Hi all,
1. IAA LECTURE SEASON: Opening Lecture, Wednesday 17 September, 7.30 p.m. Larmor Lecture Theatre, Physics Building, QUB
"Jewels of the JWST: How the Webb Telescope is Changing Our Understanding of the Universe" by Prof Tom Ray, DIAS.
Abstract: Since the James Webb Space Telescope has started operating it has challenged and enriched our understanding of how fast the Universe is expanding, how galaxies emerge earlier than we thought, and the diverse composition of planet forming disks. In this talk I will explain many of these exciting discoveries and the new synergies between the Webb and cutting-edge ground based telescopes.
BIOG: Prof Ray is one of Ireland's leading astronomers, with a very lengthy CV: He is Senior Professor of Astronomy at the Dublin Institute of Advanced Studies, and a Principal Investigator on the amazingly successful MIRI Instrument on the JWST.
We have been honoured to have many superb lectures from him before, so this is one not to be missed!
Admission free, including light refreshments. All welcome.
2, The Moon will occult Venus in daylight on 19 September.
Both are bright enough that the event will be readily visible, if the sky is clear, in binoculars or a telescope. The Moon will be approximately 39 degrees away from the Sun.
The Moon will be a thin waning crescent, 6% illuminated, (LQ on Sep 14 at 11h, NM on Sep 21 at 20h), so disappearance will be behind the bright limb of the. Moon, and reappearance from behind the dark limb, which probably won't be visible in the bright sky, so you'll have to estimate where it is. It's a fairly central occultation. Times will vary according to your location: the following details are for the START of the disappearance, and the START of the reappearance: since Venus is a disc, it won't be instantaneous: Venus will have an apparent diameter of about 12", and a phase of 89%.
Location Start of Dis. Start of Reapp. (Times in B/IST)
Belfast 12h 42m 36s 14h 01m 01s
Cork 12h 45m 37s 14h 02m 58s
Dublin 12h 44m 43s 14h 03m 58s
Galway 12h 42m 20s 13h 59m 50s
L/Derry 12h 40m 32s 13h 58m 48s
You could also look for Regulus (mag 1.3) ¼ degree (half lunar diameter), S of the S Cusp of the Moon before the Venus reappearance.
Be careful not to get the Sun in the field of view if you are sweeping the sky with binoculars!!!
3. SATURN AT OPPOSITION on Sep 21.:
The ringed wonder will reach opposition on Sep 21, at mag 0.6, apparent diameter 19.4".
Both the Sun and the Earth are now on the South side of the ring plane, but the rings present to us at a very narrow angle of just over 1 degree, and they will close even further as Saturn retrogrades, due to Earth's orbital motion.
On 30 Sep it will have faded slightly to mag 0.7, diameter 19.3"
4. Autumn Equinox, 22 September.
The Sun will cross the celestial equator southwards on Sep 22 at 18h 20m, marking the start of Autumn in the N. Hemisphere. But although the name 'equinox' means (day equal to) night. It's not as simple as that, for two reasons.
1. We define sunrise as when the upper limb (edge) of the Sun first appears above the E horizon, and sunset as when the upper limb disappears below the W horizon. Since the Sun is just over half a degree in diameter, that adds a minute or more to 'daylight'.
2. The effects of refraction by the Earth's atmosphere raise the Sun about half a degree above its actual position at both rising and setting, which adds another couple of minutes. In other words, when you first see the whole of the Sun coming up clear of the E horizon, almost the whole of the Sun is actually just below the horizon!
The actual date when daylight is exactly 12h long is therefore a couple of days later than Sep 22 – about Sep 25, depending on your location on Earth.
5. SUBSCRIPTIONS DUE, 1 September
After many many years of keeping the subs constant at £20 we have reluctantly had to raise the amount to £25, to cover rising costs. Student membership is only £10. Details on the IAA website https://irishastro.org/
Please amend your payment details accordingly. If you have already paid at the old rate, please add an extra £5 via Paypal or whatever is convenient.
