public alpha now available



General Questions

What is Universe Sandbox?

At its core, Universe Sandbox is a gravity simulator (that very intentionally happens to be fun and easy to use).
Check out the "what is it?" page for more info.

What is Universe Sandbox ²?

Universe Sandbox ² is a complete rewrite of the original and has been in development since fall 2011.
Purchase the Alpha and read more about it here.

Or check out our Universe Sandbox ² FAQ.


What does it look like?

Check out the video preview, user videos, or view screenshots of the program in action.

What's the difference between the free and premium versions?

The free version of Universe Sandbox lets you explore and discover any of the included simulations for as long as you want. The premium version lets you create your own simulations, add new bodies (like planets and stars), and change all the various simulation properties.

View a comparison chart | Free vs Premium

What is Universe Sandbox for?

  • Learning about the universe in which we live (without realizing that you're learning).
  • Exploring how gravity works, one of the four fundamental forces of our universe.
  • Having fun with creation and destruction on an epic scale.
  • Creating realistic imagery and movies of our universe.
  • Making cool stuff to look at.

How much does it cost?

Universe Sandbox is free to use forever for viewing and exploring simulations. Buy the premium version for $9.95 USD to unlock all the features. See the Buy page for details.

How do I use it?

There's an introductory tutorial and step-by-step activities built into the program. No worries... You don't have to be a rocket scientist.

What simulations are included?

Universe Sandbox includes 70+ systems, both real and fictional.

  • Includes the 8 planets of our solar system, 5 minor planets, 160+ moons, and hundreds of asteroids.
  • Gamma Ray Burst locations
  • Andromeda & Milky Way galaxy collision
  • Shoemaker Levy 9 collision with Jupiter
  • Recently discovered comet with retrograde orbit - 2008 KV42
  • Rho Cancri Solar System (55 Cancri) - a star with 5 known planets
  • The 100 largest bodies in our Solar System
  • Comparison of the largest known stars
  • Pioneer & Voyager encounters with Jupiter, Saturn, Uranus, & Neptune
  • Lagrange points of the Earth & Moon
  • Moons coalescing into a single planet
  • Asteroid Apophis passing near Earth in 2029
  • Nearest 1000 stars to our Sun
  • Nearest 70 Galaxies to the Milky Way


What are the core features?

  • Full-featured interactive n-body gravity simulator.
  • Everything is measured in real units: kilograms, meters, seconds.
  • 3D Mode for use with red & cyan glasses (anaglyph stereoscopic)
  • Support for 3D DLP televisions
  • Complete introduction and included tutorial.
  • Includes 10 step-by-step activities that explain the various controls.
  • Editable simulation files let you create an unlimited number of scenarios.
  • Full control of the speed of time.
  • Full control of gravity.
  • Multiple color modes to visualize speeds and accelerations.
  • Two collision modes
    • Bounce: A fun, fictional mode where bodies bounce off of each other like big rubber balls.
    • Combine: A more realistic mode where bodies combine into a single body when they collide.
  • Rings systems
    • Rings are simulated as hundreds of particles and are effected by gravity.
    • Includes scale ring systems of Saturn, Jupiter, Uranus, and Neptune.
    • Generate rings around bodies with a single click.
  • Particle grids
    • Easily create 2D or 3D particle grids and then warp them with Jupiter- sized planets.
  • Galaxy Collisions
    • Watch galaxies rip each other apart.
  • Full sky panoramic view of the Milky Way
  • Easy-to-use interface that's fully controllable with the mouse.
    • Lots of additional keyboard shortcuts
    • Laptop-friendly controls
  • Capture high-resolution screenshots
    • Combines multiple screen captures into a super high-resolution image; 50+ megapixel shots are possible.
    • Tools to capture image sequences
  • Easy Updates
    • Automatically checks for updates so you'll always have the latest version.


What's in the latest version?

Check out What's New for a detailed breakdown.


Universe Sandbox

What are all the keyboard shortcuts?

There's a complete list on the command reference page.

How do I use Universe Sandbox with 3D glasses?

  1. Start Universe Sandbox and open a simulation.
  2. Click on the ‘Show View Controls’ bar on the far left side of the window.
  3. Scroll down to ‘Screen Options’, if needed.
  4. Check the 3D checkbox to enable 3D mode.
    Note: The 3D Mode should be set to Anaglyph (and not Cross Eye or DLP).
  5. Close the View Controls if you like.
  6. Put on your 3D glasses making sure that your left eye is looking through the red lens.
  7. Allow your eyes to relax. It can take a few minutes to get accustomed to the effect.
  • Optional step: Change the Color Mode to Monochrome. (This can make the 3D easier to see.)

