What's Up in the Night Sky

May 2025 - Vol. 29, 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, in the morning sky, favors observers in the southern hemisphere. VENUS, also in the morning sky, favors southern observers. MARS is visible in the evening sky, starts the month at +0.9 magnitude and ends the month at +1.2 magnitude. JUPITER in Taurus, sinks in the evening twilight. SATURN in the morning sky, wanders from Aquarius into Pisces. URANUS is in solar conjunction on the 17th and won't be observable this month. NEPTUNE is in the morning 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	Vesta at opposition.
03	Mars 2 deg. S. of Moon.
04	Venus 2 deg. N. of Neptune
05	Mars 0.4 deg. N of the Beehive star cluster (M-44). Alpha Leonis, Regulus 2 deg. S. of Moon.
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. This year's shower occurs during the waxing gibbous moon.
08	Mercury at greatest heliocentric lat S.
10	Alpha Virginis, Spica, 0.4 deg. N. of Moon, occultation from Micronesia, Melanesia, SW Polynesia, tip of Antarctic Peninsula, tip of S. America.
11	Moon at apogee.
12	This month's full Moon is often called the "Flower Moon" after the flowers that bloom in the season of Spring in North America.
14	Alpha Scorpii, Antares, 0.3 deg. N. of Moon, occultation from eastern Polynesia, S. South America, tip of Antarctica Peninsula, and SE edge of Africa.
17	Uranus in conjunction with the Sun.
22	Saturn 3 deg. S. of Moon. Neptune 2 deg. S. of Moon.
24	Venus 4 deg. S. of Moon.
26	Moon at perigee.
28	Jupiter 5 deg. S. of Moon.
30	Mercury in superior conjunction.

Lunar Almanac for May 2025

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 26	Deep Space Objects
	1st. Qtr 04	Planets & Moon
	Full 12	Moon
	Last Qtr 20	Deep Space & Planets

Topic of the month: Boötes and Corona Borealis

As night falls in the Spring sky a bright northern star appears in the East. Truly the brightest star in the northern sky, Arcturus boasts of −0.05 magnitude. Throughout the evening, Arcturus marches prominently across the sky. Its home is the constellation of Boötes, a kite-shaped constellation, referred to as "The Herdsman" or sometimes "The Plowman". Stargazers can find it by following the "arc" of the stars on the handle of "The Big Dipper" by the memorable instructions, "arc to Arcturus."

Arcturus and Boötes have colorful history. The name Boötes comes from the Greek word for herdsman. This is an ancient name for the constellation as later skywatchers also called the constellation, the "bear watcher", no doubt because it is close to the constellation Ursa Major (the Great Bear.) There are few interesting astronomical objects in this area because the constellation is far from the plane of the Milky Way galaxy. A small globular cluster, NGC 5466 can be found in the constellation, shining at 9.7 magnitude.

Another nearby constellation is Corona Borealis, also known as the "northern crown." The brightest jewel in the northern crown is the second magnitude star, Alphecca. Alphecca is the alpha star of the constellation and is also known by another name, Gemma. Alphecca has a magnitude of 2.2. A semi-circle of seven stars form a small crown-shaped constellation. It is fairly easy to spot from a dark site.

The Herdsman and the Crown — Corona Borealis and Boötes

finder chart for T Corona Borealis — T Corona Borealis Finder Chart

Corona Borealis has attracted astronomers' attention recently, as a recurrent variable star exists in this constellation. The star, T Corona Borealis is expected to brighten suddenly, up to magnitude 2.0. Although it was thought the star would erupt before September 2024, but that hasn't happened yet. Popularly called, "T Cor Bor", it's normally about 10th magnitude. Because of these outbursts, the star is known as the "Blaze Star"

In July of 2024, Astra's Stargate monthly topic covered the Blaze Star. That article includes a large finder chart and more information. Go to the article The Blaze Star, Awaiting the Outburst of T Coronae Borealis by following the link. Even from the city, a pair of binoculars can be used to discover whether or not the nova has occurred. When the news of its nova spreads over the internet, make sure you look quickly because it will only shine bright enough to be seen by the naked eye a short time.

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

The star chart above was generated by Stellarium, a free open source planetarium program. The above image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. Editing was done for educational purposes only. Stellarium offers much more to amateur astronomers and is being used in planetariums and to guide telescopes in the field. Simple charts like the one above can be used on the internet for non-profit, illustration purposes. Proper credit is due of course! Thank you to the makers of this fine program from Astra's Star Gate.