I loved the astronomy app SkySafari 3 (for iPhone) enough to make it an Editors' Choice when I reviewed it in early 2013. It's even more stunning when used on the larger screen of an iPad, and easily takes the Editors' Choice honor for use on that platform as well. It combines an attractive interface, a wealth of features, a wide range of observable objects, and data on every object it shows.

SkySafari is what is known as a planetarium program, as it presents a depiction of the night sky in the direction you're holding your iPad. It does so night or day, and whether it's cloudy or clear. This virtual planetarium's "dome" is the sky itself. You can stretch the screen to zoom, or pinch it for a more wide-field view.

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SkySafari Basics
The app's depiction of the night sky rightfully fills nearly the whole screen. Along the top are location (latitude and longitude) and date, as well as info about the sky view's scaling and the direction you're pointing. Along the bottom of the screen, when held in portrait orientation, is a bar with a row of labeled icons. If you swipe the bar to the left, a few additional ones will appear. They are labeled Search, Info, Center, 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 grayed out by default, though you can set it so the area below the horizon is transparent (making the sky one continuous sphere) or translucent.

The first search list, Tonight's Best, shows many of the night's more impressive objects in a combined list that includes the Moon, planets, and many galaxies, nebulae, star clusters, and double stars. Other lists include Comets, Asteroids, Satellites, Brightest Stars, Named Stars, Deep-Sky Objects, Constellations, and more.

The SkySafari Family
SkySafari 3 works on the iPad, iPhone, and iPod touch; I tested it on an iPad 2. It is the lowest priced of 3 similar programs from Southern Stars.; SkySafari 3 Plus ($14.99) and SkySafari Pro ($39.99) are geared to serious amateur astronomers, and let users control a telescope with GoTo functionality with them. All three versions are also available as Android apps, as well desktop programs for Mac OS X.

The Plus and Pro versions of SkySafari have progressively larger star and object databases. But even the basic version under review here shines brightly in the universe of astronomy apps. It shows about 120,000 stars down to fainter than magnitude 9 (about what I can see in binoculars under a suburban sky), with even fainter deep-sky objects (galaxies, star clusters, nebulae) charted. The basic version of the StarMap app shows more and fainter stars, but fewer deep-sky objects. SkySafari 3 shows about 135 asteroids to StarMap's 50. SkySafari tracks more than 150 artificial satellites, while StarMap shows only one, the International Space Station.

All This and Comets, Too
SkySafari 3 has a healthy database of more than 200 comets, including currently visible objects such as Comets ISON and Lovejoy, while the standard StarMap version, as well as most basic planetarium programs, lacks comets altogether. (Comets are available as a $1.99 in-app purchase to the free Star Chart app; I bought this add-on, to be presented with a paltry 17 comets, including ISON, and Halley, which won't be visible to observers again for several decades.)

Another of SkySafari 3's strong points is the thoroughness of the information that it provides. 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 will reveal about it: alternate designations, celestial coordinates, visual magnitude, distance, and physical characteristics (which vary, depending on the nature of the object).

It Gets Planets Right
Planets are shown with their size corresponding to their brightness. This is a welcome change from most planetarium programs, which show all the planets at the same size. If you really zoom in on a planet, it will eventually show as a fairly realistic depiction of the world By tapping on a planet and pressing the Info icon, you can access data about it, including its apparent magnitude (brightness). Touching the Description will button will then give you a brief overview of that world, as well as a link to an image of it.

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 may include info, but no description.

Pressing the Center button will bring whatever object you've highlighted to the center of the field. From Settings you can change a range of settings, from date and time, to location, to the 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 forward or backward in time. You can move either incrementally to view a particular date and hour, 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. SkyWeek gives you Sky & Telescope magazine's list of sky events for the week. Help provides information on the app's various functions.

SkySafari 3 stands out among consumer-level iPad planetarium apps for the variety of objects it shows and the thoroughness of the information it provides for each object. Its sky depictions are both pleasing and accurate. Whether you want to learn the constellations, spot satellites, or view star clusters, galaxies, comets, and asteroids with binoculars or a small telescope, the well-rounded SkySafari 3 and an iPad is all you need to get started.