How do I switch to full screen?

  • Press Alt-Enter
  • Click the 'Switch to Full Screen' button in Settings.


How do I zoom when I don't have a mouse wheel?
(I have a laptop)

  • Use the keys W & S to zoom in and out.
  • If you have problems with zooming, try turning off scroll wheel support in Options from the main menu.


How do I easily reload a simulation?

  • Press Ctrl+R to reload/restart your current simulation.

Simulation Questions

Why does Mercury get thrown out of the Solar System when I turn up the time step?

  • As you turn up the time step you lower the accuracy of the simulation. If the accuracy is too low, bodies will get thrown out of the system.
  • The numbers: Mercury takes about 88 days to make a single orbit around the sun. A time step of 22 days would only be calculating a new position for Mercury 4 times in that period. This isn't enough accuracy to maintain a stable orbit. The Earth is further out and takes 365 days to orbit the sun. This same time step of 22 days results in about 16 position calculations for the Earth which is enough to maintain an orbit.


Why don't you include any moons in the system 'Our Solar System'?

  • Since some moons make full orbits of their respective planets in less than 1 day, the maximum speed (or time step) that you can run the system is much lower than without them. (See the question above for more info on time steps.)
  • Load the system 'Our Solar System - all known moons' to see all the 160+ moons in our Solar System.


I made a black hole but everything just got flung into space. Why didn't they get sucked in?

  • Your time step is too high for a body with such a large mass.
  • Press the A key or the numpad Enter key to turn on auto time step before you create the black hole.
  • Auto time step adjusts the time step to maintain a reasonably accurate simulation.


Is there any difference between a black hole and any other body in Universe Sandbox?

  • No. For the purposes of the simulation, a 'preset' black hole in Universe Sandbox is equal in mass to 100 of our Suns. Real black holes can be larger or smaller than this.


What's the math behind all of this?


How accurate is Universe Sandbox?

Solar System-sized simulations at a small time step (~2 minutes/second) are very accurate.

Galaxy sized simulations are only representative and not very accurate. Universe Sandbox doesn't take dark matter into account, which doesn't have much of an observable effect on our solar system but noticeably affects galaxies. Nor does Universe Sandbox consider Einstein's theory of general relativity as the basis of any of its calculations.


Where did you get your data?

Data used in Universe Sandbox was collected from a variety of sources:

JPL's Horizon System - Planet, moon, and asteroid starting positions & velocities

Star Positions & Velocities - David Nash

Star Color Values- Mitchell Charity

Atlas of the Universe - Richard Powell


Legal Questions

Can I upload a video of Universe Sandbox to YouTube and monetize it?

Yes. Uploading and monetizing videos of any verison of Universe Sandbox (1 or 2) is fine by us. Please follow the rules in the next question (provide attribution with a link)...


Can I use Universe Sandbox to create screenshots & movies for use in other products?

Yes. Here are the simple rules:


  • Any use of images or videos created with Universe Sandbox requires attribution - "Created with Universe Sandbox" or "Universe Sandbox".
  • Ideally attribution will be on screen at the same time as video or image is shown but a listing on a title screen or prominent listing in the credits is also acceptable. If published on the web, the video or screenshots must include a clickable link to: (like in the YouTube description).
  • Do not attribute in a way that suggests our endorsement of you or your product.
  • And ideally please send a link to us where we can see what you've done.


Other Applications

Are there other programs like Universe Sandbox?

TestTubeGames' Gravity Simulator

  • Fling Planets or redefine the forumal for gravity in this easy to use 2D simuatlor.

Pixel Gravity

  • Gravity simulator with both a free trial and full version for Windows PCs.
  • Extremely impressive feature list and comprehensive simulator.

Gravity Simulator

  • An n-body simulator similar in concept to Universe Sandbox and capable of scale simulations of our Solar System.
  • Using the rotating frame feature, you can easily study the complex orbital relationship between the various moons of Saturn, or the relationship between Earth's orbit and the horseshoe orbit of 3753 Cruithne, an asteroid often referred to as "Earth's 2nd moon".
  • It also includes some advanced features for recording data that can be graphed in a spreadsheet app.
  • Gravity Simulator is for Windows PCs.


