Let’s say you want to plan a camping trip to coincide with an auspicious time to view a meteor shower (like the Persead shower that reached its peak last week). You’ll want to pick a time when the moon is not up. Or let’s say you want to have some friends over for some planetary viewing and a glass of bourbon (as happened last night at the Root Simple compound). In that case you might want to pick a time when you can also take a look at the moon.

In the pre-personal computer era I used to use a planisphere. I still have my 1980s era plastic planisphere. But the planisphere does not show the planets or moon. You’ve got to hunt down that info elsewhere. And my planisphere is so small that it’s hard to use.

Thankfully, there’s a powerful, free open-source solution: Stellarium. Stellarium is a computer based planetarium that comes in OS X, Windows, Linux and Ubuntu versions. You can dial in any place and time. It comes with a catalog of 600,000 stars, eclipse simulation, meteor shower information, telescope control and much more.

How can you use Stellarium with a telescope or binoculars? I face major challenges using my fully manual Dobsonian telescope in light-polluted Los Angeles. It’s very hard to find “deep sky” objects such as nebulae and star clusters when you can, literally, count the number of stars in the sky. Last night I used my old star maps and regretted not loading Stellarium on Kelly’s laptop.

Stellarium comes with a bunch of scripts that function like planetarium shows. You can watch an eclipse or take a tour of suggested celestial objects. Two inventive teachers went so far as to make their own planetarium with cardboard and use Stellarium with a video projector and mirrored dome. This is just about the best school science project ever:

There’s a beneficial feedback loop here. Kids and adults interested in the night sky will advocate for less or better artificial lighting in the future. Dark skies are essential for the health of both wildlife and us humans. Just ponder the conclusive evidence that links artificial light to breast cancer. But there’s also the beauty of a sky full of stars. While computer based, Stellarium might just get more of us outside at night to look up and ponder our place in this amazing universe.