How to use Stellarium Web, the free online star map

Stellarium Web is a free planetarium that runs in your browser: open the site, set your location, and it shows the sky above that place. There is no account and no download. This guide walks through the website as we used it on 6 October 2026, and compares it with the Stellarium app and the free desktop program.

We also checked how accurate the desktop version, Stellarium 26.3, is. Hour by hour through one night, we compared its position for Saturn with NASA's JPL Horizons. The difference stayed between 1 and 23 arcseconds, below the roughly 60 arcseconds the naked eye can resolve. That is one planet on one night, not a full validation.

Web, app or desktop: which Stellarium?

Stellarium comes in three versions that share a name and a look but are not the same product.

• Stellarium Web runs in the browser at stellarium-web.org. It is the quickest way in: nothing to install.
• Stellarium Mobile is the phone app. The free version handled the tasks we tested in our test of six stargazing apps, including showing the sky after a restart in airplane mode. A paid Plus version adds more stars, deep-sky objects and observing tools.
• Stellarium for your computer is the original program: free and open source, for Windows, macOS and Linux, with the most settings and features.

If you are new to stargazing, start with the website to learn the basics, and install the app when you want to hold your phone up to the sky.

Getting started with Stellarium Web

Go to stellarium-web.org. The sky appears straight away. Check the date and time at the bottom right: on one daytime visit the site showed a later evening time instead. On our first visit the location button at the bottom left said Near Amsterdam: the site had estimated where we were. It did not say how.

To set your own location:

• Click the location button at the bottom left.
• Type your town into the search box on the map, press Enter and choose it from the list.
• Click Use this location.

The dialog also has a Use Autolocation switch. A cookie notice appears at the bottom, with only an I agree button; the sky worked without clicking it.

The letters N, E, S and W on the horizon show the directions, and info cards have + and − buttons to zoom in on what you selected.

Find a planet: Saturn tonight

Type a name into the search box at the top, such as Saturn, and pick it from the list. The view turns to Saturn and an info card opens with its brightness (magnitude), its distance in astronomical units (1 AU is the distance from Earth to the Sun) and, most useful, when it rises and sets for your location.

For Maastricht on 12 October 2026 the card gave Rise: 18:43 and Set: 07:05 in Dutch summer time, the set being on the morning of 13 October, with Saturn low in the east-south-east in the evening. NASA's JPL Horizons gives 18:43 for the rise and 07:07 for the set.

The same search works for stars, such as Vega or Deneb, and for the Moon and the other planets.

Turn on constellations and labels

The bottom bar has a row of icons. From left to right they switched, in our session: constellation lines, constellation artwork, the atmosphere, the landscape, an azimuthal grid, an equatorial grid, deep-sky objects, night mode and full screen. Hover over an icon to see its name.

• Constellation lines connect the main stars and add the names, the easiest way to learn the sky.
• Constellation art draws the classic figures, such as the Great Bear. It looks beautiful, but switch it off again when you want to see faint stars.
• Turning off the landscape lets you see what is below the horizon; turning off the atmosphere shows the sky as if it were fully dark.

With lines and names on, Gemini is easy to find in December. Our Geminid meteor shower guide shows where its radiant is and the best hours to watch.

Night mode and moving through time

Outside, a bright white screen ruins your night vision for minutes. The eye icon in the bottom bar switches to night mode: the sky and the controls turn red, which disturbs dark adaptation much less. In our screenshot the cookie notice stayed grey.

Click the date and time at the bottom right to open the time panel. It has arrows above and below the numbers and a slider; in an earlier session we moved through the night with the slider. The label under the slider tells you how dark it is, for example Dark night.

This is how you plan: set the date of a meteor shower or a clear evening, and see what will be up and where. For the total solar eclipse of 2 August 2027, our eclipse guide lists the predicted times for 30 places.

Find the Milky Way

Stellarium shows the Milky Way, so you can use it to see where to look. At 21:00 on 12 October 2026, seen from Maastricht, Deneb in Cygnus, the Swan, stood almost straight overhead (about 84° high), and the Milky Way ran through it and down towards the south-west. Later in the evening and later in the season it moves further west.

The easiest way to find it in Stellarium Web is to search for Deneb, the brightest star in Cygnus, for your own date and time. Turning off the atmosphere icon makes it stand out more on screen.

In real life you need a dark place, away from street lights, and a night without a bright Moon. Stellarium's time panel shows when the Moon is up.

Stellarium on your phone: free or Plus?

Stellarium Mobile works much like the website, with one big extra: it is designed to follow the direction you point your phone in. We did not test that outdoors. In our test of six free stargazing apps the free version found Saturn, showed when it is visible, had a red night mode in the layers panel and kept working in airplane mode. Google Play lists no ads for it.

The free version does show offers. While zooming in, banners appeared for "high resolution planet textures" and "a massive collection of sky objects", and the calendar and observing tools carried a lock. The upgrade screen offered Stellarium Mobile Plus with a 7-day free trial, then €2.39 a month, or €19.99 as a one-time purchase (prices shown to us on a Dutch Google account on 5 October 2026).

For most beginners the free version is enough. Plus makes sense if you use it a lot and want the extra objects and planning tools.

Stellarium on your computer

The desktop program is the most complete version and it is entirely free: stellarium.org offers version 26.3, released on 28 September 2026, for Windows, macOS and Linux. We installed it on Windows; the installer was 466 MB.

