There's a little black spot on the sun June 8.
From our earthly perspective, the planet Venus crosses the sun for the first time since 1882, and the event will be visible at sunrise in the Washington area. This solar crossing, or transit, is among the rarest of astronomical events.
The eastern half of North America gets to see the final portion of the transit, while Europe, Asia and Africa get a longer, better view.
Washingtonians can see the transit after sunrise, which is at 5:43 a.m., according to the U.S. Naval Observatory. Venus will be in the latter stage of the transit by that time. By 7:06 a.m., Venus will be exiting the sun's edge, and the event will be over by 7:26 a.m.
Because Venusian transits happen in pairs because of celestial mechanics -- albeit eight years apart -- the second transit in this set will be June 6, 2012. If you miss it, the next set will be Dec. 11, 2117, and Dec. 8, 2125.
Never look at the sun directly with the naked eye, or do something foolish such as use smoked glass or sunglasses -- you could go blind. Instead, for safety's sake, project the image through a telescope or binoculars onto white paper or poster board. (Never view the sun directly through the lens of a telescope or the lenses of binoculars, as this will increase the sun's intensity and blind you.) The pinhole-in-cardboard technique, popular for viewing solar eclipses, works for transits as well.
For eye-safety information, go to www.transitofvenus.org/safety.htm.
Through his research, astronomer Sten Odenwald of NASA's Sun-Earth Connection Education Forum has discovered that John Philip Sousa wrote the "Transit of Venus March" after the 1882 event. The Smithsonian Institution commissioned Sousa to write a march for the dedication of the Joseph Henry statue. (Henry, a scientist, was the institution's first director.) It was first performed April 19, 1883, and a modern recording by the Virginia Grand Military Band can be heard at a Library of Congress Web site, lcweb2.loc.gov/cocoon/ihas/html/venus/venus-home.html.
What happens when you mix astronomy and entomology? You get another rare event. Even more infrequent than the transit of Venus is a simultaneous visit by Brood X (17-year) cicadas. Odenwald calculated that the last time these cicadas emerged concurrently with a Venus transit was May 22, 797, and the time before that was May 23, 921 BC.
If you want to get up early and watch safely, the local events for June 8 transit will include:
* NASA Television, in cooperation with NASA's Sun-Earth Connection Education Forum and the Exploratorium in San Francisco, will Webcast the transit starting at 1 a.m. June 8 through the event's conclusion. You can reach the NASA TV Webcast through links at sunearthday.nasa.gov.
* The observatory at the University of Maryland is planning a public event to safely view the transit. For information, go to www.astro.umd.edu/openhouse
* Skygazers can go to the Black Hill Regional Park (20926 Lake Ridge Dr., Boyds) in Montgomery County to watch the transit through correctly filtered telescopes. The event, in cooperation with local astronomers, will begin at 5:15 a.m. and end at 7:30 a.m. (For ages 6 to adult.) Admission is $5; for Friends of Black Hill, $4. For information, call 301-916-0220.
* Montgomery College's planetarium has organized a viewing event. If the weather is clear, the event will be at the college's parking garage (top level) at Fenton and King streets, Takoma Park, from sunrise to 7:30 a.m. Details, www.montgomerycollege.edu/Departments/planet.
* The Fairfax County Park Authority's Observatory Park at Turner Farm in Great Falls will host a transit viewing event from sunrise to 7:15 a.m., where there will be properly equipped telescopes and binoculars. Turner Farm is at Georgetown Pike and Springvale Road. Information, http://www.fairfaxcounty.gov/parks/turnerfarm/index.htm.
* For detailed scientific information on the transit, visit a Web site developed by NASA astronomer Fred Espenak at sunearth.gsfc.nasa.gov/eclipse/transit/venus0412.html.
* June 7 -- William Borucki of NASA's Ames Research Center on "New Strategies for Detecting Life in the Universe," Einstein Planetarium, National Air and Space Museum. Free, but obtain tickets in advance. Information, email@example.com, or call 202-357-2700.
* June 19 -- View the cosmos with astronomer Sean O'Brien of the National Air and Space Museum at Sky Meadows State Park, near Paris, dusk to 11 p.m. $4 parking fee. Information, www.dcr.state.va.us/parks/skymeado.htm, or call 540-592-3556.
* June 19 -- "Exploring the Sky," presented by the National Park Service and the National Capital Astronomers at Rock Creek Park, near the Nature Center, in the field south of Military and Glover roads NW, 9 p.m. Information, capitalastronomers.org, or call 202-895-6070.