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The Night Sky of April

Dr. Wayne Wooten
Professor of Astronomy

For April 2024, the last quarter moon occurs on April 1st. It is a week until the best total solar eclipse of most of our lives with the new moon on April 8th. On April 6th, the moon passes just below Mars (on top) and Saturn in the dawn sky, a great photo opp. Then two days later, the moon’s umbral shadow crosses the center of these United States for the last time in 21 years!

Having seen two totalities and one even more exciting broken annularity in May 1984, I assure you the three-four minutes of totality in the umbra is the greatest sky show you will ever see…so dark, cold, eerie, and with the chance to see a Comet as well as Venus (lower right) and Jupiter (upper left) of the eclipsed sun during the totality, which since the moon is closer and larger now than in August 2017, means this eclipse will last twice as long and give us a much darker sky.

If you are lucky enough to be in the umbra, remember that through out the partial phases, the bright photosphere is still partly visible, and safe viewers are mandatory! But once the moon completely covers the Sun, for those glorious minutes, whip off the glasses and enjoy the black disk of the moon in front of the sun, with red prominences all along its edge, and the glorious solar corona.

Of course, the partially eclipsed crescent sun (over half gone by maximum coverage around 2:30 locally) is also dramatic, especially if your telescope captures an erupting prominence on the cusp of the solar and lunar limbs. If past weeks are to be a judge, we expect large, complex sunspots to be rotating across the solar disk on April 8th, and they will help us track the progress of the Moon across the face of our star.

And what about that comet that might flare brightly enough to be seen in the sky of totality, between Jupiter and the Sun? Its name is Comet Pons-Brooks, and it has flare brightly in the last several months, and last week developed a tail that I photographed with my 50mm See Star digital telescope. By April it may become visible with the naked eyes below Jupiter in the western twilight. Check the www.spaceweather.com daily post for updates on its progress, and also more tips on capturing the eclipse and sharing your best shots in their gallery.

Because the moon will be about as close to Earth as it can get, and we are also near aphelion, most distant from the Sun, making it appear smaller, note how much broader the umbra will be in 21 years! Something to live for!

After this climax on April 8th, the month goes on. On March 11th, the waning crescent passes just north of Jupiter in twilight, and reaches first quarter on April 15th. The Full Moon, the Worm Moon, will be on April 23rd, but the last quarter moon will wait until May 1st.

Mercury and Venus are too close to the Sun to observe, except during totality when Venus will be 15 degrees west of the Sun, and Mercury just above it. Mars overtakes slower moving, more distant Saturn in the dawn sky on April 11th, only the diameter of the moon apart, a striking view with the naked eyes and a fine photo opp. Jupiter also overtakes much smaller, more distant Uranus on April 20th. Here is the telescope view of the giant, his four moons, and Uranus.

Jupiter vanishes into the Sun’s glare in early May, and Saturn and Mars are both in the dawn, so not a great month for telescopic observations on the planets. But Comet Pons-Brooks will be nice in binoculars, and perhaps visible low in the west with the naked eye, if it has another of the several outbursts it has shown us in the last several months, but this is entirely unpredictable!

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, Sirius is the closest star we can easily see here.

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. 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, but now trapped by our Galaxy’s gravity.

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. There is indeed a rich harvest in Virgo, of galaxies. The supercluster that lies in the arms of Virgo has more than a thousand members visible in our telescopes, and actually gravitationally bonds our own Milky Way and Local Group of Galaxies to it.

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