Any space-loving backyard astronomer should have a trusted sky map to reference when stargazing or peering through the viewfinder of their telescope, and app developers have stepped up to offer a wide array of options for Android and iOS users. Although the earliest star map, a carving of the constellation Orion on a mammoth tusk, is over 32,000 years old, most current maps are thankfully digital.
From planetarium simulators to lists of object coordinates, there are numerous, varied astronomy-themed apps available. Here are some of the most popular ones this year:
Star Walk 2
Star Walk 2 is a stargazing app with a beautiful, crisp UI. It offers a variety of camera modes: free roam, scroll/manual, and augmented reality. You can travel in time to see skies from the past and future, and the app also boasts an interesting "What's New" feed of the latest astronomy news. Unfortunately, the free app is pretty basic, and the amount of ads are unduly disruptive. Pretty much every tap generates full screen ads, which detracts heavily from the gorgeous aesthetic and smooth interface. The developer offers an ad-free version for $2.99 with expansions that add deep sky objects, satellites, etc. for $0.99 each. Overall, Star Walk 2 is an attractive, intuitive app, but the unpaid version is quite limited, and other apps offer the same features for free.
Interestingly, the developers also offer a kid-friendly version of Star Walk 2 with appealing graphics and an age-appropriate design. The level of detail give this app a great deal of versatility; both parents and educators would find it a useful tool in educating children about space.
Quick summary: This app has great aesthetics but is hampered by aggressive, frequent ads and an overly reduced free version.
SkyView
SkyView Free is another sleek, modern stargazing app, and it was a Google Play Store Editors' Choice in 2017. Quick-loading and with a snappy interface, SkyView Free offers more features in the unpaid version than most of its competitors. You can tap on sky objects to get detailed descriptions, follow the projected path of an object in the sky, and toggle between right ascension/declination and altitude/azimuth coordinates. This app also has a handy red-tinged night mode for use outdoors and even atmospheric, calm music that serves as a perfectly tranquil backdrop to the constellations. Additionally, you can customize the size of the stars and planets in the sky, which makes the app more accessible for users with low vision. Finally, SkyView is the exclusive partner with Space Navigator telescopes, and this enables the user to more accurately orient their equipment and locate targets in the sky.
Quick Summary: With a whole host of useful free features, minimally invasive ads, and a beautiful design, this app is one of the best currently available.
Star Chart
Compared to the other apps, Star Chart struggles to stand out, especially considering that its best features are locked behind a paywall. Comets, meteor showers, satellites, and the extended Solar System are all available but for $3.99 each. That said, Star Chart does have some unique characteristics. The 3D Explore mode offers an interesting new way to observe the night sky, and allows the user to filter by object type (Solar System, stars, constellations, and Messier objects). Tapping on a target triggers a pop-up with more information, including the altitude and azimuth updated live. Despite the images being absolutely breathtaking, some of the icons are a bit too small and troublesome to consistently access, and the design can be rather cluttered when zoomed out in certain modes. Overall, Star Chart needs to offer a bit more, especially given its paid version is the most expensive on this list with a full cost of approximately $16.00.
Quick Summary: Despite the free version being a bit derivative and the paid version being quite expensive, Star Chart still has a few worthwhile perks.
Star Rover
Star Rover offers many of the same features as its competitors: augmented reality mode, object information, and the ability to change the observation time, but it falls behind in terms of usability and aesthetics. With a sluggish UI and only quite basic features, Star Rover is outclassed by other apps that run more quickly and look more modern. The font it utilizes is often a bit blurry and hard to read, which leaves the app looking dated. The free version also has ads, but thankfully they are infrequent and not terribly intrusive.
Quick Summary: Star Rover is a generic stargazing app that struggles to distinguish itself from its competitors.
SkyWiki
Although not exactly a planetarium simulator or VR stargazing app, SkyWiki has one of the best interfaces on this list. Easy to use, minimalist, and quite stunning, Sky Wiki also has numerous unique features. The Periscope page gives detailed information about Solar System objects in the sky as well as any relevant astronomical events. The Calendar page gives more information about those events in addition to records of both past and future events. However, some of the event details border on overly technical and often have jargon that beginning astronomers or just interested users may not know. In contrast, the Images page displays the Astronomy Picture of the Day, NASA image of the day, Lunar image of the day, and Hubble picture of the week. Together with informative captions, these beautiful images are an inspirational and accessible way to encourage users' passion for space. Unfortunately, the Skymap feature is only a 2D, static star map more akin to a planisphere, especially compared to the interactive, enhanced reality modes that other apps offer. Thankfully, the developer, Bluestreak Labs, has stated that a planetarium mode is in the works. Once that is released, this app will be one of the best currently available.
Quick Summary: Although lacking a planetarium mode, SkyWiki's unique, robust features and beautiful design make it a must-download app for astronomy enthusiasts.
Starlight - Explore the Stars
While it lacks most of the features and customization options of its competitors, Starlight excels at what it aims to do. There are no detailed settings, no options, and no additional object information; the app is simply the night sky with the more prominent constellations, stars, and planets labeled. The free version does have ads though, but they can be removed by purchasing the app for $1.99 (Android only). Due to the minimalism and pared-down approach, this would be a useful app for introducing younger users to the night sky. Apart from that, however, Starlight lacks true appeal due to the complete paucity of features.
Quick Summary: Despite some appealing design elements, Starlight does not offer much other than a very basic view of the night sky.
StarTracker - Mobile Sky Map
Compared to the previous apps, StarTracker follows a similar pattern; it offers an interactive view of the night sky with constellation, star, and planet names. However, the animations for the stars and constellations often obscure object names and are quite distracting. The free app also lacks a lot of features that are included in the free versions of other apps like being able to move through time or have detailed information on a particular target. Despite the interface being garish and cluttered at times, StarTracker does offer something that most of the other apps do not: VR support. While pretty similar to the standard app, the VR version gives an immersive experience that parallels a planetarium show better than any other app on this list.
Quick Summary: A clumsy interface and lack of features inhibit an otherwise well-done app that also boasts a version for VR.
SkEye
While it resembles a planetarium or stargazing app, SkEye truly excels as a tool for backyard or observational astronomers. While its interface is less stylized and sleek compared to the previous apps, it makes up for it in detail. The sky view displays the right ascension, declination, altitude, and azimuth coordinates, hour angle, phone battery, as well as the object name, type, magnitude, and apparent size. It is also one of the few apps to include both Messier and NGC deep sky objects. All of these features are part of the free version, though there is a paid pro-version that adds comets, complete NGC and IC catalogs, satellites, and rendering for all stars up to 10th magnitude. In sum, SkEye functions best as a tool for astronomy enthusiasts instead of an educational or outreach app.
Quick Summary: SkEye is a useful accompaniment for observing with a telescope, but not ideal for an introduction to the night sky.
There are numerous other free astronomy-themed apps with interesting features like NASA's official app, which offers a host of ringtones made from launch sounds or planetary emissions, or Dark Sky Map, which overlays light pollution data onto Google Maps in order to guide users to ideal locations for viewing the night sky. From children's apps that teach the names of the planets to detailed observational tools that even professional astronomers would find useful, star maps have clearly evolved beyond ancient carvings on a mammoth tusk.
