A universe in your browser

From the sky above
to worlds beyond.

Look up at the stars. Fly toward a planet. Stand on the Moon.
SIDEREUM is a free web planetarium for exploring the universe, right in your browser.

Start exploring ↗See what you can do ↓

Free · No account needed · Currently in beta

Earth rendered in SIDEREUM, showing clouds and the boundary between day and night — An actual SIDEREUM capture. Earth, seen from space.

Explore in your browserDesktop & smartphone日本語 / English

Explore SIDEREUM

One universe.
Many ways to explore.

Distant planets or tonight’s sky. Choose a place, change the time, and see familiar worlds from a different point of view.

The ground view showing stars, constellation lines and labels — The sky from the ground, with constellation lines to guide you.

01 / LOOK UP

Find your way around the sky.

Choose a location and time to see its sky. Turn on constellation lines and star names, or search for an object that catches your curiosity.

Open the sky ↗

The Moon view showing lunar terrain beneath a starry sky — The Moon view. A different place to look up.

02 / GO BEYOND

Leave Earth. Look up from the Moon.

Approach planets and moons in Space view, then see the sky from the lunar surface. Change the time and viewpoint to discover a scene you have never seen before.

Visit the Moon ↗

03 / TAKE IT OUTSIDE

Point your phone. Follow the stars.

In AR mode, the sky follows your phone’s orientation. Compare the display with the real sky to find stars and constellations around you.

Start exploring ↗

Actual smartphone screenshot of AR mode showing Orion and other constellations — Captured on a real smartphone. This is an orientation-driven sky display, not an overlay on a live camera image.

Requires supported orientation sensors and permission to use them. If the heading is off, drag the sky to align it.

Take a guided tour

Learn the controls or follow a tour of celestial sights. Start with “View the guide” on the welcome screen.

Travel through time

Open an event from the sky calendar. Move time forward or backward and watch the sky change.

Share a discovery

Save a favorite view as an image, or share a link to the scene so someone else can explore it too.

Your first flight

Start with a world that interests you.

Open
No installation or account is needed. Choose “Start exploring” to launch SIDEREUM in your browser.
Try the controls
Drag to rotate and use the wheel or pinch to zoom. Tap a celestial body to approach it in Space view.
Keep exploring
Follow the welcome guide or find guided tours in the menu. On supported phones, choose AR from the view selector.

Good to know

Before you set off.

Is it free? Do I need an account?

The current web version is free to use and requires no account. SIDEREUM is in beta; features and visuals may change.

What devices can I use?

You need a desktop or smartphone browser with WebGL support. Performance depends on your device. AR also requires compatible orientation sensors and permission to use them, and is not available on every device.

Does AR overlay stars on my camera?

Currently, AR renders a sky that follows your device’s orientation. It does not overlay a live camera image. Sensors and nearby magnetic interference can affect the heading; drag the sky to correct it.

How accurate is the simulation?

The simulation uses astronomical data and approximate calculations. Some details are simplified, and it is not intended for research, navigation or other precision-critical use. Visuals may differ from what you see with the naked eye.

Take a small detour into space.

You do not have to go far to find a sky you have never seen.