Other Solar Systems

Is our Solar system unique in the Universe ? Until recently, astronomers could only guess whether other stars are orbited by planetary systems. Extrasolar planets – those that orbit stars other than the Sun – are difficult to detect, because they are about one – billionth the brightness of their parent stars.

Extrasolar planets can also be detected by watching for a drop in brightness as a planet transits, or passes in front of, its parent star. The changing brightness of the star can be plotted on a graph called a light curve.

Another proposal, called gravitational microlensing, is to watch for sudden brightening as the planet’s gravitational field acts like a lens and magnifies the light from a more distant star.

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