Wednesday, March 21, 2012

Mercury and Venus used to gauge the Sun

Captain James Cook more than two and a quarter centuries ago voyaged to Tahiti to view the transit of Venus across the face of the sun, in attempt to gauge the size of the solar system.

There is a cool NASA article about that here.

(Image: Images of Mercury’s path across the face of the sun, as viewed from NASA’s Solar and Heliospheric Observatory (SOHO) on November 8, 2006. Credit: NASA.)

Scientists are still doing that kind of seminal work, and researchers from Hawai`i, Brazil and California have just announced that the 2003 and 2006 transits of Mercury across the sun, measured from the SOHO satellite, have yielded the most accurate ever calculation of our sun’s size.

The radius of the sun is 432,687 miles, give or take 40 miles, they say.

Using a satellite gave the researchers a great advantage over Cook, since they could overcome the blurring caused by the Earth’s atmosphere. The researchers included Jeff Kuhn and Isabelle Scholl of the University of Hawai`i Institute for Astronomy, Brazilian astronomer Marcelo Emilio, who was visiting the Hawai`i institute, and Rock Bush of Stanford University.

And while they used Mercury for the latest measurement, they plan to observe the transit of Venus June 5, in an attempt to improve the accuracy of their measurement even more. Their paper on the work is here.

© Jan TenBruggencate 2012

1 comment:

John said...

This is a very beautiful and interesting research
The most educating one i have read today!

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