What it adds:

• Much more detail and settings, such as the full data list for any object.
• Plugins that were included in our install, for example for satellites, meteor showers, exoplanets and Oculars, which simulates the view through a telescope eyepiece.
• Scripts, which we used to set exact places and times for the screenshots in this article.

How accurate is Stellarium? We checked the desktop version

For the night of 12 to 13 October 2026 we asked Stellarium 26.3 for Windows where Saturn would be, every hour from 17:00 to 05:00 UT (Universal Time, two hours behind Dutch summer time), as seen from Maastricht. We asked NASA JPL Horizons, the ephemeris service of NASA's Jet Propulsion Laboratory, the same question for the same place and times, including the bending of light by the atmosphere.

An arcsecond is 1/3600 of a degree. For comparison: the sharpest detail the naked eye can see is about 60 arcseconds, and the full Moon is about 1,800 arcseconds across. The largest differences were close to the horizon, which is consistent with differences in how the two model the bending of light by the atmosphere; we did not test that separately.

We also looked at Saturn's height in Stellarium at the minutes NASA gives for its rise (16:43 UT), its meridian transit (22:55 UT) and its set (05:07 UT on 13 October). The differences were 31, 1 and 32 arcseconds.

For finding planets and stars by eye, differences this small do not matter. This was one planet on one night with the desktop version; we did not test the website or the app in the same way.

Stellarium Web FAQ

Is Stellarium Web free? Yes. We used it without an account or payment. The site shows a cookie notice and promotes the Stellarium Mobile app.

Is Stellarium real or fake? It is a real, long-running astronomy program. The desktop version is open source on GitHub, and in our hourly comparison its positions for Saturn matched NASA's to within 23 arcseconds.

Which is better, Sky Map or Stellarium? Sky Map is simpler and has no paid upgrade; Stellarium shows more detail and works on the web, phone and computer. We compared both, and four other apps, in our stargazing app test.

How do I turn on constellations in Stellarium? On the website, click the first icon in the bottom bar for lines, and the second for artwork. In the app, open the layers panel at the bottom left.

Does Stellarium show the Milky Way? Yes. Search for Deneb to find the bright part through Cygnus on autumn evenings.

Does Stellarium Web work offline? It is a website, so you need a connection to load it; we did not test what happens when the connection drops. The app showed the sky after a restart in airplane mode in our test, and the desktop program is installed on your computer.

Is there a free version of Stellarium? Yes, three: Stellarium Web in the browser, the free version of the Stellarium Mobile app (with an optional paid Plus upgrade) and the desktop program, which is free and open source.

What constellations are visible in the sky tonight? That depends on where you are and the time. Set your location in Stellarium Web, switch on constellation lines, and it draws the constellations above your horizon right now. Our Tonight page shows when it gets dark where you are and which bright planets are up.

What exactly does a planetarium show? A planetarium program like Stellarium draws the sky as it looks from a chosen place and time: stars, planets, the Moon, constellations and the Milky Way. You can move through time to see how the sky changes.

How we checked

We used Stellarium Web in Microsoft Edge on 6 October 2026, Stellarium Mobile 1.16.8 on a Samsung Galaxy S25 Ultra with Android 16 on 5 October 2026, and Stellarium 26.3 for Windows, downloaded from the official release linked on stellarium.org. For the website screenshots we used a fresh browser profile and set its clock to 12 October 2026, 21:00 in the Netherlands; we did not click the cookie notice. The desktop screenshots were made with Stellarium's own scripting for Maastricht at the same time. The phone screenshots come from our app test on 5 October 2026, with an approximate location in the south of the Netherlands.

For the accuracy check we queried NASA JPL Horizons on 6 October 2026 for Saturn's refracted azimuth and altitude from 50.8514° N, 5.6910° E, 50 m, hourly between 17:00 and 05:00 UT on 12 to 13 October 2026, plus its rise, transit and set times. We asked Stellarium 26.3 for the same values with the atmosphere switched on and compared them. Stellarium's info panel also lists rise and set times rounded to the minute; because we did not establish exactly how it defines those, we compared positions rather than those labels.

Prices and in-app offers are what the app showed us on a Dutch Google account on 5 October 2026 and can change.

The screenshots are our own captures, scaled down and cropped, but they show Stellarium's imagery and data. Stellarium Web credits Gaia, Hipparcos and the Bright Star Catalogue for its stars, the Digitized Sky Survey (STScI/NASA, coloured by CDS) for the sky background, NASA/JPL for planet images, Fabien Chéreau for landscapes and constellation lines, and Stellarium Labs for other graphics. In the desktop program the constellation artwork is by Johan Meuris under the Free Art License, the Saturn texture is by Oleg Pluton (CC BY 4.0) and the Milky Way panorama is by Axel Mellinger. Stellarium Mobile is published by Noctua Software. The object descriptions in the info cards come from Wikipedia (CC BY-SA). The map in the location screenshot is © OpenStreetMap contributors. Stellarium Labs confirmed by email on 7 October 2026 that this use of the screenshots is fine, and asked for a credit with a link to their apps: Stellarium Web and Stellarium Mobile for Android and iPhone and iPad. The desktop program is at stellarium.org. Stellarium's FAQ also notes that some images and data are copyright of others; the credits above follow Stellarium's own lists. We left out views showing artwork or imagery whose licence we could not find, and we did not check the app's own credits list. The chart and diagram were made by us from our own measurements. None of the images is AI-generated. We will add a dated note when we notice a material change.