The colour of our galaxy

We know a lot about our celestial neighbourhood. The galaxy in which our solar system resides has been the focus of many outstanding minds for many generations.

We know, for example, that we share the Milky Way with at least 200 billion other stars and their planets. We know that as a galaxy, the Milky Way is actually a giant, with its mass being somewhere between 750 billion and one trillion solar masses, and a diameter of around 100,000 light years. Almost ungraspable stats – but in a game of galactic top-trumps, undeniably hard to beat.

Yet despite a wealth of knowledge, we have never had a direct view of our galaxy from afar. As such there is still one apparently simple property that remains a mystery. Its colour.

Given the incredibly detailed understanding we have of the Milky Way, its colour might to some sound like a trivial detail – in fact astronomers can tell an awful lot from a celestial body’s hue. As such a team from the University of Pittsburgh set out to find this property. The challenge of course was in determining something that was hidden from us by virtue of our proximity within the subject of interest.

Jeffrey Newman, Pitt professor of Physics and Astronomy at the university decided that the best way to go about this wasn’t to look at our galaxy at all. He examined the colour of other galaxies similar to the Milky Way in properties that were able to be determined—specifically, their total amount of stars and the rate at which they are creating new stars. The Milky Way Galaxy, the Pitt researchers realised, should then fall somewhere within the range of colors of these matching objects.

After holding up what amounts to a galactic mirror to the face of the Milky Way, we now know that it has indeed been named correctly.

Having collated all suitable candidate galaxies Newman described the overall spectrum of light from the Milky Way as being very close to the “light seen when looking at spring snow in the early morning, shortly after dawn.” How wonderfully poetic.

After holding up what amounts to a galactic mirror to the face of the Milky Way, we now know that it has indeed been named correctly. The dusting of stars, planets, comets, asteroids, meteors and moons that we call home collectively produce a beauty that will forever be obscured from our direct gaze – to get the kind of vista that Newman has put together man would have to travel several thousand light years. That’s along flight for a good view, however spectacular it might be.

All of this insight would have been impossible without the computing power that has come to dominate much of modern research. Outstanding minds are no longer enough, modern science has become an amalgam of the insight of human brain power and the data donkeywork of powerful computing. And what a team they make – in this issue we look at the state of play of computing in science and look at some of its successes and future aspirations – from quantum computers to retinal implants, each challenging and each inspiring.