Why use Stellarium on a laptop?
Stellarium is free software that runs on Windows, Mac OS X and Linux, so a laptop can run the same planetarium program on whichever system you already use. Compared with a phone, tablet or printed chart, a laptop gives a larger screen for reading object labels and menus, and a mouse and keyboard let you move across the sky and select objects more precisely than touch input. A printed chart is fixed to one date and location, and a phone screen is small, so a laptop is useful both for planning a session indoors and for reference at the telescope.
Free on Windows, Mac OS X and Linux
The same program works across all three systems, so the planning habits you build on one laptop carry over if you switch machines.
A larger screen for charts and menus
Stellarium displays star labels, object names and its settings menus on screen, and these are easier to read on a laptop display than on a phone. The View settings window, opened with F4, controls star size, labels, magnitude limits and light pollution. Adjusting these on a larger screen makes it simpler to check which objects will be visible from your location.
Mouse and keyboard control
Keyboard shortcuts and mouse clicks handle most navigation. The following controls are reported by BBC Sky at Night Magazine:
| Action | Control |
|---|---|
| Open search | F3 |
| Centre a found object | Return |
| Centre a clicked object | Spacebar |
| Open view settings | F4 |
| Open Configuration Window | F2 |
The Configuration Window also holds the default startup time in its Navigation tab, which lets you set a fixed starting time rather than the computer’s current time.
Install and set your location
You download Stellarium from stellarium.org, install it, and then tell it where you are. The simulated sky depends on your location, so set it before you plan an observing session. Click the compass icon on the left toolbar, or press F6 in the version described by the source (shortcuts can differ between versions), to open the location window. From there you can choose a spot on a map, type a town or city, or enter exact latitude and longitude.
Download and install
- Go to stellarium.org and choose the build for your operating system: Windows, Mac OS X or Linux.
- Check the system requirements listed on the download page before installing, especially on older machines.
- Install and launch the program. The first launch can take longer while the sky data loads.
Open the location window
- Press F6, or
- Click the compass icon on the left toolbar.
Set your position
Stellarium offers three ways to set your position:
| Method | What to do | Best when |
|---|---|---|
| Map position | Click a spot on the map | You know roughly where you are and need a quick setting |
| Town or city | Type the name and pick the match from the list | You observe from a known settlement |
| Coordinates | Enter the exact latitude and longitude | You observe from a specific site, such as a dark-sky location or your back garden |
For a dark-sky site or a fixed observing spot, coordinates are the most precise option. Read them from a map or GPS device, and check the sign convention the window shows before confirming. Once you confirm, the sky view updates to match your site.
Set the date and time
Stellarium starts with the sky for your computer’s current time. A daytime launch therefore shows a daytime sky, with the Sun up and most stars hidden. To view a chosen evening, a past event or a future date, change the simulated time inside the program. Your system clock stays as it is.
Why a daytime launch shows a daytime sky
The program reads the computer’s clock at startup and draws the sky for that moment. If the clock reads midday, the view is midday, whatever the real night sky looks like. The simulated time is separate from the clock, so you can change it without altering your computer.
Methods for changing the time
| Method | Effect |
|---|---|
| Press F5, or click the clock icon | Sets the date and time shown for the current session |
| Configuration Window (F2), Navigation tab | Sets a default startup time used on each launch |
| No default set | Stellarium uses the computer’s current time on launch |
Setting a date and time with F5
Press F5 or click the clock icon. Enter the date and time you want, then apply them. The sky redraws for that moment, and you can use the same control to jump to a future eclipse, a past meteor shower peak or any other date you need to check.
How do you set up night mode for outdoor use?
Stellarium’s red night mode is the main display setting for outdoor sessions. It changes the window’s colours so that less bright light reaches your eyes, which helps your pupils stay open and your night vision keep its sensitivity. Combined with a lower screen brightness and a short check before you leave the house, it lets you read charts and star names without undoing the dark adaptation you have built up over the previous 20 to 30 minutes. The steps below cover the red display, the reasons behind it, and the laptop brightness settings to make before you step outside.
Turn on the red display
The eye icon sits on the bottom toolbar. Clicking it tints the entire Stellarium window red, which is the night mode. Click it again to return to the normal colour view.
Why red light preserves dark adaptation
Dark adaptation depends on the light-sensitive cells of the retina, which need time to become sensitive to faint light. A bright white screen resets much of that sensitivity within seconds, while red light has a smaller effect on the same cells. This is why red display modes are used in observing sessions. Red does not make the sky brighter, and it does not change which stars you can see at a given site.
Set laptop screen brightness before observing
- Lower the display brightness to the minimum that keeps the chart legible.
- Turn off any automatic brightness adjustment so the screen does not change brightness unexpectedly during the session.
- Close other windows, notifications and bright applications so that no white areas appear on screen.
- Angle the screen so it is readable only from where you sit, and shield it from the eyepiece side with a cloth or hand, so that the glow does not reach your eyes.
