A monthly look at astronomical events in the sky and on Earth

Compiled by Steve Sawyer

Well, it’s May already, how did that happen? I’m hoping for a few warmer days and some clear skies (with a little less rain!).

So what’s on this month?

Over the northern horizon, Cassiopeia appears low, with the southern areas of Perseus and Auriga fading into obscurity, although the Double Cluster nestled between them remains a vivid sight. Unfortunately, the Andromeda Galaxy dips too low to be easily spotted.

Prominently positioned are the constellations of Lyra, Cepheus, Ursa Minor, and all of Draco, Towards the west, Gemini and its notable stars, Castor and Pollux, descend toward the horizon, yet Capella and the asterism of The Kids still stand clear above it. In the eastern sky, Vega and Deneb—two vertices of the ‘Summer Triangle’—shine brightly, with Altair soon to rise, marking the triangle’s completion. The entirety of Cygnus spreads across the sky, and Hercules ascends high in the east, where the northern hemisphere’s brightest globular cluster, M13, is visible within the Keystone.

In the northeastern quadrant, the zigzagging Lacerta, along with Camelopardalis and Lynx to the west, are discernible before the approaching summer nights obscure them. As the night progresses, the westernmost stars of Pegasus emerge, and Andromeda’s stars skim the northeastern horizon, potentially offering glimpses of the Andromeda Galaxy. High above, Alkaid crowns the zenith, with the bulk of Ursa Major rotating westward.

In the South the early night sky is dominated by Virgo to the south, featuring Spica, with Leo and its bright stars Regulus and Denebola nearby. As the night deepens, Libra and Antares ascend.

Arcturus can be found in in Boötes, high in the southern sky, neighboured by the distinct circlet of Corona Borealis with its brightest star, Alphecca.

Sky Diary

Date and Time (UTC)	Event Description
01 11:27	Last Quarter
03 22:32	Saturn (mag. 1.2) 0.8ºN of the Moon
04 18:55	Neptune (mag. 7.9) 0.3ºN of the Moon
05 02:25	Mars (mag. 1.0) 0.2ºS of the Moon
05 22:04	Moon at perigee = 363,163 km
06	η-Aquariid meteor shower maximum
06 08:25	Mercury (mag. 0.6) 3.8ºS of the Moon
07 16:03	Venus (mag. -3.9) 3.5ºS of the Moon
08 03:22	New Moon
08 12:51	Uranus (mag. 5.8) 3.6ºS of the Moon
08 18:14	Jupiter (mag. -2.0) 4.3ºS of the Moon
09 18:54	Aldebaran 9.9ºS of the Moon
09 21:29	Mercury at greatest elongation (26.4ºW, mag. 0.4)
12 22:54	Pollux 1.6ºN of the Moon
15 11:48	First Quarter
15 19:24	Regulus 3.5ºS of the Moon
17 18:59	Moon at apogee = 404,640 km
19 15:06	Minor planet (2) Pallas at opposition (mag. 9.0)
20 10:03	Spica 1.4ºS of the Moon
23 13:53	Full Moon
24 03:10	Antares 0.4ºS of the Moon
30 17:13	Last Quarter
31 01:00	Uranus (mag. 5.8) 1.4ºN of Mercury (mag. -0.7)
31 08:09	Saturn (mag. 1.2) 0.4ºN of the Moon

This table organizes the celestial events by date and time, listing each event’s details for easy reference.
This table captures the astronomical events for April, including phases of the moon, planetary alignments, and other notable occurrences.

Sky Maps

Looking South on the 15th at 22:00

Looking North on the 15th at 22:00

The two charts above show all DSOs of magnitude 6.0 or brighter. They are both taken from
SkyViewCafe.com and correct for the 15th of the month. For a clickable list of Messier objects with images, use the Wikipedia link.

Mays Objects

The Sun

Currently active sunspot AR3654 is emitting M-class solar flares. The eruptions, directed towards Earth, are leading to shortwave radio blackouts at frequencies below 20 MHz. The latest flare, classified as M3, occurred at 0111 UT and disrupted shortwave communications across much of the Pacific Ocean.

As you can see from the graph above we’re approaching the current solar maximum but if you look at the smaller graph below which covers many solar cycles you can see we’re not anywhere near the level of activity that occurred in the 1950s.

