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Tau Ceti

January 4, 2016

When Frank Drake launched the first search for extraterrestrial intelligence, in 1960, his first target was the nearby star Tau Ceti. The search turned up empty. But research in the intervening years has revealed that Tau Ceti could have planets. And it definitely has supplies of the raw materials for planets — small asteroids and comets that clump together to make bigger objects.

Some of the evidence of those planetary building blocks is a wide belt of dust around Tau Ceti. The dust is created when comets and asteroids collide. So the location of the dust reveals where these objects are.

Light from Tau Ceti warms the dust, which then glows at far-infrared wavelengths. To study the dust, astronomers used Herschel Space Observatory, which was sensitive to those wavelengths.

Its observations revealed that the dust belt is wide. If it were in our own solar system, it would stretch all the way from the asteroid belt to beyond the orbit of Pluto. The observations also show that there are no gaps in the dust belt, which means there are no giant planets like Jupiter circling inside it.

Other observations have hinted at the existence of planets somewhat larger than Earth close to the star. So the Tau Ceti system may resemble a truncated version of our own: small planets close to the star, and nothing but asteroids, comets, and dust beyond.

Tau Ceti stands in the south as night falls, in Cetus, the sea monster. It’s bright enough to see with the unaided eye.


Script by Ken Croswell, Copyright 2015

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