Since the dawn of time, people have sat outside at night, gazed up at the stars, and said: "What the heck do you suppose is going on up there?" They've also said: "Boy, my neck hurts. And it's cold. And I'm bored. And things are hard to see. And stop calling that one Leo, it doesn't look a bit like a lion."
Well, you won't be saying any of those things once you've installed Sienna Software's Starry Night Backyard on your computer (see "Stars on the Cheap" in TidBITS-306 for a brief review of the initial version of Starry Night). You'll be enjoying instant gratification of your curiosity: if you want to understand the retrogradation of Mars or why the moon has phases, you'll just fly up above the solar system and watch how it happens. You'll be able to look in all directions without turning your head. You'll be able to see more stars than you could with the naked eye on the clearest night. You'll see several ways of drawing each constellation. And you'll be warm and comfortable inside your own home.
Starry Light, Starry Bright -- Starry Night Backyard is the "light" version of Sienna's Starry Night Pro, and is aimed at beginners, young people especially. To this end, it stresses realism and ease of use, and to its great credit, it takes only a moment or two to understand the program and begin exploring. At startup, a full-screen window opens, showing the present view facing south from your home; grass and trees make up the lower half, and above, if it is daytime, there is blue sky, which you can remove by unchecking Daylight from the Sky menu. You can also adjust the level at which dimmer objects are filtered out, for an accurate simulation of your actual nighttime view. Apart from this, you'll barely need the menus at all, since everything is ready to hand. To turn your virtual head, drag the cursor to "grab" and shift the view. Across the top of the window are a series of small fields and buttons, which you can use to change the time, date, and location, alter your height, magnify the scene, or control time-based animation. Animation is normally "live," but you can set it to various step sizes and animate forward or backward, continuously, or by single-step. You can also make QuickTime movies where each animation step is a frame.
Menus let you toggle the display of names for various classes of celestial object; you can also show constellation names, boundaries, and various stick-figure renderings. But you don't need any of this to learn what you're seeing: as you pass the cursor over an object, its name and some other basic information pops up; double-clicking the object displays a separate dialog with details about it, including its coordinates and rise/set times. To find an object, just type its name into a dialog box. If you hold the cursor down on an object, a contextual menu appears, where you can do things like show the orbit (for a planet), or "lock" the object so that it remains steady as the window animates. For example, an easy way to watch Mars retrograde is this: find Mars and lock on it; animate a day at a time, watching the background of stars until it pauses, then back up several days; now lock on a nearby star to hold the background steady, and animate one sidereal day at a time.
There are various ways to get a different perspective. You can choose from the Go menu (for example, you can take a position looking down on the inner solar system), or select an object and choose Go There from its contextual menu. Multiple undos let you return easily from an exploration. Combining the ability to Go There with the capability to change elevation and to animate lets you create some wonderful effects. For example, it's a simple matter to fly through the solar system on the back of Halley's comet. First, Go There, and elevate yourself some way above the comet's surface. Now find the Sun and lock on it. Then, to find the next fly-through, animate in month steps: when you see some popping and flashing, that was it! Single-step back a few times, turn on planetary orbits to give yourself some orientation, change to one-day steps, and enjoy the ride - better than any roller coaster.
The View from Up There -- A particularly nice aspect of Starry Night Backyard's realism is its use of what I call secondary animation. When you ask to find an object, it doesn't just magically appear; the view pans round to it, as if you were turning your head. When you change your field of view or elevation, or Go There, the image doesn't just change: you fly in a continuous motion, which gives a sense of the relative sizes of things. For example, when you Go There from Earth to Halley's, the earth drops away, then there's a pause as you rise slowly out of the inner solar system, then there's a longer pause during which nothing seems to happen as you cross the outer reaches of the solar system, and finally you approach Halley's, where, as the comet starts to loom as a globe, you suddenly see your own feet (appropriately clad in a space-suit, of course) as you drop in for a landing.
Also, conceptual or photographic images of various objects are included, so that if, for example, you go to Mars, or zoom in on the Orion Nebula, you really get to see something. Plus, astronomy being one of those subjects that's extremely well documented on the Internet, Starry Night Backyard can send you online via links at Sienna's own livesky.com site, and any URLs you like can be made part of an object's contextual menu; thus, images and information on the Internet become virtually incorporated inside Starry Night.
Getting Back Down to Earth -- Starry Night Backyard is a wonderful introduction to the marvels of the heavens, but it also has some infelicities of interface which seriously hamper its suitability for the young audience at which it is ostensibly aimed. Choosing from the Go menu resets the date and time to now, so when you jump up above the solar system to get a look at an interesting event you've carefully set up from earth, the event isn't there any more, which is confusing. Selecting a celestial object, to display its name or bring up its contextual menu or information dialog, is physically extremely difficult, because your cursor isn't given enough tolerance: you have to get it right smack on the object.
The program underemphasizes the quantitative aspect of astronomy: you're shown some numbers as you fly or zoom, and you can learn angular separations by dragging, but you can't locate an area of the sky by inputting coordinates, or even display the coordinates of the point under the cursor. Also, you can project the celestial grid onto the sky, but not the local (horizon-based) grid, which is a great pity because the relationship between these is the first thing a budding astronomer needs to understand. Animation time steps can be set only in gross integral units, and rising and setting times are given to the nearest minute only, making it hard to gain an understanding of such phenomena as day length. There is no readily available "trails" feature; you can trace the path of a retrograde, but it requires extreme trickery (I figured it out only by accident).
There is no indication that a menu item may involve the Internet, and many do, so you're stunned when you choose a command and your browser opens (and the command fails, because you're not connected). The printed manual is somewhat incomplete; menus and help buttons lead you to believe there's an online manual, but they lie. Finally, I should mention that of my many sessions with Starry Night Backyard, about 80 percent ended in the program freezing or crashing, and forcing a restart; however, this may have been some sort of extension conflict.
The Joy of Rediscovering Space -- There are other, more mathematically oriented sky programs - I'm a particular fan of Southern Stars' SkyChart, which I've been using since it was shareware - and of course if it's just numbers you want, it's no longer difficult to get your computer to calculate them. But as an inexpensive program with realistic visuals, great ease of use, and attractive bells and whistles, Starry Night Backyard is certainly a remarkable value. The catalog of included objects seems quite generous, running down to some objects of magnitude 11 or 12 (fainter than can be seen with the naked eye or binoculars). Its feature set is brilliantly geared towards education and exploration. It's attractive, enticing, and fun.
Starry Night Backyard requires System 7.5, QuickTime, and a PowerPC-based system. It occupies about 85 MB installed. It costs $65, or $50 for the online version. A time-limited demo is available for download.