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

Compiled and written by Steve Sawyer

_{This month the images are being inspired by one of England’s most famous artists, John Constable. So we start with a noctilucent skies version of the Hay Wain. more info on the original can be found here.}

Welcome to June’s What’s up! I can’t believe we’re halfway through the year already!
We’re well into the lighter nights now, it can be hard to pick out even the brighter stars in the twilight skies of June. One of the compensations is to look out for noctilucent clouds (which I mentioned last month). June is one of the best months for spotting these so keep an eye out around midnight.

Here’s what’s up this month!

This Months York Astro Presentations

This month we can look forward to

06/06/2025 Members evening. Talks by our members
20/06/2025 Visual Astronomy: Alive and Kicking! by Simon Bennet

Other upcoming events

Upcoming events to put in your diary

Date	Title	Speaker
04/07/2025	Galaxies: Citizens of the Universe\|	Dave Armeson
18/07/2025	When Worlds Collide	Roy Gunson

For further details see the events page Astronomy Presentations by guest speakers | York Astro and our Facebook group (20+) The York Astronomical Society Chat Group | Facebook

So what’s on this month?

Despite the summer twilight, some southern sky sights are still visible. Libra lies due south, while the red supergiant Antares in Scorpius glows low in the southeast—though the Scorpion’s tail stays below the horizon. Above, the large constellation Ophiuchus sits between the two halves of Serpens (Caput to the west, Cauda to the east), with the Sun spending more time here than in neighbouring Scorpius. Higher still, Boötes, Corona Borealis, and Hercules are well placed—perfect for viewing the brilliant globular cluster M13.

Sky Diary

This table captures the astronomical events for June, including phases of the moon, planetary alignments, and other notable occurrences.

Date	Event
01	Venus reaches greatest western elongation (45.9°)
01	Mars (mag 1.2) appears 1.4° south of the Moon
02	Regulus is 1.8° south of the Moon
03	First Quarter Moon
06	Spica lies 0.5° north of the Moon
07	Moon reaches apogee (405,553 km)
10	Antares appears 0.3° north of the Moon
11	Full Moon
12	Venus reaches aphelion
17	Mars (mag 1.4) is 0.7° north of Regulus
18	Last Quarter Moon
19	Saturn (mag 1.0) is 3.4° south of the Moon
21	Summer Solstice
21	Mercury (mag -0.2) is 4.8° south of Pollux
23	Pleiades lies 0.6° south of the Moon
23	Moon reaches perigee (363,178 km)
25	Jupiter (mag -1.9) appears 5.1° south of the Moon
25	New Moon
26	Pollux lies 2.5° north of the Moon
27	Mercury (mag 0.1) is 2.9° south of the Moon
29	Regulus appears 1.5° south of the Moon
30	Mars (mag 1.4) is 0.2° south of the Moon

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.

Junes Objects

From Mays edition but it’s still relevant for the coming month!
Noctilucent cloud season is underway over the next few months, and I’ll try to post some forecasts here when I can.

Noctilucent clouds, also known as “night-shining” clouds, are high-altitude clouds that glow after sunset or before sunrise. They form around 80 km above Earth’s surface, where the atmosphere is extremely cold and thin. These clouds are composed of tiny ice crystals that catch the Sun’s rays, creating bright, ghostly displays.

In the Northern Hemisphere, noctilucent clouds typically appear between late May and mid-August, mainly between latitudes 50° and 70°. In the Southern Hemisphere, they are visible from late November to mid-February. To spot them, look low on the northern (or southern) horizon about an hour or two after sunset or just before sunrise, under clear, dark skies. Visibility can vary from faint, delicate wisps to striking, vibrant formations depending on conditions.

For more information, check out Noctilucent clouds – Met Office, and here’s a beautiful video capturing them:
Watch on YouTube

The Sun

🔭 Space Weather Outlook: May 26 – June 21, 2025

Data Source: NOAA SWPC

As we move into the early summer sky watching season, the Sun continues to show moderate levels of activity—good news for solar observers and aurora chasers alike. Here’s your detailed look at the coming month’s space weather, based on the latest 27-day forecast from NOAA’s Space Weather Prediction Centre (issued May 26, 2025).

