| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Skyguide April to June 2002 April 7: Most of the United States switches from Standard Time to Daylight Time at 2:00 a.m, and all PDAs, pagers, programmable thermostats, and other clock-controlled devices should be adjusted forward one hour. April 20: Astronomy Day. A beautiful chain of planets stretches upward from the west after sunset. Many amateur astronomy clubs will have telescopes set up this evening for up-close viewing. Peak of the Lyrid meteor shower, named after the constellation Lyra. This usually averages about 20 swift meteors per hour with occasional fireballs, but the light of the waning gibbous Moon may interfere with viewing. April 26: Full Moon, rising at sunset against the stars of the constellation Virgo. Known to the Celts as the “Growing Moon.” May 12: New Moon. By sunset at 8:10 p.m., West Coast skywatchers can view one of the thinnest Moons this year—a razor-sharp, 16 1/2-hour-old crescent. Look low in the west just after sunset. May 26: Full Moon. A penumbral lunar eclipse starts this morning at 3:13 a.m. and lasts until 6:54 a.m. But don’t get too excited about it: penumbral eclipses happen when the Moon passes through the outermost fringe of Earth’s shadow, so only a subtle darkening of the southern region may be noticed. June 10: New Moon. Tomorrow night, look for a thin crescent Moon low in the west just after sunset. An annular solar eclipse will be visible along a path that crosses the Pacific Ocean, but for most of the Pacific Rim, a partial eclipse will be seen (see box). June 21: Summer Solstice marks the beginning of Summer in the Northern Hemisphere, at 6:23 a.m. The Sun rises and sets at its northernmost points along the horizon, reaches its highest point in the sky at noon (for points on and north of the Tropic of Cancer), and spends more time above the horizon than on any other day of the year. June 24: Full Moon, rising against the stars of Sagittarius. Colonial Americans called this the “Rose Moon.” Yet another penumbral lunar eclipse occurs as this Full Moon skims the southern edge of Earth’s shadow. MERCURY: The smallest of the naked-eye planets has no small role in this season’s wonderful series of planetary encounters. In mid-April it takes its position as “anchor” of a striking line of planets and the crescent Moon extending upward from the west after sunset. The planet gradually climbs higher, reaching its greatest angular separation from the Sun on May 3, when it’s easiest to see. Then it starts to get lost in the twilight again. However, on May 13 you might be able to see Mercury just to the right of a razor-thin crescent Moon with binoculars. VENUS: The brightest planet is easy to identify as it has some close encounters with other objects. For a few days around April 25, look for the Pleiades star cluster just to the right of Venus. After forming a stunning triangle of worlds with Mars and Saturn on May 5, the planet has one of the closest planetary meetings of the year with Mars on May 10. On June 3, Venus passes less than two degrees from Jupiter. By the end of June, the other planets have been lost in the glow of the Sun, leaving only Venus in the evening sky. MARS: The Red Planet starts between Saturn (above) and Venus (below) in April. Watch as the planets gradually seem to close in from night to night until May 5, when they form a tight, spectacular triangle just after sunset. On May 10, Venus and Mars are only a third of a degree apart (less than the apparent width of a Full Moon), making them visible in the same telescope field at the same time. After that, Saturn and Venus will swap the positions they were in at the beginning of April, with Venus rising above Mars and Saturn dropping below. JUPITER: For most of the season, the largest planet stands bright and regal against the stars of the constellation Gemini after sunset. It hovers at the top of the line of naked-eye planets reaching upward from the west until Venus passes it on June 3. Due south at sunset on April 1, it gradually drops lower toward the west until it’s washed from view by late June. The Moon is nearby on the evenings of April 18, May 15, and June 12. SATURN: The slowest-moving of the naked eye planets, the Ringed Planet plods slowly through the face of Taurus this season about halfway up from the horizon just after sunset in early April. The crescent Moon passes by on April 16 and May 13. After mid-May, it starts drawing lower into the glow of the setting Sun until it disappears from view. Saturn is in conjunction with Mars on May 3 and with brighter Venus on May 6.
Times for San Francisco, CA; accurate to within two minutes.
Bing F. Quock is Chairperson of the Morrison Planetarium, California Academy of Sciences. bquock@calacademy.org |