  • A gravity simulator available for both Mac and Windows as a 15 day trial.
  • Uses Newton's Law of Gravitation to run scale simulations of our Solar System.




  • Free, realistic space flight and gravity simulation program for Windows PCs.
  • Explore the solar system in realistic and fictional spacecraft.

Kerbal Space Program

  • Build your own rockets, launch them, crash them, land on the moon.
  • Not a full gravity simulator as only one planet or moon acts on the spacecraft at a time, but still really great.


Are there other physics sandboxes?


  • Physics based 2D sandbox (for things here on Earth).
  • Commercial software for Windows and Mac OS X.

Garry's Mod

  • Physics based 3D sandbox (for human sized objects).
  • It's a game Windows and Mac.


  • A simple gravity simulator that's more aestetic than representative of reality.
  • Runs under Linux, Windows and Mac OS X.


What are some astronomy apps that don't simulate gravity?


  • A space simulator that lets you explore our universe in three dimensions (but it's not interactive and doesn't simulate gravity).
  • All movement in Celestia is seamless and you can zoom from the Earth to the edge of our Galaxy.
  • Celestia runs on Windows, Linux, and Mac.


  • From the creator of Celestia, is an easy to use and beautiful solar system visualization tool for Mac only.

Eyes on the Solar System

  • Our solar system and NASA mission data.
  • Runs in a browser.
  • Created by JPL & NASA.

Digital Universe

  • A free program from Hayden Planetarium for Windows, Mac, Linux, and IRIX.
  • Includes data on thousands of stars and galaxies.
  • This is not a gravity simulator, only a viewer.

Space Engine

  • Free simulator with both real and procedural content allowing unlimited exploration of our galaxy.


  • 3D space simulation with lots of great visuals.


  • Free planetarium for you computer (not a gravity simulator).
  • Runs under Linux, Windows and Mac OS X.

Explore the Solar System

  • Solar system 3D exploration tool developed in the Unreal 3D engine.


  • Tools for creating sci-fi space maps.

What about electrostatic simulations?

I know of nothing as full featured as Universe Sandbox, but a user sent me links to these:

Electrostatic Fields Applet

  • Free and easy to use.

Electrostatics 3D

  • Expensive and designed for education specifically.


And atom visualizations?

Atomic Dashboard

  • Chemistry resouce and visualization tool.
  • Mac only.

Atom in a Box

  • Easy to use visualization tool for iOS (iPhone & iPad).

Download & Installation

How do I Install Universe Sandbox?

  1. Click on the install button to download the file 'universe-sandbox-setup.exe'.
  2. Run the 'universe-sandbox-setup.exe' installer.
  3. Follow the simple steps in the Setup Wizard to complete the installation.
  4. Once installed, Universe Sandbox will automatically run.

How do I run Universe Sandbox?

  • Universe Sandbox will run automatically after installation.
  • After it's installed, find it in your Start Menu and on your desktop.
  • If you're running Windows 7 you can pin it to your taskbar.

How do I get updates?

  • Every time you run Universe Sandbox it will check for updates. If an update is found it will ask if you want to get it. You'll always have the latest version.

Why is it trying to connect to the internet?

  • When you run Universe Sandbox it connects to to check for updates (which forwards to where the installation files are hosted).
    I give you my word it's not doing anything malicious.

How do I uninstall Universe Sandbox?

  1. Click on the Windows Start button.
  2. Open the Control Panel.
  3. Open Add or Remove Programs.
  4. Select Universe Sandbox in the list and then click the Remove button.

Universe Sandbox crashes when I try to run it.
How do I fix this?

Can I distribute Universe Sandbox?

  • Since updates are released frequently, it would be best if you didn't. Please just link people to this website so that people will always be downloading the latest version available.
  • If you insist on distributing this application you must use one of the unaltered setup files available from this website. You are not allowed to repackage the program.

Will this work on a Mac?

  • Universe Sandbox will run on Macs in a virtual environment (like Parallels Desktop).



Version 1 Info

Can I download Universe Sandbox 1?

Where is Universe Sandbox 1 installed?

  • On XP: %userprofile%\Local Settings\Apps
    (e.g. C:\Documents & Settings\Dan\Local Settings\Apps)
  • On VISTA: %userprofile%\AppData\Local\Apps
    (e.g. C:\users\Dan\AppData\Local\Apps)

When I try to update to the latest version I get this error: "Access to the path '1.0.???.?\dxdx9_31.dll' is denied.

