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What Is the SKA?

The first phase of the Square Kilometre Array at night.

Artist’s impression representing the first phase of the Square Kilometre Array at night, with its two instruments SKA1 LOW (in Australia, on the left) and SKA1 MID (in South Africa, on the right). SKA1 LOW will comprise 130,000 dipole antennas while SKA1 MID will comprise 200 dishes, including 64 MeerKAT dishes. Credit: SKA Organisation

By Willem van Straten

The Square Kilometre Array is an unprecedented international collaboration to build the world's largest radio telescope and address some of the most fundamental questions of modern science.

The full text of this article can be purchased from Informit.

When it comes to radio waves, most of us first think about the various devices that we use for communication, such as the radios in our cars and the phones in our pockets. However, there are many natural sources of radio emission, and as soon as we stop listening to ourselves we discover a universe full of signals from some of the most extraordinary places.

Our Sun is the brightest object in the radio sky. Its solar flares release enormous amounts of energy and produce crackling radio noise that can be detected easily with a small antenna.

Neutron stars are the collapsed remnants of once-bright stars. They are often visible only by their radio emissions, which sweep past the Earth like a lighthouse beam with each rotation of the star.

Supermassive black holes at the hearts of distant galaxies accelerate jets of material to almost the speed of light. This produces relativistic electrons that emit radio waves as they spiral around the embedded magnetic field.

Hydrogen, the most abundant element in the universe, can spontaneously emit a photon with a well-defined radio wavelength near 21 cm.

Finally, at the current limit of observable reality, the hot fireball that was our universe shortly after the Big Bang is visible today as a faint radio afterglow known as the cosmic microwave background.

To receive signals from the most...

The full text of this article can be purchased from Informit.