How has radar been used in astronomy?

A French fighter plane developed in the 1990s known as Rafale uses a device to help the jet evade radar. The Rafale uses technology called active cancellation, which receives an incoming wave and sends out the direct opposite pattern of that wave, in this case a radar wave half a wavelength out of phase with the incoming radar. When the two waves interfere with one another, the waves experience destructive interference canceling out the signal. Because there is no return signal, the enemy can’t find the location of the plane.

In radar astronomy electromagnetic waves are aimed at planets. By analyzing the reflected signals, the position, velocity, and shape of objects in our solar system can be determined. In the early 1960s, radar was used to determine the exact distance between Earth and Venus and Earth and Jupiter. Later, radar was installed on the space probe Magellan to map the surface of Venus. Radar astronomy has been beneficial in determining distances in our own solar system, but the reflected signals would be much too weak from objects outside our solar system.


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