Resources

For more info on the sun and solar weather look here : –

Space Weather Enthusiasts Dashboard | NOAA / NWS Space Weather Prediction Center

Auroa Forecasts

A bit US centred but still useful

Aurora Dashboard (Experimental) | NOAA / NWS Space Weather Prediction Center

And our own Met-office have an excellent space weather forecast page here Space Weather – Met Office

The Moon

May’s moon calendar from Sky View Café (skyviewcafe.com)

The Anglo-Saxon name for May’s full moon is the “Milk Moon.” This name, like many traditional names for full moons, comes from the natural and agricultural practices observed during this time of the year. May is traditionally a month when cows, goats, and sheep begin to produce more milk, thanks to the renewed abundance of grass and other forage, reflecting a time of fertility and new growth.

Another term sometimes associated with the May full moon in Anglo-Saxon culture is the “Flower Moon,” reflecting the widespread blooming of flowers during this period. This is more of a general term that aligns with what many Native American tribes have also historically observed about the season.

The Lunar Swirls (Reiner Gamma)

This month we’re not looking at a crater but a magnetic feature on the lunar surface.
The Lunar Swirls are are enigmatic high-albedo markings on the Moon’s surface. One of the most prominent being Reiner Gamma.

“Lunar swirls have long defied easy explanation, but recent modeling and spacecraft data shed light on the origin of these swirls – crustal magnetism. Think of lunar swirls as the Moon’s tan lines. Solar radiation bombards the Moon, but pockets of magnetic anomalies act as a sunscreen, shielding the brighter parts of the lunar surface from solar radiation and ‘sunburn.’ The magnetic ‘sunscreen’ redirects solar wind particles to areas just around magnetic bubbles, where chemical reactions darken the surface. This creates the distinctive swirls of darker and lighter material that are so prominent they can be seen from Earth.”

Quoted from Lunar Swirl Reiner Gamma – NASA Science

Location and How to Find Reiner Gamma on the Lunar Surface

Location: Reiner Gamma is located in the Oceanus Procellarum, or Ocean of Storms, on the Moon’s near side.

Coordinates: Approximately 7.5° N latitude and 59.0° W longitude.

Finding Reiner Gamma:

Identify the Mare: Start by locating the vast, dark plains of the Oceanus Procellarum on the western part of the Moon’s near side. This mare is one of the most extensive on the Moon, making it relatively easy to find.
Zoom in: Using a moderate to high-power telescope, focus in on the northwestern part of Oceanus Procellarum.
Spot the Swirl: Look for a distinctive swirling pattern of brighter material, which stands out against the darker lunar mare. Reiner Gamma itself is quite striking due to its unique shape and high reflectivity.

The best time to observe Reiner Gamma is just after the first quarter moon. During this phase, the angle of sunlight illuminates the feature from the side, enhancing its contrast against the surrounding lunar mare and making the swirl patterns more distinct. This typically occurs about 7-10 days after the new moon each month.

See the sky diary for this months lunar events as there are some nice viewing opportunities .

A full yearly lunar calendar can be found here :-

https://www.mooninfo.org/moon-phases/2023.html

Planets

A bit of a poor show this month!

Mercury

Not really visible this month, lost n the morning twilight

Venus

Not visible this month

Mars

Lost in the morning twilight

Jupiter

Can’t be seen this month

Saturn

Best of the planets this month, but still not great and is best towards the end of them month

Uranus

Not visible

Neptune

Not visible

Meteor Showers

This month it’s the turn of the….

Eta Aquariids

The Eta Aquariid meteor shower, one of the two meteor showers linked to Comet Halley (the other being the Orionids in late October), reaches its peak activity around May 5-6. The best viewing in the UK is expected just before dawn on May 6. This shower typically offers a moderate hourly rate of 40 meteors per hour, which is the theoretical number of meteors one might see under perfect conditions with the shower radiant—the point in the sky from which meteors appear to originate—directly overhead.

However, ideal conditions are hard to come by, and it’s rare for the radiant to be directly overhead. This is particularly true for the Eta Aquariids, where the radiant only just rises before the dawn begins, limiting the effective observation time and reducing the actual number of visible meteors per hour.

Despite these less-than-ideal circumstances, the viewing conditions this year are quite favourable due to the Moon being nearly out of the way, presenting a 5%-lit waning crescent which rises around 04:45 BST (03:45 UT). While a low radiant diminishes the number of meteors seen, it can also create spectacular displays of “Earth-grazers”—meteors that streak across the sky at a shallow angle, appearing to graze the Earth’s atmosphere.

If conditions are clear on May 6, it’s recommended to begin watching from 02:00 BST (01:00 UT) until dawn begins.

