How To Turn Your Computer into a Universe Simulator

By Matthew Braga

Any old laptop or desktop computer is a pretty good stand-in for a clear night sky--we show you how.

Unless you live in a major metropolitan area, you may live in a city without the good fortune to be graced with a local planetarium. And not just the modernized digital planetariums we wrote about last month, but any planetarium at all. Save for driving beyond the city limits, past light pollution's reach, you'll be hard pressed to get your starry skied fix by just standing outside your home, waving a phone running Google Sky Map up in the air.

In fact, you'll probably fare better if you stay inside instead. Turns out that any old laptop or desktop computer is a pretty good stand-in for a clear night sky – provided you have the necessary software (and modest hardware) required to recreate the experience from within the comfort of your own home. It's like having a miniature planetarium on your couch or desk – but, you know, at a fraction of the size. We explore four programs that turn your home office or living room into a personal stellar cartography lab.

The Hayden Planetarium's Digital Universe Atlas

The American Museum of Natural History has played a big role in the development of the modern planetarium. One of the earliest applications for use in big digital domes – a piece of software called Partiview – was developed at the museum's Hayden Planetarium in 2000 to interpret its vast collection of astronomical data, as well as research from the wider scientific community. But this isn't just an in-house tool. You can actually download Partiview, along with a huge collection of the museum's astronomical models, as part of the Hayden Planetarium's Digital Universe Atlas.

It's easy to think of Partiview as a universe simulator at first glance. You can fly through space surrounded by a massive catalog of stars, planets, galaxies and nebulae, with textures and high-resolution imagery to match. But really, the more correct term is "visualization environment." Partiview is actually just a rendering engine that interprets sets of data – say, infrared imagery from the Hubble Space Telescope, or the position of galaxies within the Milky Way – which are then plotted and displayed on-screen. If it makes things easier, imagine you're exploring the data points of massive spreadsheet rendered in three-dimensional space. This makes it easy for scientists to add to, distribute and update data sets, and even render them in other applications.

The Digital Universe Atlas is regularly updated with new stars, orbits and planetary bodies, giving you access to some of the same data used by the scientific community – including much of the data you see used in many live planetarium shows. Much of this data comes from common catalogs, shared by the other applications listed here. For example, the location of many nearby stars came from the European Space Agency's Hipparcos satellite in the early 1990s, while the Sloan Digital Sky Survey has been conducting thorough studies of the Milky Way for over a decade.

You can download the Digital Universe Atlas for Mac, Windows or Linux PCs. But be warned: Partiview boasts the most downright archaic and terrifying user interface we've seen this side of 1996. Thankfully, all those mouse and keyboard shortcuts are relatively easy to get the hang of – thanks to the museum's extensive and well-written documentation – but don't expect your Xbox controller to get any love here.

Worldwide Telescope

While the Digital Universe Atlas is great at giving amateur astronomers access to a vast array of current scientific research, it's raw data approach can be rather daunting at first. If you're looking for a more friendly starting point, however, it's worth giving Microsoft Research's WorldWide Telescope a try.

As you can probably guess, Worldwide Telescope brings together "imagery from the world’s best ground- and space-based telescopes for the exploration of the universe" according to Microsoft's website. That means everything from the remnants of thousand-year old supernovas to the dispersal of cosmic dust are yours to zoom, pan and explore, stitched together in a "seamless, high-resolution panorama of the night sky." It's an experience not all that different from using Google – excuse me, Bing – Maps, except on a scale that's terapixels in size.

Much like the Digital Universe Atlas, you'll have access to celestial data from the Hubble Space Telescope and the Sloan Digital Sky Survey (SDSS), amongst other sources available online. There are even guided tours, prepared by respected scientists and researchers, of some of the more interesting galaxies and stars. However, what you won't see is this data visualized in Partiview-style 3D space. WorldWide Telescope's primary strength is in rendering imagery gleamed from observatory-based and orbiting telescopes.

That's not to say there's no 3D component at all, however. Major planets can be viewed in 3D – with high-resolution textures mapped to the surface – and their orbits can be tracked in real-time.

But if there's one thing Worldwide Telescope really has going for it, it's that you can try it out right now. If you're on a Mac or PC with Silverlight installed and an HTML5-capable browser, Microsoft offers a web client with some – but not all – of Worldwide Telescope's coolest features (sadly missing online is the 3D view). Your mileage may vary, of course – the web client ran slowly for us in Chrome on OS X, but worked fine in Safari.

However, though it's easy to get started with the web client, there's one big advantage of using WorldWide Telescope's desktop client on a Windows PC – it's the only application listed here that can be controlled using an Xbox controller out of the box, which makes it the easiest and most accessible of the bunch for anyone to pickup and explore.


Both WorldWide Telescope and the Digital Universe Atlas have their pros and cons, but if neither quite satisfies your itch for amateur home astronomy, it may be worth giving Celestia a try. Like Partiview, this is another visualization environment for astronomical data available for Windows, OS X and Linux – albeit, one with an interface that's considerably easier to use. This makes Celestia a good starting point for those who enjoy the relative simplicity of Microsoft's WorldWide Telescope, but still want to explore the universe in three-dimensional space.

Celestia is based primarily around the Hipparcos catalog of stars, and includes the usual complement of planets, moons and even spacecraft. However, it's real strength is in the extensive catalog of add-ons – including high-resolution textures, orbits for additional satellites and celestial bodies, and even accurate recreations of the fictional universes from Star Trek and Star Wars.

Thankfully, you don't have to go hunting for some of these more notable objects on your own. Similar to WorldWide Telescope, Celestia provides a handy library for finding points of interest as they appear in real-time – or any position in time, really – which can be useful for studying the locations of planets, stars or spacecraft during important astronomical events (such as, say, eclipses).

Universe Sandbox

Unlike most of the other applications here, Universe Sandbox focuses less on the breadth and wealth of its data, but on how that data can be displayed – and, perhaps more importantly, manipulated. It's by far the easiest of the applications listed here to use, and its availability on Steam might give you some indication of its target demographic – this is a scientific simulation that actually plays like a game, and it's just the sort of thing I'd feel comfortable putting into the hands of a few kids.

The developer categorizes the app as more of an "interactive space simulator" for Windows PCs, rather than, say, the academic visualization approach you'll find in the other applications mentioned here. But that's arguably also one of its strengths. Universe Sandbox is, at its core, a gravity simulator, and definitely the best looking the bunch. There are a variety of scenarios that depict, say, standard planetary orbits around the sun, or the movements of Saturn's moons, and you have the ability to modify such features as gravitational strength or mass in real-time. Not only is it easy to wreak havoc through a well-placed black hole, but insanely fun at the same time. You might even learn a thing or two about physics along the way.

Universe Sandbox also incorporates star data from the Hipparcos Catalog, in addition to the velocities and starting positions of moons, planets and asteroids, as gathered by NASA JPL's Horizon System. Best of all, there's a basic version available for free, which should give you a pretty solid idea of how things work. But if you want to go beyond the provided scenarios and take full control, it's well worth giving the paid version a try. There's nothing quite like creating your own simulations full of exploding moons and binary galaxies where the forces of gravity don't quite behave as you'd expect.