# How does the Square Kilometre Array pick up and record information?

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How does the Square Kilometre Array pick up and record information?

In: Physics

I assume you’re asking about how multiple telescopes can be used together to produce a single image.

Light is a wave (among other things). Each type of light has a frequency, meaning how many times it goes back and forth per second. Light that we can see is high frequency: it goes back and forth trillions of times per second. Radio waves only go back and forth millions of times per second, which is pretty slow for light. Because of this, for radio waves, we can capture not only how “bright” they are, but also what part of their back and forth motion (called their “phase”) they’re on. This is important, because when two light waves meet each other, how they interact depends on their phases. If their phases are the same, their brightness adds together. If their phases are opposite, their brightness cancels out.

Radio telescope arrays gather data from radio waves at each of their telescopes. Then, they combine this data–using both brightness and phase–as if all the light was falling on a single giant telescope, calculating how the light from each telescope would have interacted with the light from the other telescopes. Because bigger telescopes can see more detailed pictures, these arrays can make out very small and distant features in the sky, allowing us to learn more about the universe.

It can’t do anything yet because it hasn’t been built. When it is built and turned on, it will function like any other multi-antenna radio telescope. The dishes will be pointed at a part of the sky and the receivers in each of the dishes will feed their data to central processors.