Wonders of the Universe

FINDING ANDROMEDA

The connection between the history of the Serengeti and the science of light is a dimly glowing jewel in the velvet Tanzanian sky. With no cities to pollute the darkness, the plains of the African night are bathed in the light of a billion suns. The glowing arc of the Milky Way Galaxy dominates the sky, a silver mist of stars so numerous, they are impossible to count. Every single point of light and every patch of magnificent mist visible to the unaided human eye have as their origin a star in our own galaxy, or the misty clouds known as the Magellanic clouds – two small dwarf galaxies in orbit around the Milky Way. All except for one…

To find it, you first need to recognise the distinctive ‘W’ shape of the constellation of Cassiopeia. It sits on the opposite side of Polaris, the North Star, to the constellation Ursa Major, otherwise known as The Great Bear or The Plough. Cassiopeia, being so close to Polaris, is a constant feature in the northern skies – it simply rotates around the pole once every twenty-four hours and never sets below the horizon at high latitudes. If in your mind’s eye you put the ‘W’ of Cassiopeia upright, then just beneath the rightmost ‘V’ you will be able to see quite a large, faint, misty patch in the sky. It is comparable in brightness to most of the stars surrounding it, although dimmer than the bright stars of Cassiopeia. This unremarkable little patch is, in my view, the most intellectually stunning object you can see with the naked eye, because it is an entire galaxy beyond the Milky Way. It is called Andromeda, and is our nearest galactic neighbour. It is home to a trillion suns, over twice as many stars as our galaxy. It is roughly twenty-five million million million kilometres (fifteen million million million miles) away, and here is the connection.

This Homo habilis skull was found in the Olduvai Gorge in Tanzania and is believed to be around 1.8 million years old.

PASCAL GOETGHELUCK / SCIENCE PHOTO LIBRARY

Two and a half million years ago, when our distant relative Homo habilis was foraging for food across the Tanzanian savannah, a beam of light left the Andromeda Galaxy and began its journey across the Universe. As that light beam raced across space at the speed of light, generations of pre-humans and humans lived and died; whole species evolved and became extinct, until one member of that unbroken lineage, me, happened to gaze up into the sky below the constellation we call Cassiopeia and focus that beam of light onto his retina. A two-and-a-half-billion-year journey ends by creating an electrical impulse in a nerve fibre, triggering a cascade of wonder in a complex organ called the human brain that didn’t exist anywhere in the Universe when the journey began

AlltheSky.com

On autumn and winter evenings, the spiral galaxy M31 (Andromeda) is visible to the naked eye in northern skies. To locate it, you first need to identify Cassiopeia, and its distinctive ‘W’ shape. Using the point of the ‘V’ on the right-hand side as an arrow, look beneath it for a large misty patch in the sky.

NASA

Observing the night skies with the naked eye can only take us so far on our journey to discover and understand the wonders of our universe. Advances in technology have brought us crafts that can take humans on expeditions beyond our planet, but also sophisticated equipment that has changed our view of the Universe entirely.

The Hubble Space Telescope being repaired by an astronaut from Endeavour. This eleven-tonne telescope has allowed astronomers and scientists to see further into our universe than ever before.

NASA