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The Night Sky of April

Dr. Wayne Wooten
Professor of Astronomy

For April, 2019, the waning crescent moon will be just south of Venus in the dawn an hour before sunrise on April 1st. The next morning, it will be below Venus and south of fainter Mercury 30 minutes before dawn. Binoculars will help spot elusive Mercury. The New moon is April 5th, with the waxing crescent moon south of the Pleaides and Mars on the evening of April 8th. The Full Moon, the Paschal Moon following the Vernal Equinox, is on April 19th, and sets the following Sunday, April 21st, as the date for Easter this year. On April 23rd, the Waning gibbous moon is close to Jupiter in the morning sky; it passes south of Saturn two morning later. The third quarter moon is April 26th.

Mercury is low in the dawn sky all month, much harder to see than brilliant Venus above it. Their closest approach is on April 16th, with Mercury 4.3 degrees to the lower left of Venus. Venus itself is on the far side of the Sun, and drawing closer to be lost in the sun’s glare next month. Mars is in Taurus in the western evening sky, and passes 6.5 degrees north of similarly colored orange giant Aldebaran on April 16th. Jupiter is in Ophiuchus, and rises about midnight in the SE in mid April. Saturn in east of the teapot of Sagittarius, and rises about two hours after its larger, brighter Jovian neighbor. Both will be well placed for our summer beach gazes this year.

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 hunter’s 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 dipper’s handle. Take the pointers at the front of the dipper’s bowl south instead to the head of Leo, looking much like the profile of the famed Sphinx. The bright star at the Lion’s 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. 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 earth’s 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 sun’s glare in the SW, you need to "get your corn in the crib"….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. Here is Chris Gomez’ fine shot with his 8" telescope of the Virgo Cluster.

In late April, skywatchers in the Northern Hemisphere will get a view of the Lyrid meteor shower, the dusty trail of a comet with a centuries-long orbit around the sun. The Lyrid meteors streak across the sky between April 16 and April 25, so skywatchers have a chance to see them during that window, weather permitting.

The peak of the Lyrid meteor shower will be extremely early in the morning on Monday, April 22 As with most meteor showers, the peak viewing time will be before dawn. According to Cooke, a waning gibbous moon (very close to full) will wash out all but the very brightest meteors this year during the peak, however.

The average Lyrid shower produces 15 to 20 meteors per hour; this year, the meteor shower may hit about 20 per hour. Some years, the Lyrid meteor shower intensifies and can produce up to 100 meteors per hour in what's called an "outburst," but it is difficult to predict exactly when that will happen. Although there is an average of 30 years between these outbursts, that's only an average; the actual number of years between the events varies.

Lyrid meteors will appear to radiate (the point from which the meteors appear to originate) will be high in the evening sky in the constellation Lyra to the northeast of Vega, one of the brightest stars visible in the night sky this time of year. Don't look directly toward the radiant, though, because you might miss the meteors with the longest tails.

The moon will be really favorable for them this year; it will set by the time the Lyrid radiant is high in the sky, the moon will be around first quarter, so the moon will have set by the show getting fired up after midnight. The Lyrid meteor shower is of medium brightness, but not as luminous as the famous Perseid meteor shower in August, which tends to produce more prominent trails.

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