By Blaine P. Friedlander Jr.
Special to The Washington Post
Sunday, June 1, 2008; C07

Summertime . . . and the viewing is easy: Mars is moving, Saturn's rings are open and Jupiter is bright.

In these nights leading up to summer's official start, Saturn and Mars anchor the southwestern heavens at nightfall. Mars is a dim first magnitude (it might be hard to see in Washington's light-polluted skies), while Saturn is a more robust zero magnitude, which is bright enough to see from the city.

The ringed planet is sitting near the front legs of the constellation Leo, the lion, where it has stayed for the past few months. Meanwhile, the rusty, red planet -- gaining more traffic from Earth, with the recent successful landing of NASA's Phoenix lander ( http://www.nasa.gov/phoenix) -- hangs out in the constellation Cancer right now. Early in June, you can spy Mars near the Beehive Cluster (M44). Now, Mars sets about 12:30 a.m. and Saturn sets near 1:30 a.m., both in the west.

Mars cannot sit still. Throughout June, pay attention to the evening's southwestern heavens. Mars moves into the constellation Leo and nudges closer to Saturn. Because Saturn is farther from the sun than Mars, it appears to Earthlings that Saturn stays in one place longer. In fact, Mars is closer to the sun and orbits it faster.

Jupiter climbs the eastern sky about 11 p.m. now. By June 15, it will rise closer to 10 p.m. On June 30, find it rising about 9 p.m.

With a mere minute to spare, summer officially starts June 20 for the first time since 1896, according to the U.S. Naval Observatory. The summer solstice, the season's official start in the Northern Hemisphere, kicks off at 11:59 p.m., Universal Time, formerly Greenwich Mean Time. For the eastern United States, summer begins at 7:59 EDT.

Get used to these rare, early summer starts; the next June 20 solstices will occur in 2012, 2016 and 2020.

In case you believe that objects cannot hit Earth, consider this: June 30 marks the 100th anniversary of the Tunguska event, during which an explosion -- probably caused by an asteroid in Earth's atmosphere -- completely leveled an area about twice the size of greater Washington. Scientists believe that an asteroid fragment over Tunguska, in the middle of Russia's Siberian region, blew up just before it would have hit the ground, and that the explosion's magnitude was equal to thousands of atomic bombs.

· Monday-- "Stars Tonight," a sneak preview of June's heavens, at Arlington County's David M. Brown Planetarium, 1426 N. Quincy St., adjacent to Washington-Lee High School. 7:30 p.m. Information: 703-228-6070.

· Thursday-- Astronomer Tony Farnham talks about the 100th anniversary of the Tunguska event at the open house, University of Maryland observatory, College Park. Afterward, see the heavens, weather permitting. 9 p.m. Information: 301-405-6555; http://www.astro.umd.edu/openhouse.

· Saturday-- "Exploring the Sky" at Rock Creek Park, hosted by the National Capital Astronomers and the National Park Service. Meet near the Nature Center in the field south of Military and Glover roads NW. 9 p.m. Information: 202-895-6070.

· Saturday-- See the night sky, as Sean O'Brien of the National Air and Space Museum leads a star party at Sky Meadows State Park, near Paris, Va. From 8:30 to 11 p.m. Parking: $4. Arrive before dark. Information: 540-592-3556.

· June 8-- Alan Goldberg, systems engineer, "Observation Planning for Hubble Space Telescope: Lessons From and for Amateurs," in a talk at the Northern Virginia Astronomy Club meeting. Room 80, Enterprise Hall, George Mason University, Fairfax. 7 p.m. Information: http://www.novac.com.

· June 14-- "Space: A Journey to Our Future," a new exhibit, opens at the National Air and Space Museum. This exhibit provides a glimpse to future human space travel. Information: http://www.nasm.si.edu.

· June 14-- Harold Williams, astronomer at Montgomery College, discusses stellar evolution at the regular meeting of the National Capital Astronomers, held at the University of Maryland Observatory, College Park. 7:30 p.m. Information: http://www.capitalastronomers.org.

· June 17-- Tom Bogdan, director of NOAA's Space Weather Prediction Center, on "Forecasting Space Weather" at the Lockheed Martin IMAX Theater, National Air and Space Museum. Bogdan's group provides space weather guidance for satellites, air transportation communications and the national power grid infrastructure. 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.

· June 20-- Astronomer David Rupke discusses "The Making of the Modern Telescope" at the open house, University of Maryland Observatory, College Park. See the stars and planets afterward, if skies are clear. 9 p.m. Information: 301-405-6555; http://www.astro.umd.edu/openhouse.

Blaine Friedlander can be reached atPostSkyWatch@aol.com.