6. INTERSTELLAR COMET, 3I/ATLAS
It's official! An interstellar object is visiting our solar system
With an absolute magnitude of about 12, it will be interesting to see how much it brightens as it nears perihelion. We may get our best view as it moves out from the solar glare in December, and gets closest to Earth, although even then it will be about 1.6 AU away.
LATEST – Here's A Photo Telescope spies rare interstellar comet 3I/ATLAS zooming through our solar system (photos)
The CBAT about 3I/ATLAS:
http://www.cbat.eps.harvard.edu/iau/cbet/005500/CBET005578.txt - it gives the comet as 13th magnitude after perihelion, in November with the elongation around 60°.
Please ignore all the media speculation about this being an alien artefact: just Avi Loeb off on his favourite hobby-horse again. - As Prof Chris Lintott told me recently 'It's nonsense on stilts!'
And NASA has just released the following NASA responds to claim that mystery space object is potential alien spacecraft
Since this is the first chance any of us will have had to see a non-stellar object from outside our solar system, I'm giving the following details for initial planning. No doubt more accurate details will be available in due course:
Epoch = 2025 Oct. 12.0 TT
T = 2025 Oct. 29.41062 TT Peri. = 127.93850
e = 6.1801697 Node = 322.18759 2000.0
q = 1.3620397 AU Incl. = 175.11382
(Note that the inclination is much more than 90 degrees – almost 180, in fact. This means that it is travelling round the Sun in almost the opposite direction to all the planets. Which also means that if it were to hit us, it would be quite a bang!)
The following ephemeris is from the above orbital elements, and uses photometric power-law parameters H = 9.5 and 2.5n = 8 for the magnitudes. (Delta is distance from Earth, and r (Radius Vector) is distance from the Sun, both in AUs). Elong is angular elongation from the Sun.
There are no figures from 22 Sep up to 21 November, when it will be too close to the Sun for easy observation. But perhaps more information will be obtainable closer to the 'Superior Conjunction' date, based on the latest observations.
I wonder who in Ireland will be first to image it? And I hope to be able to see it visually, although I no longer have my own 37cm reflector!
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2025 09 17 14 53.51 -12 35.0 2.542 2.059 50.8 22.2 14.0
2025 09 22 14 43.19 -11 59.1 2.531 1.928 43.3 20.9 13.8
2025 11 21 12 34.09 -02 22.3 2.040 1.593 49.8 28.3 12.7
2025 11 26 12 18.72 -01 01.8 1.978 1.694 58.9 29.9 12.8
2025 12 01 12 01.83 +00 27.9 1.920 1.808 68.4 30.5 13.0
2025 12 06 11 43.30 +02 06.8 1.871 1.932 78.4 30.0 13.1
2025 12 11 11 23.10 +03 54.3 1.833 2.063 88.8 28.5 13.3
2025 12 16 11 01.34 +05 48.4 1.811 2.202 99.7 26.1 13.5
2025 12 21 10 38.31 +07 45.8 1.808 2.345 110.8 23.1 13.7
2025 12 26 10 14.50 +09 42.1 1.828 2.493 122.1 19.5 14.0
2025 12 31 09 50.52 +11 32.4 1.872 2.645 133.3 15.7 14.2
2026 01 05 09 27.06 +13 12.7 1.941 2.799 144.3 11.8 14.5
2026 01 10 09 04.75 +14 40.1 2.035 2.956 155.0 8.1 14.8
2026 01 15 08 44.07 +15 53.7 2.153 3.114 165.1 4.6 15.1
2026 01 20 08 25.34 +16 53.8 2.293 3.274 174.5 1.7 15.4
2026 01 25 08 08.70 +17 41.8 2.454 3.436 175.2 1.4 15.7
2026 01 30 07 54.15 +18 19.6 2.632 3.599 167.0 3.5 16.1
7. ISS
The ISS continues its series of evening passes until 26 September. Details for your location are available on www,heavens-above.com There will be a very good pass commencing at 21.19, after our opening lecture meeting on 17 September. From Belfast, it will pass very close to Rasalhague (Alpha Oph), mag 2.1
8. VENUS and JUPITER VISIBLE IN MORNING SKY
Our sister planet is now visible low in morning twilight in Cancer, Jupiter is higher up in Gemini.
