May 2023 - Vol. 27, No. 5

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 May brings the lengthening days, the hours of nightly observation decrease as well, it is always with a bit of sadness that we say good-bye to the Winter and Spring constellations, Gemini, Leo, and Virgo. The early evening presence of Arcturus, the second brightest star in the northern sky, reminds us that the bright star clouds of the Milky Way will soon be brightening up those dark evenings when the Moon is small enough to allow us to truly enjoy those galactic treasures. As the evening turns to morning, the bright stars of the summer triangle follow until just before sunrise. The Milky Way is at the zenith, high overhead. Long twilight hours come to the northern hemisphere.

MERCURY is at inferior conjunction early in the month, reappearing in the morning sky by mid-month. VENUS is very prominent in the evening sky, reaching maximum declination of +26 deg, setting after midnight in the northern latitudes. MARS moves into Cancer, fading to 1.5 magnitude by month's end. JUPITER returns to the morning sky this month. SATURN in Aquarius, rises in the early morning sky. URANUS reaches conjunction with the Sun on the 9th. NEPTUNE rises in the early morning twilight.

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
01	Mercury at inferior conjunction.
05	This month's full moon is often called the "Flower Moon" due to the Spring blooms present in North America and other northern areas. A penumbral lunar eclipse occurs, greatest eclipse is over the Indian Ocean and it will not be visible from North America.
06	Eta Aquarid meteor peak. The shower produces up to 60 meteors at its peak. Dust particles for this meteor shower are generated by Halley's comet as it approaches the Sun on its 76-year orbit.
07	Alpha Scorpii, Antares, 1.5 deg. S. of Moon.
09	Venus at greatest heliocentric lat. N. Venus 1.8 deg. N. of M35 Uranus in conjunction with the Sun.
11	Moon at perigee.
13	Ceres stationary Saturn 3.0 deg. N. of Moon.
14	Mercury at aphelion. Mercury stationary.
15	Neptune 2 deg. N. of Moon
23	Venus 2 deg. S. of Moon.
24	Alpha Geminorum, Pollux, 1.6 deg. N. of Moon. Mars 4 deg. S. of Moon.
26	Moon at apogee.
29	Mercury greatest elongation W. (25 deg.)
30	Mars at aphelion.

Lunar Almanac for May 2023

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 19	Deep Space Objects
	1st. Qtr 27	Planets & Moon
	Full 05	Moon
	Last Qtr 12	Deep Space & Planets

Topic of the month: Venus adorns the Northern Sky

If you live in the northern hemisphere, no doubt you have noted the prominence of the bright planet Venus in the evening sky. Venus is the brightest natural object in the sky after the Sun and the Moon. This is because Venus is the closest planet in the solar system to Earth. Soon Venus will be crossing in front of the Sun (August 13, 2023) when it reaches the closest point to Earth. This crossing is called inferior conjunction and is faithfully reported in the monthly What's Up? almanac. At that time the sunlit side of our sister planet is facing away and Venus will not be seen.

During the current cycle of Venus, northern observers will find the planet among the stars on the northern side of the ecliptic. In May it shines in Taurus, crossing over into Gemini early in the month. On May 9, Venus is at greatest heliocentric lat. N. so that northern observers see it high over the horizon, setting after midnight. After this, our sister planet seems to stray even further away from the Sun. On June 4, Venus moves into the constellation of Cancer, joining the red planet Mars.

Venus reaches the maximum elongation East on June 4 when it is 45 deg. away from the Sun. On June 12, Venus will pass 0.6 deg. north of the open star cluster known as the "Beehive" or "M-44". It closes the distance between it and Mars until the beginning of July, when it stops and snaps like a yo-yo, returning to the Sun. Now it becomes more difficult for observers in the north and those in the southern hemisphere are able to see Venus rising higher in their sky. Venus reaches its greatest brilliancy for this apparition on July 7, shining at -4.7 magnitude.

On July 20, a nice grouping of three planets, Venus, Mars and Mercury will not be visible to those in the north as the evening twilight will be sadly too long. This is also the date of the first Venus standstill, and our sister planet will begin to move rapidly toward the Sun.

Venus opens August, shining at -4.2 mag., lost in the Sun, increasingly hard to find as it is less than 20 degrees away and closing fast. Venus starts out in Leo but soon heads back to Cancer, reaching inferior conjunction on August 13, 2023. At the time of inferior conjunction, Venus is 7.7 deg. south of the Sun's center. (This heliocentric position is used by astronomers to reckon many angles for objects in the solar system.) Sometimes Venus passes much closer to the Sun, actually transiting across the solar disk but this is not to occur again for many years. Now the cycle is complete and a new apparition of Venus begins when the first sighting of Venus Morningstar occurs just before sunrise.

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