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The Night Sky of April

Dr. Wayne Wooten
Professor of Astronomy

For April 2015, the Moon will be full on April 4th; this is the Paschal Moon, or Passover Moon, right after the Vernal Equinox, and sets next Sunday as Easter. This year it also is a total lunar eclipse, of which we locally will only see the beginning at moonset. Clear skies permitting, we will set up telescopes outside the Pensacola State College Planetarium about 5 AM, with the partial eclipse beginning at 5:16 AM, and totality starts at 6:58 AM, but for Pensacola, the Moon will set and sun will rise while the moon is only about half way into our shadow.

On April 8th, the waning gibbous moon passes 2.1 degrees north of Saturn. The last quarter moon is on April 12th. New moon is April 18th. The waxing crescent moon passes 7 degrees south of Venus at dusk on April 21th. The first quarter moon is April 25th, and the moon passes five degrees south of Jupiter overhead on the next evening.

Venus dominates the southwestern twilight sky. On April 1st, she is78% sunlit, 14" of arc across, and mag. -4, and by the end of the month, she pulls farther away from the sun, now 17 " across, up to mag. -4.1, and appears 67% sunlit. She will reach greatest eastern elongation on June 9th, when she appears half lit.

Mars is behind the sun now, but Jupiter is high overhead in the evening as April begins. It now sits just west of the Sickle of Leo. Its four moons are a treat with any small telescope, and larger scopes will reveal a lot of detail in Jupiterís clouds, including its famed Great Red Spot.

Saturn rises in the SE about 10 PM as April begins, and reaching opposition on May 23rd. The ringed wonder is at its best in the east in the claws of Scorpius. This is the best time to observe the most beautiful object in the sky. When viewed with a telescope, the rings are open 23 degrees open, to reach their greatest tilt of 27 degrees wide at its solstice in 2017, and Titan and several smaller moons fall on either side of the most beautiful telescopic sight in the sky. In addition to its glorious rings, Saturn hosts a huge moon, Titan, visible in most any telescope, and several smaller ones needing at least a 6" scope to spot.

Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the northwestern sky. It is part of the pentagon on stars making up Auriga, the Charioteer (think Ben Hur). Several nice binocular Messier open clusters are found in the winter milky way here. East of Auriga, the twins, Castor and Pollux highlight the Gemini. South of Gemini, Orion is the most familiar winter constellation, dominating the southern sky at dusk. The reddish supergiant Betelguese marks his eastern shoulder, while blue-white supergiant Rigel stands opposite on his west knee. Just south of the belt, hanging like a sword downward, is M-42, the Great Nebula of Orion, an outstanding binocular and telescopic stellar nursery. The bright diamond of four stars that light it up are the trapezium cluster, one of the finest sights in a telescope.

In the east are the hunterís two faithful companions, Canis major and minor. Procyon is the bright star in the little dog, and rises minutes before Sirius, the brightest star in the sky. Sirius dominates the SE sky as darkness falls. At 8 light years distance, Sirius is the closest star we can easily see with the naked eye from West Florida.

To the northeast, look for the Big Dipper rising, with the top two stars of the bowl, the pointers, giving you a line to find Polaris, the Pole Star. Look for Mizar-Alcor, a nice naked eye double star, in the bend of the big dipperís handle. North of the handle is the fine spiral galaxy M-101; this photo was taken by local amateurs Chris and Gina Gomez with their new 8" telescope; what a fine sight!

Take the pointers at the front of the dipperís bowl south instead to the head of Leo, looking much like the profile of the famed Sphinx. The bright star at the Lionís heart is Regulus, the "regal star".

Now take the curved handle of the Big Dipper, and follow the arc SE to bright orange Arcturus, the brightest star of the spring sky. Recent studies of its motion link it to the Sagittarius Dwarf Galaxy, a companion of our Milky Way being tidally disrupted and spilling its stars above and below the plane of the Milky Way, much like dust falling away from a decomposing comet nucleus. So this brightest star of Bootes the Bear Driver is apparently a refugee from another galaxy!

Now spike south to Spica, the blue-white gem in Virgo rising in the SE. Mars lies a little to the west of Spica in April, and is much brighter than anything else in the SE evening sky at opposition this month. Virgo is home to many galaxies, as we look away from the obscuring gas and dust in the plane of the Milky Way into deep space. To the southwest of Spica is the four sided Crow, Corvus. To the ancient Greeks, Spica was associated with Persephone, daughter of Ceres, goddess of the harvest. She was abducted by her suitor Pluto, carried down to Hades (going to Hell for a honeymoon!) and when Jupiter worked out a compromise between the newlyweds and the angry mother-in-law, the agreement dictated Persephone come back to the earthís surface for six months of the year, and Mama Ceres was again placated, and the crops could grow again. As you see Spica rising in the SE, it is time to "plant your peas", and six months from now, when Spica again disappears in the sunís glare in the SW, you need to "get your corn in the crib"Ö.so was set our calendar of planting and harvesting in antiquity. In the arms of Virgo is a rich harvest of galaxies for modern astronomers.

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