What's Up in the Night Sky

April 2020 - Vol. 24, No. 4

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This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

As the days lengthen, the stars of the Winter Triangle fade into evening's dusk. The "Big Dipper" asterism (Ursa Major) is well placed for viewing this month since it is almost directly overhead. Follow the curve of its handle to Arcturus (Bootes) and continue on the curve to Spica (Virgo). Regulus (Leo) is on the ecliptic (the path traced by the planets and Moon), just W. of overhead. Further W., on the ecliptic, find the Gemini Twins, Castor and Pollux, and finally the Pleiades asterism of Taurus.

MERCURY in the morning sky favors southern observers. VENUS in the evening sky passes through the Pleiades star cluster during the first week of April. Continuing her reign in the northern hemisphere, our sister planet reaches GIE (greatest illuminated extent) on April 27, when the crescent will be 38" and magnitude -4.7. MARS in the morning sky, pulls away from Jupiter and Saturn, moving rapidly eastward during the month toward Capricornus. JUPITER shines in the morning sky, rising around 1 am by month's end. SATURN will follow Jupiter every morning, rising shortly after its big brother who is moving to overtake it. URANUS is heading for conjunction with the Sun.. NEPTUNE will emerge in the morning twilight sky.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
02	Juno at opposition.
03	Venus 0.3 deg. S. of Pleiades (M45) Moon 1.3 deg N. of M-44 (Beehive) star cluster. Mercury 1.4 deg. S. of Neptune.
07	Moon at perigee, expect large tides. This month's full moon is called the "pink" moon or "grass" moon. It occurs quite near to lunar perigee and will be ~30 percent larger than the full moon that occurs near apogee. It will be brighter than average, so take a look if the sky is clear in your neighborbood. The full moon occurs this month at 2:35 UT on Apr. 8.
10	Venus at greatest heliocentric lat. N.
14	Jupiter 2 deg. N. of Moon. Pluto 1.2 deg N. of Moon, occultation parts of Antarctica.
15	Saturn 2 deg. N. of Moon.
16	Mars 2 deg. N. of Moon. Mercury at greatest heliocentric lat. S.
20	Moon at apogee.
21	Mercury 3 deg. N. of Moon.
22	Lyrid Meteor peak. The shower is estimated to contain 20 meteors at peak, this year the new Moon should not interfere with observing. Viewing from North America should be optimum.
26	Uranus in conjunction with the Sun. Vesta 0.1 deg. S of Moon, occultation from NE Africa, Middle East, S Kazakhstan, N & Central India, China, most of SE Asia, Philippines, S. Japan. Venus 6 deg. N of Moon.
27	Moon 0.7 deg S. of M-35 star cluster.
28	Venus greatest illuminated extent (GIE.)
30	Moon 1.6 deg N. of M-44 (Beehive) star cluster.

Lunar Almanac for April 2020

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 23	Deep Space Objects
	1st. Qtr 01	Planets & Moon
	Full 08	Moon
	Last Qtr 14	Deep Space & Planets

Topic of the month: Venus visits the Pleiades

This year, the bright planet Venus has been dazzling the northern hemisphere with her brilliant light. If you have been outside in the evening, you've probably seen it. As soon as the Sun sets, the magnificent planet Venus has been towering over the western horizon. This northern passage is not unusual, it is part of the regular cycle that repeats between Earth and Venus every 8 years. Because Venus and Earth are neighbors, it's no mistake that Venus is the brightest planet in our sky. Her magnificent brilliance can also be attributed to the fact that the surface is entirely cloud covered. On March 24, Venus will be at its greatest elongation from the Sun (commonly abbreviated GE.) At this time the planet is as far away from the Sun as can be seen from Earth. Venus is 47 degrees away from the Sun on that date, but soon begins heading toward the horizon.

This northern apparition of Venus began in November 2019 when the planet was moving into Capricornus, crossing the sky through Aquarius, Pisces, and Aries all the while hovering over the western horizon. Finally reaching the constellation of Taurus, known as the bull. This constellation is the home of the bright first magnitude star Aldebaran, that is connected to the Hyades star cluster by line of sight only. Some saw the Hyades star cluster as the jaw or face of the bull. It is the closest star cluster to the Earth, but Aldebaran is closer to us still.

Venus visits the Pleiades star cluster April 2020

In April 2020, the planet Venus makes a visit to the bright star cluster M-45, commonly known as the Pleiades. Located in the constellation of Taurus, this group of stars is said to have seven bright members, sometimes referred to as the Seven Sisters. One of the best known clusters in the sky, the stars were formed around the same time. They are shrouded in the wispy nebulosity that reflects their light and can even be noticed with the unaided eye.

This year's visit of Venus to the Pleiades begins around the first of April when our sister planet moves close to the cluster as seen in the large frame. This outline of Taurus and images come with the open source astronomy software program Stellarium that is often used at this site. If the sky is clear in the last few days of March, take a look at the sky and see how close Venus is to the M-45 cluster.

It is interesting that they are called the "seven" sisters, because most people can only see six of the cluster's 3,000 members without optical aid. This has given rise to a legend of a lost Pleiad. The brightest star is Alcyone (mag 2.9), the third brightest star in the constellation. The second brightest Pleiad is Atlas (mag 3.62) The other sisters are fainter, called Merope, Calaeno, Taygeta, Sterope, Electra, and Maia. Actually, there are some that aren't too hard to see, but they are located away from the main bright stars.

Pleiades image courtesy NASA, ESA, AURA/Caltech, Palomar Observatory

Many cultures in the northern hemisphere marked the Spring setting of the Pleiades as a time to begin planting for the new year. The Pleiades cluster was of great interest to Aztecs who marked the midnight culmination of the cluster they called "Tiānquiztli." The Sumerians called them Mul-mul, a name that means, "star star." The Akkadian name was "zappu" or "bristle", sometimes thought of as "hair brush." Although "western" astronomers thought of the stars poetically as sisters, in Mesopotamian reckoning, these were the "seven demons" and their name was at times given to the planet Mars who was the ultimate "bad boy" planet in their celestial divinations. These demons were known as "Sebetti" or "Sibitti."

(Pleiades Image provided by NASA, ESA, AURA/Caltech, Palomar Observatory)

The Virtual Telescope Project is offering an online observing session on April 3, 2020. Check it out if the sky by you is cloudy. If the sky is clear for you on that date, start checking as soon as the Sun sets. For the next few hours, Venus will close in on M-45 and slowly move back out.

--See You Under the Stars!
Astra for Astra's Almanac