Mark your calendars. On Friday, Aug. 1, NASA scientists will broadcast and webcast the next total eclipse of the sun, live from China. Viewers can watch the event on NASA Television beginning at 6:00 a.m. EST. They can also watch it at the website for the Exploratorium in San Francisco starting at 6:30 a.m. EST (click here for a list of times by city).
During a total solar eclipse, the moon’s shadow falls on Earth. The shadow is cast when the moon passes directly between Earth and the sun. For a few seconds, the moon blocks the sun’s light. Spectators who live within regions where the shadow falls will witness the moon blocking out the majority of the sun’s light.
This particular eclipse will sweep across the planet in a slim path that begins in Nunavut, a northern province of Canada, and ends in northern China. So people in parts of Canada, northern Greenland, the Arctic, central Russia, Mongolia and China will be able to witness the seconds-long blackout.
When the moon totally obscures the sun — the moment of totality — the sun’s outer atmosphere, called the solar corona, becomes visible. The solar corona reaches temperatures higher than a million degrees Celsius and extends farther than 620,000 miles from the star’s surface. Because the sun’s surface is brighter than its corona, a solar eclipse is the only opportunity to see the corona with the naked eye (with proper eye protection. Click here for a guide.)
The last time the solar corona was seen during a total solar eclipse was on March 29, 2006. Spectators within a narrow corridor beginning in Brazil and extending across the Atlantic, northern Africa, central Asia and western Mongolia watched the moon overtake the sun.
The next total solar eclipse will occur on July 22, 2009. Viewers in India, China, a handful of Japanese islands and the South Pacific will be able to watch the sky grow dark as the moon takes over the sun once again.