You are now the proud owner of Star In A Box.

Inside this box you can animate the different stages in a star's life and see how its brightness, size, and mass change with time.

Once you've opened the box just click the play button to start animating.

You don't appear to have Javascript enabled so you won't be able to use the interactive features of Star In A Box. However, you can still download data to make your own investigations of how the brightness, size and mass of stars change as they go through their lives:


Star in a Box allows you to explore one of the most enigmatic tools in astronomy - the Hertzsprung-Russell diagram.

When you first open the box you start with a star with the same mass as the Sun but you can change this to a different mass at any time. The tracks that you see on the graph (on the left) map the lifecycle of the star. You can play the animation of the star moving around the diagram, and see how its brightness, size, surface temperature, and mass change in the panels on the right.

Stars can take billions of years to go through their lives with the dramatic events taking place in relatively short periods of time. In the animation we speed up time when the star is not really changing much and slow things down for the dramatic phases of the star's life.


  • space Play/pause the animation
  • Move the animation forwards/backwards in time
  • L Opens/closes lid
  • M toggle between basic and advanced modes


Design & Development: Jon Yardley, Stuart Lowe, Edward Gomez, Haley Gomez & Chris North

Supported by LCOGT & Cardiff University

Based on the stellar evolution work of Jarrod Hurley, Onno Pols, and Christopher Tout

0 Myrs
Caution: Supernova Imminent