How can the sun be in two places at once? On April 19, the sun enters the sign of Aries astronomically and one day later enters the astrological sign of Taurus but still, in reality, is in Aries. How can this be? The answer lies with precession and apparent shifting of the stars on the celestial globe to an Earth observer caused by a wobble in the Earth’s direction of spin as it orbits the sun. It takes roughly 25,800 years for the wobble to complete a circle of 360 degrees. Astrology divides the zodiac, the annual path of the sun across the sky, into 12 houses of 30 degrees each. Thus, it takes about 2150 years for the sun to move from one house to the next. In the roughly four millennia since astrology had its beginning, the sun has shifted houses, as we see in the case of Aries and Taurus. If astrology took precession into account, the discrepancy would disappear.

Focus on the planets

Mercury may be seen by mid-month very low on the western horizon about an hour after sunset. On April 19, Mercury lies to the lower left of the thin crescent moon.

Venus dazzles well up in the west, as darkness falls and stays up for three hours after sunset. Venus climbs a bit higher with each passing night and, by month’s end, is more than a third of the way up the horizon.

Mars continues its descent into the glare of the setting sun and is barely visible in the west an hour after sunset. On April 19, Mars lies just above and to the left of Mercury with the crescent moon to the pair’s immediate left.

Jupiter shines high in the south at dusk and is up to nearly dawn. Telescopes will reveal the giant planet’s alternating belts and zones as well as the fascinating dance of its four major moons around and across its surface.

Saturn rises in the southeast around midnight as April opens but then earlier each night coming into view around 9:30 p.m. as the month closes. A favorable ring tilt offers spectacular viewing as does the major moon Titan.

Uranus and Neptune effectively are lost in the sun’s glare during April.

April events

1 Sunrise, 6:17 a.m.; sunset, 7:02 p.m. Moon at apogee or farthest distance from Earth.

4 Full moon, 8:06 a.m. The full moon of April is called the Worm Moon, Grass Moon or Egg Moon. There will be a total eclipse of the sun, but all that will be visible to those in the northeast is a slight darkening of the moon before it sets. Even for viewers on the West Coast, totality will be less than five minutes, the briefest totality for this century.

5 Easter. Originally calculated as the first Sunday following the full moon on or after the spring equinox.

8 Saturn is to the right of the moon as dawn breaks.

11 Venus shines in the west with two star clusters, the Hyades to its upper left and the Pleiades to its immediate right, respectively.

12 Moon in last quarter, 11:44 a.m.

17 The moon is at perigee, or nearest approach to the Earth.

18 New moon, 2:56 p.m.

19 The sun enters Aries on the ecliptic. Look to the west about 45 minutes after sunset to spot the thin crescent moon, Mars and Mercury forming a tight triangle very low on the horizon.

20 The sun enters the astrological sign of Taurus even though, astronomically, it has only entered Aries.

23 Peak night for the Lyrid meteor shower. The waxing crescent moon will set around midnight leaving the rest of the night free for viewing. Expect about a dozen sightings per hour, though one source says they could reach 15 to 20 per hour. In 1982, a spectacular display reached 250 meteors per hour.

24 Today marks the 25th anniversary of the launching of the Hubble Space Telescope in 1990.

25 First quarter moon, 7:55 p.m. Jupiter reigns in the west with the moon to its lower right.

29 The moon is at apogee for the second time this month.

30 Sunrise, 5:27 a.m.; sunset, 7:39 p.m.

Send astronomical queries to Clair Wood at cgmewood@aol.com or care of the Bangor Daily News, Features Desk, P.O. Box 1329, Bangor, ME 04402.