As we entered the 21st century it seemed that computers had worked their way into just about every aspect of our daily lives. Astronomers with their nightly lives have computers to thank for various benefits as well.

Amateur astronomers enjoying the starry canvas overhead certainly don’t need computer assistance, but astronomical software can nevertheless greatly enrich your skygazing. If you partake of some of the digital tools outlined below, you may find yourself exploring unexpected corners of the cosmos and perhaps eventually concede that you can’t spend the night outside without such electronic help.

Astronomical software is practical because nearly everything in the sky is predictable — the schedule just requires a lot of calculations. Before the popularity of the personal computer, few amateur astronomers were up to the task of determining celestial motions. Thus, they relied on almanacs, publications in which someone else had done all the work.

The primary benefit of using your own software is flexibility. A chart like those in a magazine or book is ideal for certain dates, times, and viewing locations. For more variety, a planisphere, or “star wheel,” will present the sky overhead for any date and time — but it’s nevertheless best for a specific latitude. Software goes one step further and will show how the sky appears at any time, date, and place. After you set your virtual sky the way you want it, you can save the results, say, by printing a copy of a chart to take with you under the stars.

Galaxy of Choices

Astronomical software comes in a variety of packages, ranging in price from free for the Internet download to costing several hundred dollars. (Many programs in the not-free category can be examined at no charge using a downloadable demonstration version.) The breadth of software is wide; some can serve as electronic planispheres — often called “desktop-planetarium” software — or as incredibly detailed star atlases. Some products go far beyond these basic mapping features, such as helping you plan and record your observations and controlling a telescope and an electronic camera.

Among the celestial information that such programs can provide are identifying stars and constellations from your backyard, locating the planets, determining the date of the next full Moon and whether any eclipses occur, and visualizing the new regions of the sky that you’ll see on your next vacation.

As a first step in exploring astronomical software, check out SkyandTelescope.com’s online Interactive Sky Chart. Once you initialize the utility by telling it your location, it will present the current evening’s sky, complete with the constellations, Moon, planets, and a few nebulae, galaxies, and star clusters.

Move your cursor over the circular map to highlight constellations and click it to show detail in the Selected View window. Modify the time, date, and location to see how powerful astro software can be. Go forward or backward in time by hours, days, or years. Be sure to also check Fun with S&T’s Interactive Sky Chart, which surveys other ways to take the utility for a test drive. (Unfortunately, the Interactive Sky Chart doesn’t work with all variations of computer operating systems and Web browsers.)

Pop over to SkyandTelescope.com's Resources section and the Astro Software menu. There you’ll find helpful listings that reveal the variety of available software. One page provides a collection of free or shareware (“try-then-buy”) offerings; another notes the contacts and websites for several commercial software companies. You’ll soon realize that you have a lot of choices.