Milky Way is the colour of 'spring snow after sunrise'

THE colour of the Milky Way is like "spring snow an hour after sunrise", according to new research carried out by astronomers. Scientists have been trying to determine the exact colour of the Earth's galaxy to work out the age of its stars and how quickly they are being formed, reports the BBC.

But obtaining the "bigger picture" has been hindered by the fact that astronomers can only see from inside the galaxy with their view blocked by dust. While the Milky Way is around 100,000 light years in breadth, it is only possible to see up to 2,000 light years in any direction.

"The problem is similar to determining the overall colour of the Earth, when you're only able to tell what Pennsylvania looks like," said Jeffrey Newman, professor of physics and astronomy at the University of Pittsburgh.

Prof Newman and his student Tim Licquia have therefore studied data from the Sloan Digital Sky Survey, a collection of colour images of nearly one million galaxies.

By comparing galaxies with similar masses and rate of star formation, they were able to produce a precise colour of the Milky Way. It was, reassuringly, white. But not just any white.

“The best description I can give would be that if you looked at new spring snow, which has a fine grain size, about an hour after dawn or an hour before sunset, you’d see the same spectrum of light that an alien astronomer in another galaxy would see looking at the Milky Way,” said Prof Newman.

It is somewhere between that of an old-fashioned incandescent lightbulb and noon-time sunlight, which suggests that the rate of star formation has been declining over time.

The research was presented on Wednesday at the American Astronomical Society meeting in Austin, Texas. ·