SkySafari 3 is the junior (and at £1.99 the lowest priced) of three iPhone planetarium apps from Southern Stars, but there's nothing inferior about it. It provides a visually appealing and relatively realistic look at the night sky. It has a wealth of features that set it apart from similar apps in its price range, and is a clear pick for a Best Buy award.
As a planetarium program, SkySafari shows a map of the night sky, with stars, planets, and other objects, matching the view in the direction you're pointing the phone. It does this by utilising the phone's compass and GPS. It even shows the stars in daylight, though of course they're masked by the Sun's glare in reality.
Also in the same line, Southern Stars offers SkySafari 3 Plus (£10.49), which adds more and fainter objects, and SkySafari 3 Pro (£27.99) is similar to the Plus version but adds features like the ability to point a telescope via Wi-Fi.
One thing that sets SkySafari 3 apart is its wide range of adjustable settings. Along the bottom of the screen, when held in portrait orientation, is a bar with a row of labelled icons. If you swipe the bar to the left, a few additional ones will appear. They are labelled Search, Info, Centre, Settings, Time, Compass, Gyro, Night, SkyWeek, and Help.
The Search function contains stars, constellations, planets, deep-sky objects (galaxies, star clusters, nebulae) and more, in drop-down menus. Objects below the horizon are greyed out. The first list, Tonight's Best, shows the night's finest objects in a combined list including the moon, several planets, and many galaxies, nebulae, star clusters, and double stars.
One search list lets you identify artificial satellites as they track across our sky, and another displays the first 100 numbered asteroids (including most of the brightest ones) plus asteroid #712 (Boliviana).
A number of comets also reside in the database. Tapping on any of the objects in these lists pulls up a page of data on it, and then pressing Centre takes you to the object. I was able to use SkySafari to locate the recent comet PanStarrs when it was low in our light-polluted New York City sky and hard to make out, even with binoculars. Few low priced astronomy apps show comets (or indeed satellites) at all.
Tapping on any object in the planetarium view will identify it by name or designation (for example, the star HD 113458), and then tapping the Info icon displays details such as alternate designations, celestial coordinates, visual magnitude, distance, and physical characteristics (which vary depending on the nature of the object).
Planets appear star-like, and more or less at their true apparent brightness relative to each other and the stars. If you really zoom in on a planet, it will eventually show as a disk. This is a welcome change from the programs that represent planets solely with small thumbnail images, and all at the same size.
By tapping on a planet and pressing the Info icon, you can access data about it, including its apparent magnitude (brightness). Touching the Description button will then give you a brief overview of that planet, as well as a link to an image of it. Other apps such as GoSkyWatch Planetarium give numerical magnitude data but show little images of each planet rather than trying to depict their brightness visually.
The Info and Description features work similarly for other objects: Bright stars, comets, asteroids, and deep-sky objects such as galaxies and star clusters. In some cases, you can't access the image; you'll get a message that it's only visible in SkySafari 3 Pro. Fainter objects will include info, but no description.
Pressing the Centre button will bring whatever object you've highlighted to the centre of the field. From Settings you can change a range of settings, including date and time, location, field of view (in degrees), chart and sky appearance, and how various types of objects are depicted.
Pressing Time lets you see how the sky changes when you move forwards or backwards in time. You can move either incrementally, or set time flowing at a fixed rate. Pressing Compass will realign the sky to correspond with the compass direction. The Night icon puts the app into night vision mode, in which the screen is red and the stars muted, to preserve your dark adaptation.
There's very little not to like about SkySafari 3. Though moderately priced, and the junior of the three SkySafari apps, it's powerful, providing data on even the faintest stars it shows, and descriptive information on many brighter objects. Its sky depictions are both pleasing and accurate. It doesn't show stars quite as faint as the Starmap iPhone app, but what it does show is fine for most observation with binoculars or a small telescope.