An astronomical rarity: Venus moving across the sun in May

It’s a setup of cosmic proportions. May starts with super bright Venus extraordinarily high in the western sky, but the planet falls out of view by month’s end, leaving us earthlings positioned for one of nature’s rarest of events: A transit of Venus across the sun on June 5 and 6.

Venus is high in the western sky at sunset. The negative fourth magnitude object is bright enough to fool airplane pilots into thinking it’s another plane. Right now, it sets around 11:30 p.m.

The young, crescent moon approaches Venus on May 21. It creeps closer to Venus on May 22 and then moves away May 23.

On May 24, Venus hangs low in the western sky, and it sets around 10 p.m. Enjoy the bright evening planet while you can, because its nights are numbered. In the evenings late in May, Venus is lost in the sun’s glare, as both the sun and Venus together retreat below the horizon.

The reddish planet Mars, a close cosmic friend these past few months, flashes less brilliance. Our neighboring planet is high in the southern sky at nightfall, while Monday and Tuesday evenings, the waxing gibbous moon pays a visit. It’s a zero magnitude object now, bright enough to see from urban skies, but it becomes a little more dim as May progresses. By month’s end, it starts the evenings in the southwestern sky.

Saturn, replete with its wondrous rings, loiters low in the southeastern sky at sunset. This zero magnitude (bright), big gaseous planet climbs higher in the southeast during dusk throughout May. (Find it now in the constellation Virgo.) Over the late spring and through late summer, Saturn and Mars appear to chase each other.

The sun’s glare obscures Jupiter now.

In late May, an annular solar eclipse starts in the future and ends in the present. An annular version is different from a total eclipse. The moon is too far from Earth to make a total, tight fit to completely obscure the sun. Thus, the sun forms a fatter ring around the moon.

Unfortunately for the Eastern and Central United States, it won’t be visible. The May 21 eclipse path starts along southern, coastal China, crosses Hong Kong, Taiwan and Japan, then skates along the Pacific before crossing the International Date Line, where it is still May 20. The eclipse visibility path approaches the Aleutians; the path makes landfall at the California and Oregon line, and ends passing through Nevada, Utah, Arizona and New Mexico.

Down-to-earth events

●April 29: Astronomy Night on the Mall, hosted by Hofstra University, with help from local astronomy clubs. On the Washington Monument grounds, near 15th Street and Constitution Avenue NE (across Constitution Avenue from the Ellipse). 7-11 p.m.

●May 5: Space Day: Welcome Discovery in Washington. Learn about the shuttle’s famous payload, the Hubble Space Telescope. Learn from astronaut Patrick Forrester about working in space. At the National Air and Space Museum on the Mall, 10 a.m.-3 p.m. www.nasm.si.edu.

●May 5: Space Day: Welcome Discovery in Chantilly. See the shuttle’s home at the James S. McDonnell Space Hangar. Meet astronauts Pam Melroy, Stephen Bowen and Tom Jones, at the Steven F. Udvar-Hazy Center in Chantilly. 10 a.m.-3 p.m. Free; parking, $15. www.nasm.si.edu