For April 2020, the first Full Moon, the Egg Moon, is on April 7. The last quarter moon passes below Jupiter on April 14, and then Saturn in the 15th, and below Mars on the 16th in the dawn sky. The new moon is April 22. The crescent moon passes below the crescent Venus on the evening of April 26. The first quarter moon returns on April 30, setting length of the synodic (phase based) month as 29.5 days.
Mercury is too close to the Sun this month for naked eye observing. Venus dominates the western sky, passing below the beautiful Pleiades star cluster from April 1 through April 3. On April 11, Venus passes north of the much larger V of the Hyades cluster, the head of Taurus, with its eye the bright orange star Aldeberan. Telescopically, Venus crescent phases thins from 46% lit on April 1 to 24% on May 1, while as it retrogrades between us and the Sun and gets closer to us, its disk grows from 25” to 39” this month.
The superior planets all lie in the dawn sky this month. Mars passes just south of Saturn on April 1st, and continues moving east all month. Jupiter gradually draws closer to fainter Saturn in Capricorn all month as the two giants converge.
While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. For a detailed map of northern hemisphere, visit the www.skymaps.com website.
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!
Out at the edge of our Galaxy are hundreds of globular star clusters, and one of the finest lies just east of Arcturus. It is the third entry in Messier’s listing of smudges in the sky that did not move and thus were not his beloved comets. M-3 is visible as a compact blur in binoculars, and resolves itself into thousands of stars at about 100X in scopes six inches or larger. When it comes to comets, we have one that may arise to naked eye activity in late April. It may be up to naked eye visibility in the northwestern sky in Perseus by the end of this month, and at its best by mid-May. Stay tuned; such comets are unpredictable; the parent body to this comet put on a grand display in 1844!
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.
For more information on the Escambia Amateur Astronomers, join us on Facebook at “Escambia Amateur Astronomers”, visit www.eaaa.net or call our sponsor, Lauren Rogers at Pensacola State at 484-1155 or email@example.com. For more info, contact Dr. Wooten at firstname.lastname@example.org.