update has expanded the educational options even further with histories and models of the entire Apollo Lunar Missions, including a guided tour of the Apollo 11 mission. Like most other astronomy apps it also features augmented reality options and a pocket planetarium, but the educational features are truly the highlight of SkySafari. For young astronomers looking to learn more about the sky, SkySafari is worth signing up for.


Cosmic Watch ($4.99)

Apple The vast majority of astronomy apps aim to use augmented reality to show you the sky above you. Cosmic Watch 2 would rather show you what’s above in detail, via a high-definition 3D planetarium and clock. Blending time measurement with astronomy, Cosmic Watch allows you to view the stars from a historical perspective. Featuring star maps, a planetarium, and an astronomical event calculator, Cosmic Watch provides a view of the sky unlike any other app on the market. Its interactive maps feature variable textures for night and day along with both geocentric and heliocentric views of the solar system. And just in case you decide you really need to see the sky via augmented reality, Cosmic Watch 2 also throws in an AR view to boot. Its $4.99 price tag may be the highest on this list, but it’s easily one of the best astronomy apps in the cosmos.

Star Rover ($1.99)

Apple Star Rover is designed as a mobile virtual planetarium, showing a stylized map of the stars anywhere in the world. In its standard mode users simply point their device to the location in the sky they want to see the stars. Star Rover brings up a beautiful virtual map of the sky, displaying the constellations, planets, stars, and moon exactly where they appear in real life. Users can also manually select their location, allowing you to see what the stars look like at any moment, anywhere in the world. The app even includes details about specific constellations and planetary bodies, empowering you to easily learn more about the stars you spot. Never let a cloudy night keep you from seeing the stars above thanks to this virtual planetarium experience. With 120,000 stars, Star Rover isn’t the most comprehensive experience, but it’s a visual treat for kids and adults alike.