9. WhatsApp Group for alerts on Observing Nights.
The IAA have set up a WhatsApp Group for updates on Observing Nights. If you would like to be included in this group, please e-mail Mary at callistoboxers@hotmail.com with your full name & mobile telephone number.
No discussions about anything other than Observing Nights will be posted on this group.
10. WORLD SPACE WEEK, 4 – 10 October Irish events will be co-ordinated by BCO in Cork.
11. October 4: International Observe the Moon Night
12, 2025 Hamilton Lecture: 'My romance with the warped side of our universe' - Royal Irish Academy, 16 October, by Nobel Laureate Prof Kip Thorne,
13. ALAN 2025, 28 – 30 October 2025, Westport, Co.Mayo.
Preparations are nearly complete for the 9th Scientific Conference on Artificial Light At Night, ALAN2025, from October 28-30, 2025, in Westport, Ireland. Our host will be Dark Sky Ireland. The invited speakers will be revealed soon, but we can already promise you interesting talks about science, governance, dark sky outreach, and lighting design.
The conference offers a platform for interdisciplinary networking and exchange on the topics Biology & Ecology, Governance & Regulations, Health, Measurements & Modelling, Social Sciences & Humanities, Technology & Design.
We welcome researchers, lighting professionals, policy makers, light pollution activists, and everybody who is interested in the effects of artificial light at night. The conference aims to present new findings, exchange experiences and ideas, network, and discuss hoe artificial light can be used with less negative impacts.
I'm on the organising committee for this event, so I'll keep you posted regarding the programme.
For more information check out our website at artificiallightatnight.org .
This event will be followed immediately by the wonderful Mayo Dark Sky Festival in nearby Newport –
14. Mayo Dark Sky Festival, 31 October – 2 November. Another amazing programme, with a wide variety of events. One of the highlights of the year.. Details and tickets at https://www.mayodarkskyfestival.ie/?utm_campaign=756da2e1-b561-4d4d-9587-9fe4dd8cee87&utm_source=so&utm_medium=mail&cid=deca6829-6eef-4150-952e-f2ca19b05911
15. CAP May 2026, Armenia:
As the only large-scale international conference dedicated to astronomy communication, CAP gathers science communicators, educators, planetarium professionals, journalists, astronomers, and creatives to explore the best ways to share astronomy with diverse audiences. Whether you work in outreach, media, museums, or informal education, CAP is where you'll find inspiration, fresh perspectives, and a welcoming global community.
The next CAP Conference will happen in May 2026, hosted by the Byurakan Astrophysical Observatory and the Armenian Astronomical Society, in-person in Yerevan, Armenia, and online. This hybrid format ensures that participants from all corners of the world can take part in the discussions, workshops, and networking opportunities.
Organised by IAU Commission C2 and the IAU Office for Astronomy Outreach, CAP 2026 promises to be an unmissable event. If you're passionate about bridging the gap between science and society, this is your chance to connect, learn, and contribute to the future of astronomy communication.
16: 2026 Eclipse planning.
This may be of interest to those planning observing locations for the total solar eclipses in 2026 and 2027
Global risk map reveals the most dangerous countries and cities
And weather prospects for the coming eclipses such as the one in Spain in 2026, and N. Africa in 2027, are on www.eclipsophile.com . The discussions there will help you pick a site for the eclipse, as weather is one of the important factors to consider.
17: Recurrent Nova T Corona Borealis – We're still waiting!
It's well over a year now since the first predictions of an 'imminent' outburst! But, it could explode any time, so, keep an eye on it - comparison charts can be found on the websites of the BAA Variable Star Section, or the AAVSO. The current magnitude is around 10, so you'll need a good telescope to see it now.
