What is the Square Kilometre Array?

The Square Kilometre Array (SKA) will be the world’s largest and most sensitive radio telescope. It will comprise thousands of radio wave receptors (antennas) some of which will extend out to distances of 3,000 km from their central core region.

What will the SKA do?

The SKA will see back to a time before the first stars lit up. Optical telescopes see the light from stars. Before stars existed there was only gas; a radio telescope with the sensitivity of the SKA can see back in time to the gas that existed before stars were even born.

The SKA will address a wide range of fundamental questions in physics, astrophysics, cosmology and astrobiology. It will be able to investigate previously unexplored parts of the distant Universe.

Who is building the SKA?

The SKA Organisation, based in Manchester in the UK, is leading the international project to build the SKA. See here for more information on the member countries of the SKA Organisation.

How will the SKA antennas be arranged?

The SKA will be built in Australia and in Southern Africa. There will be 3 000 dish antennas, each about 15 m in diameter as well as two other types of radio wave receptor, know as aperture array antennas. The antennas will be arranged in five spiral arms and the dishes in Southern Africa will extend to distances of at least 3 000 km from the centre of the core region.

What is radio astronomy?

Astronomers use radio telescopes to explore the Universe by detecting electromagnetic radiation emitted by objects in space. The electromagnetic spectrum describes how photons, or little bundles of energy, travel in waves.

How is radio astronomy different to optical astronomy?

Radio telescopes detect radio waves and optical telescopes detect light waves. Radio waves have a different frequency to light waves – they occur in a different part of the electromagnetic spectrum. Radio telescopes provide alternative views of the Universe than those seen with an optical telescope; they can reveal invisible gas and areas of space that may be obscured with cosmic dust.

What is interferometry?

Radio telescopes can be used individually or they can be linked together to create a larger virtual telescope known as an interferometer. The SKA will be the world’s largest interferometer.

What is the difference between the SKA and today’s radio telescopes?

Covering frequencies of 70 MHz – 10 GHz, it will make a revolutionary break with today’s radio telescopes. It will:

• Have a collecting area of almost one million square metres, giving it 50 times the sensitivity other telescopes;
• Survey the sky 10,000 times faster than other telescopes;
• Integrate computing hardware and software on a massive scale, in a way that best captures the benefits of these exponentially developing technologies. To give you an idea of scale, the SKA precursor telescopes on each candidate site (ASKAP and MeerKAT) are each about 2-3% of the full SKA.