Ripples in spacetime, colliding black holes, the expansion of the Universe: often it’s the things we don’t understand that intrigue us the most. If astronomers are to have any hope of solving these mysteries, they need to build bigger telescopes.
One such telescope is the Square Kilometer Array (SKA), due to begin construction in 2020 with the first results expected in 2023. But this is a telescope with a difference. It will be made up of a number of different dishes, spread across two continents. The combined signal they receive effectively creates a single dish covering over one square kilometre of the sky. This is like two astronomers standing side by side, each with a telescope, combining their respective seeing powers to create one almighty instrument.
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SKA will observe the deepest regions of the Universe using a method called radio astronomy. In contrast to the optical light observed by ‘regular’ telescopes, radio astronomy uses huge dishes to detect radio signals beamed out by deep-sky objects like galaxies, stars and black holes. This is why the dishes are being constructed in remote corners of Western Australia and South Africa, as well as other areas of the African continent, to avoid nuisance artificial signals created by humans.
The Universe is a dusty place. Cosmic dust is everywhere; particularly in star-forming regions where the secrets of star birth and galaxy formation are waiting to be discovered. With radio telescopes, astronomers can peer through this dust and get a clearer view than they could with the human eye. And, because light from the birth of the Universe 13.8 billion years ago takes time to reach our planet, by looking deeper into space, astronomers hope to catch a glimpse of the moment the first stars ignited and spread light across the cosmos.
It is hoped that SKA will help unlock some of astronomy’s most enduring mysteries, such as the magnetic fields that surround planets (including our own), stars and galaxies, and the role these forces have played in the formation and evolution of the Universe. SKA will also look at the unknown force ‘dark energy’ (thought to be responsible for the accelerating expansion of the cosmos), as well as gravitational waves – the ripples in space-time generated when massive cosmic objects collide (see page 36). SKA will be able to detect gravitational waves produced by the collision of behemoth objects known as supermassive black holes, potentially opening up a new way for astronomers to observe the Universe.
Much has been learned since humanity first looked up at the night sky and pondered its own existence, but there is more to discover. How did the Big Bang occur, and what was the early Universe like? How do galaxies form? Why is the Universe expanding? Projects like SKA are another step towards making sense out of the cosmic unknown. Watch this space.
SKA in numbers
2 million – The number of years it would take to play back a day’s worth of SKA data on an iPod
2 – The number of times SKA’s optical fibre cables would wrap around the Earth
100 million – How many PCs you would need to match the processing power of SKA’s central computer
50 – The distance in lightyears from which SKA could detect an airport radar on another planet