Two space telescopes working together have taken a spectacular new photo of our nearest galaxy lit up like a neon sign. The Andromeda Galaxy, also known as Messier 31, is a twin of our own Milky Way, and a whirlpool of hundreds of billions of stars.
It is like a Catherine wheel firework tilted away from us. Though our closest neighbour, this spiral star city lies 2.5 million light-years away, so that we see it as it was before Mankind’s earliest ancestors appeared on Earth.
The orangey-red rings are cooler regions od dust and gas where new stars are being born and which Europe’s heat-seeking telescope Herschel observed through its infrared eyes.
Superimposed are bright blue glows marking violent spots where stars are dying, black holes forming and pairs of stars are locked in gravitational battles to survive.
The blue picture was taken with another space observatory, XMM-Newton, which watches the cosmos with X-ray vision. Both images, released as a composite by the European Space Agency, were taken over Christmas. They were first shown last night on Professor Brian Cox’s hit BBC show Stargazing Live.
The view would be impossible from Earth because both X-rays and infrared radiation from space is absorbed by our own atmosphere.
But it is visible in normal light on dark nights as the furthest object visible with the naked eye. It appears as just a faint fuzzy glow but binoculars or a small telescope will show that it extends across an area of sky much larger than the apparent size of the Moon.
The Andromeda Galaxy, part of our Local Group of galaxies, is actually on a collision course with our own Milky Way – but luckily not for around 4 billion years! From outside, that event could resemble this merger of two spiral galaxies! Despite the great distance, there have been suggestions that a planet has been detected orbiting a star in the Andromeda Galaxy.
