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On June 5 at 6:03 p.m., observers of the Washington sky will be able to see one of the rarest of astronomical events: For several hours, Venus will appear as a small black dot floating across the surface of the sun. The Venus Transit occurs when the planet crosses between the sun and Earth. We get tips for safe backyard viewing, and find out how this rare event--which has occurred only six times since the invention of the telescope--allowed scientists to determine the distance between the sun and Earth.
The Venus Transit as seen from around the world on June 8, 2004, the last time the spectacle occurred.
The Washington sky will feature the rarest of astronomical events Tuesday at 6:03 p.m.: For several hours, Venus will appear as a small black dot floating across the face of the sun.
The Transit of Venus occurs when the planet crosses between the sun and Earth. The spectacle, which was first observed by German astrologer Johannes Kepler in 1639, follows an odd cycle. Two transits occur within eight years of each other, followed by a break of either 105 or 121 years. The last transit was on June 8, 2004. Scientists say the next event can be observed in 2117.
Since it was first observed, the Transit of Venus has played a crucial role in our understanding of space. By comparing Venus's journey during the Transit from different points on Earth, early scientists were able to determine the distance between our planet and the Sun. This week, scientists at NASA's Solar Dynamics Observatory will use the Transit to help calibrate its instruments and learn more about Venus’s atmosphere.
Tips for observing the Transit of Venus
If you want to observe the Transit, do not look directly at the sun. The sun's rays can cause serious damage to your eyes. NASA's Goddard Space Center offers the following recommendations:
Viewing with Protection
Use special solar glasses or #14 (or stronger) welder's glass, available at most hardware stores.
Telescopes with Solar Filters
The event is best viewed directly when magnified, which
demands a telescope with a solar filter. A filtered, magnified view will clearly show the planet Venus and sunspots. Never look through a telescope without a solar filter on the large end of the scope.
These are a safe, indirect viewing technique for observing an image of the Sun. While popular for viewing solar eclipses, pinhole projectors suffer from the same shortcomings as unmagnified views when Venus approaches the edges of the Sun.
Find local viewing events
Several local schools and astronomy clubs are holding events to view this rare celestial show.
The National Institute of Standards and Technology, in collaboration with Montgomery Blair High School in Silver Spring, Md., will host a Transit of Venus observation at the high school.
The Occoquan Town Council’s regular meeting Tuesday will be outdoors in conjunction with the transit of Venus, weather permitting. Mayor Earnest W. Porta Jr. will have a telescope with a solar filter available on the Vulcan Materials property, 10000 Ox Rd., Lorton, for the public to see Venus cross the face of the sun. Although the entire transit will not be visible, the transit should begin about 6 p.m. The council meeting will begin at 7 p.m. For information, visit www.occoquan.org and www.transitofvenus.org.
The Smithsonian National Air and Space Museum in downtown Washington, D.C., is hosting a special look at Venus as it passes between Earth and the Sun. Astronomy educators and museum volunteers will assist you in viewing the transit through safe solar telescopes. This is a must-see opportunity and the last chance to view the transit in our lifetime. The telescopes will be set up outside, on the Jefferson Drive (National Mall) side of the Museum. Admission is free. The special viewing will take place weather permitting. Observe the transit from 6 p.m. to 8 p.m. There will also be activities inside the Museum to demonstrate the significance of the transit. Free lecture from 8 p.m. to 9 p.m. in the Lockheed Martin IMAX Theater. More information.
In celebration of Sun-Earth Day, the Friends of the Arlington Planetarium will be hosting a transit viewing as their June Night at the planetarium event. Telescopes, sunspotters and viewing glasses will be available. In case of rain, they will meet inside W-L High School for a live Webcast of the event in Hawaii. The event will be held at 1300 Quincy Street, Arlington, Va.
Join a viewing of the Venus transit at Montgomery College, Rockville campus. They will have solar scopes and solar viewing glasses. If it's cloudy the NASA webcast will be streamed indoors. Details and directions here.
The transit of Venus (part one):
The transit of Venus (part two):
Videos courtesy NASA Goddard Space Flight Center