What's Up in the Night Sky

April 2025 - Vol. 29, No. 4

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 West, on the ecliptic, find the Gemini Twins, Castor and Pollux, and finally the Pleiades star cluster, an asterism of Taurus.

MERCURY rises in the morning twilight favoring observers in the southern hemisphere. VENUS, returning to the morning sky, will be closer to the horizon for northern observers this apparition. MARS is visible in the evening sky, starts the month at +0.4 magnitude and ends the month at +0.8 magnitude. JUPITER in Taurus, sets after midnight until late April, when it sets before midnight. SATURN emerges in the morning twilight, but will be hard to find as the Sun rises earlier and earlier. URANUS is heading toward solar conjunction and is low on the western horizon at sunset. NEPTUNE re-emerges from solar conjunction, quite low 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
01	Moon 0.6 deg. N of the Pleiades star cluster (M-45).
03	Jupiter 6 deg. S. of Moon.
05	Mars 2 deg. S. of Moon.
06	Mercury stationary.
10	Venus stationary.
13	This month's full Moon is often called the "Pink Moon" after a specific spring flower, phlox subulata, sometimes called "pink moss." Moon at apogee. Alpha Virginis, Spica, 0.3 deg. N. of Moon, occultation from Central America, most of South America, and S. tip of Africa.
16	Alpha Scorpii, Antares, 0.4 deg. N. of Moon, occultation from S. part of Africa, Kerguelen Is., E. Antarctica, and parts of Australia.
17	Mars at aphelion.
21	Mercury at greatest elongation W. (27 deg.)
22	Lyrid Meteor peak. The shower is estimated to contain 20 meteors at peak, this year the Moon is near last quarter.
25	Venus 2 deg. N. of Moon. Saturn 2 deg. S. of Moon.
26	Mercury 4 deg. S. of Moon.
27	Moon at perigee, expect large tides. Venus at greatest illuminated extent.
29	Moon 0.5 deg. N of the Pleiades star cluster (M-45). Venus 4 deg. N. of Saturn.
30	Jupiter 5 deg. S. of Moon.

Lunar Almanac for April 2025

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 27	Deep Space Objects
	1st. Qtr 05	Planets & Moon
	Full 13	Moon
	Last Qtr 21	Deep Space & Planets

Topic of the month: Messier Marathon

Amateur astronomers hold Messier Marathons every March. Basically, it is an attempt to see as many objects as possible in one night. The Messier objects were cataloged by Charles Messier so that he could avoid mistaking the brightest objects for the comets he was hunting. These objects are among the brightest in the sky, easily captured in amateur instruments. It is because of the length of the night and the locations of the various objects that make the time frame near the March equinox optimum for finding the largest number of objects possible.

The Messier objects are deep sky objects, rather than planetary objects. These objects may be open or globular star clusters, galaxies, even bright nebula. Star clusters are a little easier to spot. Galaxies and nebula are extended objects, this means their light is spread out over a small area of the sky. Because of this, their magnitude estimates are integrated. Light pollution is a killer, so a dark site is needed for success.

The Moon is a big factor for finding and seeing the fainter objects. Every third year, the marathon is blessed to occur near a New Moon. Other years the Moon may be near first or last quarter, but the Full Moon is devastating. For 2025, the New Moon is on the 29th so there are two "official" dates for the marathon, March 22 and March 29. On the 22nd, the last quarter moon will interfere with the observations in the morning sky. On the 29th, the length of night is a little shorter. It might not seem like much, but the first objects are setting in the evening twilight and the last objects are rising in the morning twilight. This is also a consideration when an observer is trying to see as many of them as they can.

Here are some resources available at Astra's to assist amateur astronomer's wishing to take up the Messier Marathon challenge:

Holding a Messier Marathon - advice from Astra

Messier Marathon Sequence - Use this list for your Marathon Observations

The Binocular Messier Catalog - the best Messier binocular objects

There are many resources on the internet that can help with your Messier Marathon in 2025. Local Astronomy clubs often hold marathons and they provide information from their specific locations. They may even have an observing site that you can access. As usual, Astra recommends hooking up with your local astronomy organization, especially if you are a beginner. The organization Students for the Exploration and Development of Space, commonly known as SEDS, maintain good webpages on Messier Marathons as well as many other subjects. See SEDS Messier Marathon 2025 for information on this year's event. I am wishing you clear sky, whatever night you attempt the marathon.

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