Stellarium Web is a free planetarium in your browser: a realistic starry sky from your exact spot on Earth, in real time. The desktop Stellarium has been the standard among amateur astronomers for over twenty years, and the web version needs nothing but a browser tab. Here are three experiments worth doing in your first fifteen minutes.
Experiment one: what is that shining over the horizon
Let the site detect your location or set your city manually — and there's the sky you'll see out the window tonight. That bright "star" above the horizon you noticed yesterday? Click it. Odds are it turns out to be Venus or Jupiter — and the planetarium instantly shows the name, distance and brightness. Turn on constellation lines and the chaos of dots snaps into familiar figures. Then search for M31: the Andromeda galaxy, the farthest object the naked human eye can see — 2.5 million light-years.
Experiment two: the sky on the day you were born
Stellarium's superpower is time control. Set your birth date and see where the planets stood. Jupiter circles the Sun in 12 years, Saturn in 29, so their arrangement in the sky is almost a personal fingerprint of a date. Fast-forward time and watch the planets trace loops among the stars — the very loops that once drove astronomers mad and eventually led to the heliocentric model.
Experiment three: the evening of August 12, 2026
Now set the date to August 12, 2026. That evening Europe gets a total solar eclipse — the path of totality crosses Iceland and Spain, with partial phases visible across much of the continent. And that same night, the Perseid meteor shower peaks under a new Moon — the best meteor conditions in years. Set your city, bring the Sun to the horizon and check for yourself what will be visible from your balcony. The planetarium replays it to the minute.
Why bother
Stellarium turns the abstract "stars are somewhere up there" into the concrete "that one is Vega, and tomorrow at 9:40 pm Saturn rises over the roof." The sky becomes readable. Runs in the browser, free, on your phone too.