Find and identify objects
Once Stellarium is centred on your location and the sky is set to the correct time, the search tool is the fastest way to locate a specific target. Press F3 to open the search field, type the name of the object (for example a planet, a star or a deep-sky object), and press Return. Stellarium centres the view on the matching object, so you can confirm it on screen before you move the telescope or step outside.
Searching is the fastest route to a named target, but a target that is already visible on screen can be centred another way. Click the object to select it, then press the spacebar. The view slides to place that object at the centre, which is useful when you spot a bright point in the sky and want to check its name.
Adjust light pollution and sky settings
Stellarium’s light pollution and magnitude controls determine how many stars the simulated sky shows, so they must match your real observing site. Open the view settings with F4, set the light pollution setting to your local conditions, and adjust the limiting magnitude until the screen matches what you can see from your garden, balcony or observing spot. A mismatch means the software shows stars and faint objects that your eyes will not pick up.
Where the controls are
| Control | Where to find it | What it changes |
|---|---|---|
| Light pollution | F4 view settings | Sky brightness in the simulation |
| Magnitude limits | F4 view settings | Faintest stars drawn on screen |
Match the limiting magnitude to your site
The limiting magnitude is the faintest star your eyes can detect under your sky. Stellarium draws stars only down to the limit you set, so a value that is too high shows a crowded sky.
- Step outside and let your eyes adjust to the dark for 20 to 30 minutes, avoiding white light.
- Pick a constellation that is up at the time.
- Count the stars you can see in that area.
- Adjust the magnitude limit in F4 until the same area on screen shows a similar number of stars.
Repeat the check on a different night or at a different altitude if your site changes.
Pick a Bortle class for your site
The Bortle scale rates a site’s night-sky brightness from excellent dark sky to inner-city glow. The Stellarium User Guide includes a Bortle scale appendix that runs from “Excellent dark sky site” to “Inner-city sky”. Read the descriptors in the appendix, choose the one that best fits your location, and set the light pollution value to match. Check the official guide for the exact class wording and the settings it recommends.
Which plug-ins help observers?
Stellarium includes optional plug-ins that extend the core sky view. Three are relevant at the eyepiece: Oculars, which simulates eyepiece and camera fields of view; Satellites, which can track objects such as the International Space Station; and TelescopeControl, which handles connecting a mount. According to BBC Sky at Night Magazine, Oculars and Satellites are the plug-ins to know for field framing and satellite tracking. The official Stellarium 26.2 User Guide (Stellarium project, 2026) includes a TelescopeControl section.
| Plug-in | What it does | Use it when |
|---|---|---|
| Oculars | Simulates eyepiece and camera fields of view | Checking whether a target fits your eyepiece or sensor |
| Satellites | Tracks objects such as the ISS | Following a satellite pass across the sky |
| TelescopeControl | Connects Stellarium to a telescope mount | Pointing the mount at the object shown on screen |
Framing targets with Oculars
Oculars shows the field a given eyepiece and camera combination would cover, so you can judge before a session whether a target will fit in the view. Enter your telescope and eyepiece details in the plug-in settings, and check the values against the labels on your equipment.
Following the ISS with Satellites
The Satellites plug-in can track objects such as the ISS. Check the official User Guide for how to enable it and display the station in your installed version.
Connecting a mount with TelescopeControl
The sources available for this guide confirm that TelescopeControl exists and has a section in the official User Guide, but they do not confirm the setup steps. Read that section and check which connection method your mount supports in the manufacturer’s instructions before you rely on it.
Take your laptop to the field
Running Stellarium outdoors means managing three things: battery charge, the effect of cold on the battery, and where the screen sits relative to your eyes. Plan power before you leave, keep the machine insulated until you need it, and position the screen so you can read it without losing your night vision.
Battery life and mains power planning
Start the session with a full charge, but don’t assume the battery will last the whole night. Use mains power whenever the site has an outlet:
| Situation | Power approach |
|---|---|
| Site has an outlet | Use the laptop’s own charger and an outdoor-rated extension cord long enough to reach your observing spot, keeping plugs and connections off damp ground and away from dew. |
| No outlet | Use a power bank, checking that its output matches your laptop charger’s rating on the label. |
| Long session | Close other programs and disable Wi-Fi and Bluetooth if you don’t need them. |
Before leaving home, set Stellarium’s location (F6) and date and time (F5) while still indoors.
Cold temperature effects on laptop batteries
Cold reduces the charge a laptop battery can deliver, so a battery that lasts hours indoors can shut down earlier on a cold night. Keep the laptop in a bag or inside your coat until you set up. When you bring it from the cold into a warm room, condensation can form on and inside it, so let it reach room temperature while closed before powering on. Check the operating temperature range in the manufacturer’s manual or support pages.
Laptop placement at the telescope or chair
Put the laptop on a stable table or the chair’s tray, at a height where you can read the screen with a small head movement rather than bending over it. Position the screen off to one side so it stays out of your line of sight when you’re at the eyepiece. Route cables away from the focuser and the mount’s movement path so they don’t snag or tug on the telescope.
