Thursday, June 21, 2012

The Transit of Venus Is Helping the Search for Alien Planets


How observing Venus moving between the Sun and Earth is useful in the hunt for alien worlds

[On June 5, 2012, Venus passed directly between the Earth and the Sun, a rare astronomical phenomenon known as the "Transit of Venus" that will occur again in 105 years. This month, 13.7 Billion Years considers "Earth's twin," from the scientific study of the planet to its mythological underpinnings, with the series Second Rock from the Sun.]

In the past, scientists’ interest in the transit of Venus centered around the fact that measuring it helped to measure the size of the solar system. 

While the recent transit did help get a more accurate measurement, this time around, astronomers put the transit to a different use: to help them in the ongoing search for alien worlds.

"Astronomers in the 18th and 19th centuries observed transits of Mercury and Venus to help measure the distance from Earth to the sun," said Frank Hill, director of the National Solar Observatory’s (NSO) Integrated Synoptic Program, according to Space.com.

The distances we have today are pretty accurate. "But transits are still useful," Hill said. "This one will help us calibrate in several different instruments, and hunt for extrasolar planets with atmospheres."

Since the Venusian atmosphere relatively well known, astronomers believe that observations made during the transit will provide a benchmark for studying exoplanet atmospheres during their own transits around distant stars.

It is very difficult to observe exoplanets directly, being so faint in comparison to their parent stars. Instead, astronomers use telescopes to detect “wobbles” in the light emanated by parent stars, which is caused when one of its planets is in transit. So far, NASA's Kepler space telescope has found more than 2,300 candidate alien planets using this "indirect" technique.

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image: Transit of Venus, 2004 (credit: NASA)

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