Star Walk 2 ($2.99) is a reboot of the Star Walk app, which was our first Editors' Choice planetarium-style astronomy iPad app. Like the original, Star Walk 2 is visually stunning. Although it has added features, parts of the content—including some items that were included with the original Star Walk—is only available through an in-app purchase, and Star Walk 2 no longer stands out among similarly priced apps.
In addition to Star Walk 2, Vito Technology also makes Solar Walk 2 and Dino Walk . Star Walk 2 can be used on an iPhone, an Apple Watch, an iPad, or an iPod touch. I tested the app on an iPad Air 2 running iOS 9.2.
Design and Features
Like other so-called planetarium apps, Star Walk 2 shows a starry sky on your iPad's screen in whatever direction you are pointing the device. This is true for day or night; during the day, you can see the Sun and the stars and planets portrayed in a twilight-blue sky. At night, the stars are visible against a black background. 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.
A clock-face icon is at the upper-right corner of the screen. Touching it reveals a digital clock, which displays the current time by default. Tapping on the year, month, date, hour, or minute, and then pushing a slider that runs along the screen's right-hand edge lets you go forward (by swiping upward on the slider) or backward (by swiping downward) in time and watch the heavens wheel in fast motion. A button to the left of the clock brings you back to the current time.
At the screen's lower right is a button that takes you to a menu from which you can set notifications (for example, when the International Space Station is about to appear). From there, you can also access the Settings menu, which lets you set your location, change the appearance of constellations (add lines or the outlines of mythological figures) and the brightness of the stars that are rendered, and turn music or sounds on and off. Like Sky Guide and SkySafari 5 Plus), when you tap a star while the sound setting is turned on, it will emit a musical tone. The star's name also appears at the bottom of the screen. When you touch the name, an image of the star will pop up, and when you tap an information button ("i"), a description of the star appears.
Running along the left-hand edge of the screen is a slider, which lets you see the sky at different wavelengths. Although you will still see the usual stars, you will also see objects that are only visible at radio, microwave, infrared, ultraviolet, X-ray, or gamma-ray frequencies, and the sky will appear tinted as well.
A search icon (magnifying glass) is located at the main screen's lower-right corner. Tapping it brings up a pull-down menu that by default shows constellations, with the ones above the horizon highlighted in white. By tapping a series of icons along the bottom of the menu, you can access planets and other solar system objects, deep-sky objects (such as star clusters and galaxies), stars, and satellites.
An Essential In-App Purchase
The deep-sky objects, satellites, and many of the solar system objects are only available through an in-app purchase. The basic version of the app doesn't even render deep-sky, showpiece objects easily visible to the unaided eye, such as the Andromeda Galaxy and the Orion Nebula. These objects were not behind a paywall in the original app, which provided photos and descriptive text for them and many other deep-sky objects.
The makers of the app seems all too eager to get users to upgrade through in-app purchases. (You can either buy the all-on-one bundle for $2.99, or up to four individual items for $0.99 each: Deep Space Objects; Extended Solar System; Planets Info Upgrade; or Satellites.) Click on the Sun or a planet, and a message, "Upgrade the Planets," appears at the top of the screen. (Upgrading the planets lets you access 3D renditions of the objects that you can spin, similar to those found in Solar Walk 2.) My reaction on seeing this message was, "What's the matter? Aren't the planets that come with the app good enough?" However, if you are going to buy Star Walk 2, you will want to also spring for the all-in-one bundle (which unlocks all the in-app purchase content), effectively doubling the price of the app.
Star Walk 2 is a pretty app, but its basic version lacks some essential showpiece objects, such as the Andromeda Galaxy. You can add it and a lot of extra content by upgrading to the all-in-one bundle, but that effectively doubles the price of the app. Granted, buying this bundle isn't going to force you into bankruptcy, but with several excellent planetarium apps including Sky Guide, SkySafari 5 (the basic version of the Editors' Choice SkySafari 5 Plus), and Star Chart selling for $2.99 or less, it's no bargain either.