Transit of Venus helps fine- tune the search for extraterrestrial life

Eclipse- like event won’t come again for more than a century

The passage of Venus in front of the sun today is a rare opportunity for astronomers to fine- tune the tools they use to search for planets that could support life outside of our solar system.

Our sister planet won’t pass between the sun and Earth again for more than 100 years. Weather permitting, the socalled Transit of Venus will be visible from Vancouver starting at 3: 06 p. m. and reaching its peak at 6: 25 p. m.

Scientists will use the opportunity to test the methods they use to find planets circling distant stars and to determine which of them might have an atmosphere capable of supporting life, according to Harvey Richer, an astronomer at the University of British Columbia.

Thousands of extra- solar planets have been discovered in the Milky Way Galaxy over the past 20 years using spacebased instruments tuned to detect the dimming of stars as planets cross in front of them, Richer said.

“It’s the same thing as the Transit of Venus, we just watch to see when they get dimmer,” he explained. “By monitoring the brightness of the sun just before and during the transit, we can observe this very small effect.”

At the moment that Venus begins to pass in front of the sun, its atmosphere is brightly lit allowing scientists to observe the components of its atmosphere, which they hope will aid them in the search for extraterrestrial life.

“At first contact, the light from the sun is passing through the atmosphere, so if you take careful spectroscopic measurements you can learn about the atmosphere of Venus,” Richer said.

Spectroscopic observation is the same method astronomers use to look into the atmosphere of extra- solar planets, in hopes of finding Earthlike conditions.

Because we know so much about the atmosphere of Venus, the measurements will allow scientists to determine if their instruments and methods are accurate enough to determine the composition of the atmosphere of planets circling faraway stars.

“The holy grail here is the question of whether there is life on extra- solar planets,” he said. “This is our chance to [ prove] the kind of observations we are doing of extra- solar planets.”

Today’s transit will take place during a period very close to the “solar maximum,” when the sun’s brightness is near its peak.

“We have an opportunity to measure the effect of a planet in transit during a time when the sun is quite active, Richer said. The new data — and that collected during our sun’s quieter periods — will help scientists fine- tune their search for planets around stars throughout their solar activity cycle.

Though the last Transit of Venus took place just eight years ago, no scientist living today will see another.

“This is our last shot at it,” Richer said.

Professors and students from UBC will be outside the Hennings Building this afternoon, weather permitting — beginning about 2: 30, until sunset — to assist people who want to see the transit. Small telescopes, dark viewing glasses and crude homemade pinhole cameras will be available. Showers are expected to ease late in the day.

If you don’t have proper viewing equipment, don’t risk your sight by looking at the sun. Live webfeeds of the event are being broadcast by observatories around the world through the National Aeronautics and Space Administration website at sunearthday. nasa. gov/.