Mercury Gets Its Bright, Shining Moment on the Western Horizon

By Blaine P. Friedlander Jr.
Special to The Washington Post
Sunday, May 4, 2008

May is a long month with a solar system full of action. The evenings open with Mercury in the western sky stealing attention from larger planets, including Saturn and Mars, which entertain sky gazers high above the horizon.

Usually, Mercury is hard to see, but this fleet planet is quite visible now in the western sky after dusk. Just after sunset, the planet is about 17 degrees above the west-northwestern horizon, and on Tuesday, Mercury is joined by a new crescent Moon. (Thin crescent moons in the western sky are always new moons, and they set shortly after the sun. Conversely, full moons always rise in the east, opposite sundown in the west.)

Mercury will be at zero magnitude, bright enough to see from the city, but make sure you have a good view of the western horizon. At mid-month, Mercury puts a little more cosmic distance between itself and the setting sun, which means we get to see Mercury's beauty for a little longer after sunset.

However, after the middle of May, Mercury nudges closer to the sun. By the end of the month, this planet will be hiding, once again, in the sun's glare.

Of the two planets -- Saturn and Mars -- on center stage at sundown, Saturn is the brightest and easiest to find. The ringed planet is at zero magnitude and high in the southern sky after dusk, loitering as usual with the constellation Leo. You'll see it due south about 60 degrees from the horizon. The dim Mars, visible after dusk, high in the south-southwestern sky, hangs out between the constellations Gemini and Cancer.

And speaking of Mars, on May 25, NASA's Phoenix Mars Lander will land on the planet's arctic surface to examine the polar region in great detail. It was launched in August from Cape Kennedy, Fla., and its instruments will look for evidence of water and carbon-containing compounds and report atmospheric processes. Follow the mission's progress at http://phoenix.lpl.arizona.edu.

For night owls, Jupiter ascends the east-southeast about 2 a.m. now, and by sunrise, the large gaseous planet is due south. Look for this negative second magnitude (very bright) object to the east of the constellation Sagittarius. By month's end, Jupiter climbs from the eastern sky about two hours earlier, giving gazers grand opportunities to enjoy this planet's splendor on the morning side of night.

If you are looking for Venus, don't bother. This effervescent planet will return in late summer.

Down-to-Earth Events

· Tomorrow -- "Stars Tonight," a planetarium program describing May's night sky, 7:30 p.m., at Arlington County's David M. Brown Planetarium, 1426 N. Quincy St., adjacent to Washington-Lee High School. Information: 703-228-6070.

· Tomorrow -- Astronomer Mia Bovill discusses "Near Field Cosmology (or The Little Galaxies That Could)," at an open house, University of Maryland Observatory, College Park. Afterward, enjoy the stars and planets through a telescope, weather permitting. 9 p.m. Information: 301-405-6555; http://www.astro.umd.edu/openhouse

· Saturday -- The Northern Virginia Astronomy Club celebrates "Astronomy Day 2008" at Sky Meadows State Park, in Fauquier County, 3-11 p.m. See the Sun safely through special filters by day and view the heavens through telescopes in the evening. Steve Squyres, Cornell astronomy professor and the lead scientist for the Mars rovers, will discuss recent Mars findings at 5 p.m. Parking: $4. http://www.novac.com.

· Saturday -- One day, might we see telescopes on the Moon? Paul D. Lowman of NASA Goddard Space Flight Center discusses "Astronomy From the Moon: Why, Where and How?" at the regular meeting of the National Capital Astronomers, University of Maryland Observatory, College Park. 7:30 p.m. See the sky afterward. http://www.capitalastronomers.org.

· May 15-- Barbara Thompson of NASA Goddard Space Flight Center explores the Sun-Earth connection in her lecture "Living With a Star." At the Lockheed Martin IMAX Theater, National Air and Space Museum. Doors open at 6 p.m. for an informal educational program. Special free showing of "3D Sun" at 7 p.m. Meet the lecturer at 7:30 p.m. The lecture begins at 8 p.m. Admission is free, but tickets are required. http://www.nasm.si.edu.

· May 20-- Astronomer Cole Miller lectures at an open house, University of Maryland observatory, College Park. Enjoy the heavens through a telescope after the talk, weather permitting. 9 p.m. Information: 301-405-6555; http://www.astro.umd.edu/openhouse.

· Friday through June 15-- "Larry, Cat in Space," planetarium program about sky watching, space travel, the Moon and human nature. Fridays and Saturdays at 7:30 p.m., with Sunday matinees at 1:30 and 3 p.m. Admission: $3 for adults; $2 for children and seniors. At Arlington's David M. Brown Planetarium, 1426 N. Quincy St., adjacent to Washington-Lee High School. 703-228-6070.

Blaine Friedlander can be reached atPostSkyWatch@aol.com