☀️ Solar Activity: Moderate and Evolving

Solar activity is expected to trend downward through early June before picking up slightly mid-month. The 10.7 cm solar radio flux, a reliable proxy for solar ultraviolet emissions and sunspot activity, begins at 135 sfu on May 26 and dips to a low of 110 sfu by June 3–4. From there, it climbs modestly back to 125–130 sfu toward mid-June.

🔹 Expect visible sunspots and solar prominences on most days.
🔹 Ideal conditions for solar telescope observers and H-alpha imaging.

🌍 Geomagnetic Conditions: Storm Watch Mid-June

Most of the period will see quiet to unsettled geomagnetic conditions, with the planetary Kp index hovering around 2 to 4. However, models highlight June 13–14 as a window of heightened geomagnetic activity, with a possible minor G1-class geomagnetic storm on the cards:

📅 Date Range	Planetary A Index	Max Kp	Conditions
May 26–June 10	5–15	2–4	Quiet to Unsettled
June 10–12	12–15	4	Active spells possible
June 13–14	20–30	5	Minor Storm (Aurora!)
June 15–21	8–12	3–4	Unsettled to Quiet

🔹 Best chance for aurora viewing—especially in northern latitudes—comes around June 13–14.
🔹 Amateur radio users may experience interference or reduced HF propagation during this period.

📡 Observing Tips

Aurora Hunters: If you’re located in northern Europe, Canada, or the northern U.S., mark your calendars for mid-June. Stay alert for aurora alerts from space weather services.
Astrophotographers: Monitor sunspot regions for potential solar imaging opportunities, especially on days with stable atmospheric seeing.
Radio Operators: Expect generally stable conditions, except around geomagnetic storm periods (especially June 13–14).

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

June Lunar Calendar

Junes’s moon calendar from Sky View Café (skyviewcafe.com)
A full yearly lunar calendar can be found here :-

https://www.mooninfo.org/moon-phases/2025.html

🌙 Moon Positions & Events – June 2025

Date	Event	Moon Phase
01	Mars (mag 1.2) appears 1.4° south of the Moon	🌓 Waxing Crescent
02	Regulus is 1.8° south of the Moon	🌓 Waxing Crescent
03	First Quarter Moon	🌓 First Quarter
06	Spica lies 0.5° north of the Moon	🌔 Waxing Gibbous
07	Moon reaches apogee (405,553 km)	🌔 Waxing Gibbous
10	Antares appears 0.3° north of the Moon	🌕 Near Full Moon
11	Full Moon	🌕 Full Moon
18	Last Quarter Moon	🌗 Last Quarter
19	Saturn (mag 1.0) is 3.4° south of the Moon	🌗 Waning Crescent
23	Pleiades lies 0.6° south of the Moon	🌘 Waning Crescent
23	Moon reaches perigee (363,178 km)	🌘 Waning Crescent
25	Jupiter (mag -1.9) appears 5.1° south of the Moon	🌑 New Moon
25	New Moon	🌑 New Moon
26	Pollux lies 2.5° north of the Moon	🌒 Waxing Crescent
27	Mercury (mag 0.1) is 2.9° south of the Moon	🌒 Waxing Crescent
29	Regulus appears 1.5° south of the Moon	🌓 Waxing Crescent
30	Mars (mag 1.4) is 0.2° south of the Moon	🌓 Waxing Crescent

Moon Feature

June offers excellent opportunities to explore the Moon under high-altitude, shadow-rich lighting. Ideal for revealing surface detail.
Here are three lunar features, timed to both the waxing and waning phases.

🌒 Early June 2–5* The Apennine Mountains & Mare Imbrium

📅 Best dates: June 2–5 (Waxing Crescent to Gibbous)
🕰️ Best time: Evening (8 PM–11 PM local time)
📍 Hemisphere: Northern lunar hemisphere

One of the lunar highlights, the Apennine Mountains (Montes Apenninus) form the southern arc of Mare Imbrium, the Sea of Rains. This rugged, curved range contains peaks rising over 5,000 meters and was the landing site of Apollo 15. Nearby, you’ll find:

Crater Archimedes – smooth floor, steep walls
Crater Aristillus – central peaks and ray system
The Straight Wall (Rupes Recta) – best seen around June 5 for dramatic contrast

🌓 Mid-June 10–13 Tycho & the Southern Highlands

🔭 Feature: Tycho & the Southern Highlands
🌕 Phase: Waxing Gibbous to Full Moon
🕘 Best time: Evenings, 10 PM onward

As the Moon approaches full (June 11), the southern highlands and Tycho Crater come into sharp relief. Tycho’s distinct central peak and surrounding ray system (bright streaks radiating outward) are especially eye-catching. Nearby craters Clavius and Longomontanus add complexity to this ancient landscape.

