Everything you see when you look up at the night sky emits visible light. But like an orchestra, if you only tune in to the sound from the violin, then you are missing the greatest portion of the music. To fully appreciate the orchestra's true magnificence you must listen to all the instruments.
The same goes for the night sky; we must look at all of the radiation being emitted from objects to truly fully understand their nature and unravel their deepest secrets.
Visible light makes up just a tiny portion of the electromagnetic spectrum (ES). Beyond the violet end of visible light are ultraviolet light, X-rays and gamma-rays. Extending beyond the red end of visible light are infrared, microwaves and radio waves.
Differentiating them all is a property called "wavelength" with gamma-rays being the shortest (a wavelength of 10-12 meters) and the longest being radio waves (a wavelength of tens of kilometers).
The real challenge for astronomers, though, is the somewhat useful life-preserving blanket around the Earth. Our atmosphere may keep the majority of ionizing space radiation out, but it also hinders astronomers' ability to see the full ES.
In order to see the blocked radiation, astronomers launch telescopes into space. Fortunately, visible light, some of the 'near' infrared and radio waves make it through to the surface, making astronomical observations possible.
One international program is making use of the ability to observe radio frequencies from Earth and it is setting up the world's largest radio telescope.
The Square Kilometer Array, or SKA, will be composed of several thousand 15 meter dishes spread out across a continent.
Jo Bowler, Outreach Officer for SKA, told Discovery News, "The SKA will be the world's largest interferometer which means it will correlate signals from thousands of linked 15 meter dishes and aperture array antennas to create a collecting area equivalent to a radio telescope with a 1 square kilometer dish."
Bowler explains that "it would be impractical to build such a large single dish. The huge collecting area of the SKA will provide greater sensitivity than smaller dishes can offer and the multiple stations of antennas will be spaced along spiral arms reaching more than 3,000 kilometers from the core region. It will provide very high resolution images."
The project, which will cost 1.5 billion Euros ($2.2 billion), will either be built in South Africa or Australia/New Zealand with the final decision being made in 2012.
Unfortunately we will have to wait until 2024 before the instrument is fully operational. Until then, there is lots of work for the 70 organizations from 20 different countries that are working on its development, with the UK playing a major role in coordinating activities from Jodrell Bank, home of the great Lovell Radio Telescope.
Once it is commissioned, SKA will address some of the great unanswered questions in astrophysics today:
1. It will map the cosmic distribution of hydrogen which will help understand the mysterious dark energy supposedly driving the expansion of the Universe.
2. The search for extraterrestrial intelligence is always high on the agenda for radio telescope installations and the SKA will be able to look for the weakest ET signals and search for evidence of complex molecules, the building blocks of life.
3. It will try and look back to a time before the first stars turned on and see where the first stars and black holes formed.
4. Magnetic fields that permeate space have often perplexed scientists and by studying the three dimensional maps of cosmic magnets, we may be able to understand how they stabilize galaxies and influence stellar evolution.
While the creation of a vast radio telescope is tantalizing in itself and the scientific studies mentioned of great importance, there is one final study that is planned with SKA: the nature of gravity itself.
Was Einstein right with his laws of general relativity? The SKA will subject the theory to unprecedented scrutiny and, who knows, maybe will come up with some surprises that will change our view of the Universe for ever.