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The Night Sky of April

Dr. Wayne Wooten
Professor of Astronomy

For April 2016, the Moon will be new on April 7th. On the previous morning, April 6th, the waning crescent moon passes very close to Venus in the dawn, both rising about an hour before sunrise. The Moon is first quarter on April 14th. The waxing gibbous moon passes 2 degrees south of Jupiter on April 18th; try catching both of them in the daytime sky about 2 hours before sunset in the eastern sky. The Full Moon is on April 22nd, and is the Strawberry Moon; it washes out the peak for the Lyrid Meteor Shower that morning. The waning gibbous moon passes 5 degrees north of Mars on April 25th, then 3 degrees north of Saturn a few hours later. The moon is last quarter on April 30th.

Mercury is well placed for evening viewing about midmonth in the western sky, reaching greatest eastern elongation on April 18th, but disappearing into the sunís glare by monthís end. On May 9th, it will pass directly in front of the sun, a transit that will start locally about 6 AM sunrise, and end about 1:30 PM with Mercury leaving the sunís disk. Venus is rapidly vanishing behind the sun, and will not come back out in the evening sky until late summer. Mars and Saturn are both in Scorpius in the morning sky, but we are overtaking Mars, and it is getting closer and bigger and brighter by the day. It rises about 11 M at the start of April, but is up by 9 PM at monthís end. Opposition day is May 22nd, when Mars rises at sunset and is the brightest it has been since 2003. The reddish color is notable with the naked eye, and the telescope will reveal its polar caps, dark lava flows, and transient clouds in its atmosphere.

Jupiter is well up in the eastern evening sky as April begins. It now sits just east 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 11 PM as April begins, and reaching opposition on June 3rd. The ringed wonder is at its best in the east north of bright red Antares in Scorpius, with brighter red Mars to the upper right of them. the most beautiful object in the sky. When viewed with a telescope, the rings are open 26 degrees open and double the planetís disk brightness, 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.

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. 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. 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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