  • This error occurs under Vista when you try to update.
  • You need to run Universe Sandbox with administrative privileges for updates to complete successfully.




How much does Universe Sandbox cost?

Individuals, Teachers, Schools, & Non-Profits

  • A single product key for Universe Sandbox is $9.95 USD.
  • Universe Sandbox is free for schools anywhere in the world. Learn more.

Commercial & For-Profit

  • A special license is required for using images or video created with Universe Sandbox. Please contact sales to inquire about a commercial license.

Do I need a special license to use screenshots and video generated with Universe Sandbox for commercial purposes?

  • Yes. Please contact sales to inquire about a commercial license.
  • Using video or images for non-commercial or educational use is encouraged and doesn't require a license. Please credit Universe Sandbox and include a link back to

What happens when the trial is over?

  • Universe Sandbox reverts to the free-forever system viewer.
  • You can continue to open and view systems, but you can no longer interact with them.
  • You'll no longer be able to control gravity, add new bodies, or change properties.
  • Just buy a product key to restore all the interactive features.


Universe Sandbox ²

What is Universe Sandbox ²?

Universe Sandbox ² is a complete rewrite of the original and has been in development since fall 2011.

It is no longer a one-person project; the new team has added a dedicated physics programmer, astronomer, climate scientist, graphics programmer, and code architect to bring all of the pieces together.

When will it be available? Where can I get it?

The public alpha is available now for PC, Mac, and Linux.

Get instant access to the Universe Sandbox ² Alpha on Steam and pre-order the finished game: Buy Universe Sandbox ²

If I buy the alpha version now do I have to buy Universe Sandbox ² again when the final version is released?

No, a single purchase gives you instant access to the alpha plus free updates through Steam as we continue development. This includes the final release of Universe Sandbox ².

What does "alpha" mean?

Universe Sandbox ² is still alpha software. We're not done fixing many of the issues and improving it. There remain many bugs, and you, the early access user, will help us uncover even more. Buying-in early means you won't have to wait to explore the many new and exciting features that are already in place. But know that all of the final polish won't be there yet.

What platforms does Universe Sandbox ² run on?

Windows, Mac, and Linux/Steam OS.

Will there be a mobile version for iOS/Android?

Maybe. If we decide to release a mobile version, we won't begin porting until after the initial release for PC, Mac, and Linux.

Wasn't the new version going to be called Universe Sandbox 3?

It was going to be called Universe Sandbox 3, but we've decided it will be less confusing for most users to call it Universe Sandbox ².


In 2008 Dan, the creator of the original version, released Universe Sandbox v1.0 and in 2010 he released Universe Sandbox v2.0. One year later, v2.1 was released on Steam and while the internal version number remained, the 2 was dropped from the title of the game. Given that most people are unaware of the internal version numbers and that 99% of all copies ever sold were sold on Steam as Universe Sandbox, most will assume the sequel will be called Universe Sandbox ².


Thanks for being dedicated fans who are paying enough attention to realize the inconsistency here. Hopefully everything is now clear.

What new features are in Universe Sandbox ²?

Some of the new features include:

  • Climate simulation
  • Improved collisions
  • Stellar evolution and supernovae
  • Animated star surfaces and solar flares
  • Light-warping black holes
  • Dark matter
  • Procedural surfaces and planets

Read more about what's new in Universe Sandbox ².

If I bought Universe Sandbox will I receive Universe Sandbox ² for free?

Unfortunately, no. Universe Sandbox ² is not just an upgrade, it's a completely new product. You can read more about why in this post.

Does Universe Sandbox ² support multi-core processing?


How about a 64-bit version?

Yes. We plan to release a 64-bit version for all platforms.

What are the system requirements?

These are the preliminary minimum requirements for running Universe Sandbox ²:
  • Graphics:
    • DirectX9.0c (Windows) or OpenGL (Max, Linux)
    • 512MB Video Memory
    • Shader Model 3.0
  • System:
    • 1.6GHz dual core
    • 1GB RAM
    • 1GB free disk space

Original Version

When was Universe Sandbox first released?

Universe Sandbox was original released in 2008 with a major update released in 2010.


Read the FAQ about the 2008 and 2010 versions.