Total solar eclipse in France, 1999. (Credit: Luc Viatour)

2009 is the International Year of Astronomy, and on Wednesday, July 22, the longest total solar eclipse of the 21st century will occur. You’ll need to be in the Eastern hemisphere to see it.

The eclipse’s totality path (the track of the Moon’s umbral shadow across Earth, where the eclipse is total) will pass through India, Tibet, China and some of Japan’s southern small islands; but will miss Hong Kong and the Korean peninsula. Greatest eclipse will be in the Pacific Ocean and will last 6 minutes, 39 seconds. Partial eclipses will be visible across India, Asia, Micronesia, and the Pacific Islands. Hawaii will experience a minimal partial eclipse in the late afternoon on the 21st.

If you’ve forgotten your grade school science, solar eclipses occur when the Moon, in new moon phase, passes between the Earth and Sun, fully or partially covering the Sun. A total solar eclipse is rare. Two to five solar eclipses can occur each year (typically about two occur); zero to two of those can be total eclipses (but they average one every year or two).

NASA Eclipse website: http://eclipse.gsfc.nasa.gov/eclipse.html

via Clark Planetarium