Transits of Venus—the movement of Venus across the face of the Sun—occur in pairs that are eight years apart and then don’t happen again for more than a century. Prior to the current pair, the last two Venus transits were in 1874 and 1882. After the transit in 2012, there won’t be another pair until 2117 and 2125. These rare alignments have been important for scientific research. Of particular significance, Venus transits provided observers with data that eventually led to a very close estimate of the astronomical unit—the distance between the earth and the sun. (See 1761 and 1769 on the timeline and the tab Why Is It Important?) Browse the timeline to learn some of the history of Venus transits along with related scientific ideas and breakthroughs.
2012 Transit, June 5–6
We will webcast the transit from Hawaii. Many people throughout the world will also be able to see at least part of the transit in person. Find out where and how to view it by clicking on the tab What Will You See?
2004 Transit, June 8
The Exploratorium sent a crew to Greece to webcast the transit. View the webcast archives and still photos from 2004.
Live Webcast of the 2012 Transit
The webcast will have a telescope feed plus audio commentary every 30 minutes. The duration of the program will be about six-and-a-half hours, beginning at 22:00 UT (noon in Hawaii) on June 5. First contact is at nine minutes past the hour. Find out what time the webcast starts in your time zone.
Mauna Loa Observatory
The Exploratorium will webcast the transit of Venus from Hawaii’s Mauna Loa Observatory (MLO), which
is located on the north slope of the Mauna Loa volcano at an elevation of more that 11,000 feet
(almost 3400 meters). More
Videos of the Mauna Loa Observatory coming soon.
