(KPLR) - A wonderful celestial event is taking place this weekend, and - weather permitting - you can see it happen.
Rain and possible thunderstorms are in the forecast for Sunday evening.
Rich Heurmann of the St. Louis Astronomoical Society told us about the upcoming solar eclipse.
PARTIAL ECLIPSE OF THE SUN VISIBLE FROM ST. LOUIS
Sunday, May 20, 2012 at Sundown
A partial eclipse of the sun will be visible from St. Louis, weather permitting, on Sunday, May 20. The partial phase begins at 7:25 p.m., with the sun close to the horizon. The sun sets while in eclipse, at 8:05 p.m. 53% of the sun`s disk will be covered by the Moon.
A solar eclipse occurs when the Moon passes directly between the Earth and the Sun. The eclipse is visible along a band of ground - where the Moon`s shadow hits the Earth`s surface. The eclipse is total only from a very narrow strip centered on the band, and only when the Moon is close enough in its slightly egg-shaped orbit for the shadow to reach the ground.
The May 20 eclipse is 'annular' along the narrow strip. The Moon is too far away for the shadow to reach the ground. From the narrow eclipse strip, the sun will appear to be a black disk surrounded by a ring of fire. From a much broader band, only the edge of the shadow reaches the ground, and the eclipse is partial. The Moon covers up only part of the sun`s disk. St. Louis is in the partial eclipse band.
It is extremely dangerous to view a partial or annular eclipse, even near sundown when the sun`s light is greatly dimmed, through binoculars or a telescope. These instruments concentrate a large amount of solar energy into a tiny area. That energy is strong enough, in less than a second, to burn a hole in the retina of any viewer looking directly at the unfiltered sun.
Blindness is the immediate and irreversible result. A telescope may be used, with great care and by an experienced observer, to view a projected image safely. Special solar filters, which attach to the front end of the telescope or binoculars, may be used if great care is taken.
Solar filters that attach to the telescope eyepiece are very dangerous and should be discarded unused. The heat concentration can crack the filter, allowing direct sunlight through and blinding the viewer.
Weather permitting, some Astronomical Society members will be viewing the eclipse from the World`s Fair Pavilion in Forest Park. The next solar eclipse visible from St. Louis will be a partial eclipse on October 23, 2014.
The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend its meetings, telescope observing sessions, and special events. For information about Astronomical Society events, please visit the website, http://www.slasonline.org , or call (314)935-4614.
# # #
Saint Louis Astronomical Society
Associate Member, NASA Missouri Space Grant Consortium
At Washington University in Saint Louis
Campus Box 1169
EPSc, One Brookings Drive
Saint Louis, MO 63130-4899