Stellarium: Tom's Mac Software Pick

The Universe As Seen From Your Backyard

Stellarium planetarium app
Courtesy of

Stellarium is a free planetarium app for the Mac that produces a realistic view of the sky, just as if you were looking up from your backyard, with the naked eye, binoculars, or a telescope. And if you've ever wanted to view the sky from somewhere else on earth, say New Caledonia or Newfoundland, Stellarium can set your location to anywhere you like, and then display the sky with all of its stars, constellations, planets, comets, and satellites, just as if you were right there looking up.


  • Catalog of over 600,000 stars
  • Constellation illustrations (20+ cultures)
  • Full Messier catalog
  • Realistic Milky Way
  • Eclipse, shooting star, and supernova simulations
  • Telescope interface
  • Can add your own objects and landscapes to customize system


  • Search function can be finicky

Stellarium has been a favorite of ours for quite a while. It provides a rich catalog of objects, along with historical and astronomical information about each one. It can produce a remarkable nighttime sky that's so detailed you may think you're outside, lying on the lawn gazing skyward, with the Milky Way stretching out like a sparkling chain of lights across the sky.

Or at least, that's the way I remember it from my youth. Unfortunately, the nighttime sky isn't the same one I saw when I was young. Cities have grown rapidly, and the sky is full of light pollution that can make even the brilliance of the Milky Way seem pale, or in the worst of locations, non-existent.

But Stellarium can reproduce the dark skies of old, even if you're located in the middle of a big city, and haven't seen any but the brightest of stars in recent memory.

Using Stellarium

You can run Stellarium as a windowed or full-screen app. By default, it takes over your full screen, and that's really the way Stellarium should be used, for the full effect of watching the nighttime sky.

Stellarium uses your Mac’s location information to produce a sky that should be the same as the one outside your window, only better. But Stellarium only has so many built-in predefined locations. While it does its best to guess where you are, and match it up to a nearby location, you can improve its accuracy by entering your longitude and latitude into the location screen. If you don’t know the longitude and latitude, you can use just about any of the online maps to look up your location and find the proper coordinates.

Once you enter your coordinates, Stellarium will produce a very accurate map of the skies for your area. You can select the time and date to be displayed, letting you view tonight’s sky, or go back in time to see the skies as they were, or forward in time to see how they will be.

Stellarium doesn't display a static view of the sky; instead, the view of the sky is dynamic, and changes as time rolls on. By default, Stellarium's internal timepiece runs at the same rate as local time, but you can speed time up if you wish, and watch an entire nighttime of viewing flash by in a few minutes or hours.

Stellarium UI

Stellarium has two main controls: a vertical bar that contains configuration settings, such as location, time and date, search, and help information. The second bar runs horizontally along the bottom of the screen, and has the controls for the current display, including options for displaying constellation information, the type of grid to use (equatorial or azimuthal), and background displays, such as landscape, atmosphere, and cardinal points. You can also choose to display deep sky objects, satellites, and planets. There are additional viewing options available, and you can control how fast or slow time plays out on the sky display.

Overall, the UI, which appears and disappears as needed, is easy to use, and just as important, gets out of the way when you're viewing the main display.

Stellarium Options

Stellarium has a large developer community that maintains the open source app. As a result, there are a number of optional capabilities that can be added to Stellarium, including the ability to use Stellarium as a guide for your smart telescope, or as the control for a planetarium display. I haven't found an inexpensive way to build my own planetarium in our home yet, but if I did, Stellarium would be the heart of the system.

If you would like to view the nighttime sky, even on cold, rainy, or overcast nights, Stellarium may be just the planetarium software for you. It's also a great app for learning about the nighttime sky, whether you're young, old, or in-between.

Stellarium is free.

See other software choices from Tom's Mac Software Picks.

Published: 3/14/2015

Updated: 3/15/2015