| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Skyguide Worlds Align (Again) April 5 On the first Sunday in April, most people in the U.S. adjust clocks forward one hour ("Springing forward" to Daylight Saving Time) at 2:00 a.m., but not in American Samoa, Arizona, Hawaii, Puerto Rico, the Virgin Islands, or most of Indiana, where Daylight Saving is not observed. April 11 Full Moon, traditionally also called the "Grass Moon" or "Egg Moon," located near the bright star Spica in Virgo. April 22 Peak of the Lyrid meteor shower, which typically averages about 15 meteors per hour. April 26 New Moon. The Muslim New Year begins at sunset, with the sighting of the first crescent Moon in the Middle East. May 6 Peak of the Eta Aquarid meteor shower, caused by dust from Halley's Comet. One of the better showers of the year for observers in the Southern Hemisphere, this display typically averages about 30 meteors per hour. May 11 Full Moon, also known as the "Planting Moon" or "Moon," just exiting the stars of Libra. By the time it sets with tomorrow's dawn, the Moon will have just crossed into Scopius, but it doesn't stay there long --only a narrow section of Scorpius intrudes between Libra and the constellation Ophiuchus (the Serpent-Bearer) where the Moon and solar system objects spend more time than in Scorpius. May 25 New Moon June 10 Full Moon, also called the "Rose Moon," and "Strawberry Moon," located against the stars of Ophiuchus. Since this is the closest full Moon to the summer solstice, observe how it follows a low arc across the sky--just the opposite of the Sun, which in June crosses the sky at its highest. June 14 Earliest Sunrise for the mid-northern latitudes (approxmately 40 degrees north). The Earth moves faster when it's closer to the Sun, in January, than when it's farther away in June and July. Combined with Earth's fairly uniform rotation, this causes the earliest sunrise to occur about a week before the solstice and the latest sunset about a week after. June 21 Summer solstice at 7:03 a.m. pdt. The Earth's axis, tilted 23-1/2 degrees from the vertical, is oriented with the north pole at its maximum inclination toward the Sun. Seen from Earth, the Sun is at its farthest point north of the celestial equator and rises and sets at its most northerly points on the horizon. It crosses the sky at its highest, resulting in the longest dayight of the year for the Northern Hemisphere. June 23 New Moon June 27 Latest sunset for latitude 40 degrees.
Mercury Not easily visible in April, Mercury appears in the morning sky in early May, reaching greatest western elongation on May 4, when it's only 27 degrees from the Sun. On morning of May 12, it might be easy--using binoculars--to spot Mercury less than a degree from Saturn low in the east in the predawn sky, with Mercury slightly outshining the ringed planet. Look very soon after sunset on the evening of June 25 for tiny Mercury very low in the west-northwest, about nine degrees to the left of a thin, waxing crescent Moon. Venus The brightest planet dominates the eastern sky before dawn. On the morning of April 23, Venus is less than half-a-degree from Jupiter, with the waning crescent Moon very near. This forms one of the closest groupings of these three objects in many years. It's even better for observers in eastern Brazil and southwestern Africa, who will see the crescent Moon blocking both from view at the same time. Mars In conjunction May 12, the Red Planet is washed from view pretty much for the whole quarter, though you may be able to glimpse it through binoculars very low in the west, near Saturn, just after sunset on April 1 to 3. Jupiter The largest planet is a morning object this quarter, gradually rising higher and higher in the east each dawn against the stars of Pisces. Don't miss its spectacular grouping with Venus and the Moon on the morning of April 23. Saturn In conjunction with the Sun on April 13, the Ringed Planet is washed from view by the Sun's glow until mid-May as it gradually rises higher and higher out of the predawn twilight. It's joined by Venus on May 28, and by the Moon on May 23 and June 19.
Bing F. Quock is a member of the Morrison Planetarium staff. |
Spring 1998
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