🌘 Late June 19–23 Schiller & the Southwest Limb

🔭 Feature: Schiller & the Southwest Limb
🌗 Phase: Waning Gibbous to Crescent
🕓 Best time: Pre-dawn, 3–5 AM

As the Moon wanes and rises later, switch to early morning observing. Catch the oddly-shaped Schiller Crater, along with rugged southern terrain. At this low Sun angle, long shadows stretch across crater walls.

Planets

Not a great deal to spot this month I’m afraid.

☀️ Mercury

Not well placed at the start of the month. but becoming a better target for observation after the middle of the month.

🟡 Venus

Although low on the horizon Venus is a bright morning object rising before the Sun in the eastern sky. Shining at a magnitude of around −4

🔴 Mars

Mars an be found in Leo and is visible in the evening sky. Setting earlier as the month progresses

🟠 Jupiter

Setting shortly after the sun, so very hard to see in the bright skies

🪐 Saturn

Morning planet and mainly lost in the suns glare,

🔵 Uranus

Not visible this month

🔷 Neptune

Not really a viable object to view this month

Meteor Showers

June Bootids

Peak Date: June 27
Radiant: Near the constellation Boötes
ZHR (Zenithal Hourly Rate): Variable, historically between 0-100 meteors per hour
Visibility: Best viewed after midnight
Description: The June Bootids are known for their unpredictability. While they have produced strong displays in the past, they can also be very weak. The shower’s activity can vary greatly from year to year. If there is an outburst, it can be quite a treat for observers.

Comets

Comet Name	Approx. Magnitude	Best Viewing Time	Visibility Notes
C/2023 A3 (Tsuchinshan–ATLAS)	+13	Evening twilight	Fading post-perihelion; visible low in the west-northwest.

Link here for further details of each comet and how to locate it.
Visual Comets in the Future (Northern Hemisphere) (aerith.net)

Deep Sky (DSO’s)

M13: The Great Hercules Cluster

This month we’ll have a deep dive on/into M13.

By Chuck Ayoub – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=163946870

M13 is located high in the summer sky, within the Keystone asterism of Hercules. This globular cluster spans about 145 light-years across and appears as a faint glow to the naked eye under dark skies. Through a modest telescope, M13 resolves into a dense ball of stars, with estimates of between 300,000 and 500,000 stars in total. The brightest star in the cluster is a red giant variable, V11, also known as V1554 Herculis.
M13 is 22,200 to 25,000 light years from Earth and is one of over a hundred globular clusters that orbit the centre of the milky way.

M13 was first noted in 1714 by Edmond Halley (of comet fame) and later catalogued by Charles Messier in 1764 as the 13th entry in his famous list of deep-sky objects. In 1779, William Herschel’s more powerful telescope transformed M13 from a “nebula” into a breathtaking swarm of stars, showcasing the true beauty of a globular cluster.

I did wonder if Chinese or other historical astronomers might have noted M13 in their observations as Ancient Chinese, Babylonian, or Greek astronomers often recorded bright celestial objects. But globular clusters like M13 were not commonly documented because they appear as faint, fuzzy patches rather than distinct stars or planets and were thought to be celestial vapours or cosmic clouds.

In 1974, M13 was selected as the target for the Arecibo message—a brief radio broadcast sent into space from the Arecibo radio telescope in Puerto Rico. The message, consisting of 1,679 binary digits, was intended as a symbolic demonstration of humanity’s technological capabilities and included basic information about our solar system, the human species, and our numbering system. Although the signal is expected to take around 22,000 years to reach M13 and another 22,000 years for any reply to return, I wonder if anyone will be around to listen for a reply!

Throughout June, M13 rides high in the south after nightfall, a jewel of the summer sky. Grab a pair of binoculars or a telescope and treat yourself to a direct encounter with one of the oldest, most spectacular structures in our galaxy.