Comets

May’s comets. Go here for detailed locations and finder charts Visual Comets in the Future (Northern Hemisphere) (aerith.net)

Month	Time of Day	Comet	Magnitude (Mag)	Altitude (h)
2024 May	Evening	13P/Olbers	8	12
		C/2023 A3 (Tsuchinshan-ATLAS)	9	56
		479P/2023 WM26 (Elenin)	10	31
		C/2021 S3 (PanSTARRS)	11	20
		C/2023 V4 (Camarasa-Duszanowicz)	12	6
		C/2022 E2 (ATLAS)	12	39
		144P/Kushida	13	51
		C/2021 G2 (ATLAS)	13	26
		C/2022 L2 (ATLAS)	13	22
		29P/Schwassmann-Wachmann 1	13	51
2024 May	Midnight	C/2023 A3 (Tsuchinshan-ATLAS)	9	55
		C/2021 S3 (PanSTARRS)	10	44
		144P/Kushida	13	8
		C/2021 G2 (ATLAS)	13	14
		C/2022 L2 (ATLAS)	13	3
		29P/Schwassmann-Wachmann 1	13	7
2024 May	Morning	C/2023 A3 (Tsuchinshan-ATLAS)	9	14
		C/2021 S3 (PanSTARRS)	10	67
		154P/Brewington	11	4

Deep Sky (DSO’s)

NGC 891 – This edge-on spiral galaxy in the constellation Andromeda offers a distinct profile akin to the Milky Way as seen from Earth. It is about 30 million light-years away and showcases a dark dust lane bisecting its bright core.
NGC 4565 (The Needle Galaxy) – Also an edge-on spiral galaxy, located in the constellation Coma Berenices. It’s known for its thin, needle-like profile against the sky.
IC 1396 – An open star cluster enveloped by an emission nebula in the constellation Cepheus, often referred to as the Elephant’s Trunk Nebula due to its distinctive shape. This region is active with new star formation and has complex gas and dust structures.
Sh2-155 (The Cave Nebula) – A dim and diffuse bright nebula within a larger nebula complex containing emission, reflection, and dark nebulae. Located in Cepheus.
Abell 21 (The Medusa Nebula) – A planetary nebula in the constellation Gemini. It’s a challenge to observe due to its faintness and large size, but it’s a rewarding sight under good conditions.
The Intergalactic Wanderer (NGC 2419) – A globular cluster in Lynx, lying far away from the galactic plane, earning its nickname due to its isolated position. It’s one of the most distant globular clusters associated with the Milky Way.

ISS and other orbiting bits

ISS York overpasses for the beginning of May

Date	Visible	Max Height	Appears	Disappears
Wed May 1, 2:04 AM	< 1 min	10°	10° above ESE	10° above ESE
Wed May 1, 3:36 AM	5 min	41°	26° above SW	10° above E
Thu May 2, 2:49 AM	3 min	32°	32° above SSE	10° above E
Thu May 2, 4:22 AM	7 min	58°	10° above WSW	10° above E
Fri May 3, 2:01 AM	1 min	17°	17° above ESE	10° above E
Fri May 3, 3:34 AM	5 min	54°	24° above WSW	10° above E
Sat May 4, 2:46 AM	3 min	47°	46° above S	10° above E
Sat May 4, 4:20 AM	7 min	55°	10° above W	10° above ESE
Sun May 5, 1:59 AM	2 min	27°	27° above ESE	10° above E
Sun May 5, 3:31 AM	6 min	58°	16° above WSW	10° above ESE
Mon May 6, 1:11 AM	< 1 min	11°	11° above E	10° above E
Mon May 6, 2:43 AM	4 min	57°	37° above SW	10° above E
Mon May 6, 4:18 AM	6 min	42°	10° above W	10° above SE
Tue May 7, 1:56 AM	3 min	46°	46° above SE	10° above E
Tue May 7, 3:29 AM	6 min	50°	12° above W	10° above ESE
Wed May 8, 1:08 AM	1 min	20°	20° above E	10° above E
Wed May 8, 2:41 AM	5 min	56°	27° above WSW	10° above ESE
Wed May 8, 4:16 AM	6 min	28°	10° above W	10° above SE
Thu May 9, 1:53 AM	3 min	58°	58° above S	10° above E
Thu May 9, 3:26 AM	6 min	36°	10° above W	10° above SE
Fri May 10, 1:05 AM	2 min	24°	24° above ESE	10° above E
Fri May 10, 2:38 AM	5 min	45°	20° above W	10° above ESE
Fri May 10, 4:13 AM	4 min	17°	10° above WSW	10° above S
Fri May 10, 10:35 PM	4 min	21°	10° above SSW	17° above ESE
Sat May 11, 12:10 AM	2 min	23°	10° above WSW	23° above SW
Sat May 11, 1:50 AM	3 min	50°	50° above S	10° above ESE
Sat May 11, 3:24 AM	5 min	23°	10° above W