(BTW, don't confuse it with the other nearby famous variable star, R CrB, which does the opposite – it stays normally around 6th magnitude, but occasionally dims to as faint as magnitude 14 or 15!)
Anyway, do keep an eye out – T CrB lies just outside the East side of the circle of the 'Crown', about a degree from Epsilon CrB, but you really do need charts to observe it properly. It's now visible in the sky each night.
It's at Declination: 25° 55′ 12.613″; R.A.: 15h 59m 30.1622s)
18: EASY TEASER: No correct answers!
What's next in this sequence – I've now added yet another one - What's next after Sirius:?
1. Aldebaran, 2. Rigel, 3. Capella, 4. Betelgeuse, 5. Sirius. 6…..,?
Clue: It's Right….
Final clue: what system to astronomers use to measure position in the sky?
NO CORRECT ANSWERS. I have defeated you. The answer is Procyon: They are the First mag stars visible from here in order of increasing Right Ascension. In case you don't know, R.A. is the system used by astronomers to define the position of an object on the celestial sphere; the celestial equivalent of Longitude. It's measured Eastwards from the 'First Point of Aries' (ask Wiki about that) along the celestial equator. It is measured in Hours, minutes and seconds of arc, with 24h = 360 degrees, (Computers now prefer decimals, but that's another story.
That also means that during the course of any day/night, that is the order in which those stars will cross the meridian.
19: NEW EASY TEASER:
What's the next (and last) one in this sequence A, A, D, M, M, M ?
20, DIFFICULT TEASER: - ANSWERED
Where in astronomy would you find the following sequence of letters (ignoring variable stars) - "Z Z"
Clue: Note the space between the letters.
Another clue: What's in a name?
One more clue: there are other letters involved, before the first one, and after the second one.
Final Clue: An astronomer.
WELL DONE to PETER DENMAN again! The answer is FRITZ ZWICKY, famed, brilliant and controversial astronomer / cosmologist, best known for being the first to propose the existence of dark matter.(Also well known for his brilliant physicist's description of some of his least favourite colleagues!)
I think Peter must now be the leader in the tally of first correct answers to teasers. Well done.
21. NEW DIFFICULT TEASER:
What is significant about the dates 3 April and 5 October, in 2025?
Remember, send answers to me only at my aol address: terrymosel@aol.com.
22. INTERESTING WEBLINKS (Disclaimer – Use of material herein from various sources does not imply approval or otherwise of the opinions, political or otherwise, of those sources). NB: If the title in the weblink does not indicate the subject matter, I give a brief simple intro before the link. I may also comment about the link afterwards.
ASTROPHYSICS:
Unusually long and repeating gamma-ray burst baffles astronomers - Earth.com https://share.google/pWXzeHFbh110WKgTb
AND Mysterious gamma-ray burst is unlike any detected before
Do 'black hole stars' solve a puzzle in the early universe?
James Webb telescope finds a warped 'Butterfly Star' shedding its chrysalis — Space photo of the week | Live Science
'This does not look right': Scientists accidentally measure ultrahot ring around black hole using rare 'double zoom' technique | Live Science https://share.google/gS852g4gkTmXboezV
A star stripped to its core: Astronomers discover an extraordinary supernova - Futura-Sciences https://share.google/iPKZITqfdIFSS3Rjz
Astronomers finally find elusive, dust-shrouded supermassive black holes at 'Cosmic Dawn' | Space https://share.google/LBsI9UPqx7cbWqGfL
First-ever complete measurement of a black-hole recoil achieved thanks to gravitational waves https://share.google/k6gedoVsAu72m34U4
Black Hole on X: "For the first time in human history, astronomers have captured the earliest stages of a solar system forming—a cosmic event that's been theorized for decades but never directly observed. Scientists focused on a young star named HOPS-315, located about 1,300 light-years away in https://t.co/R1iZM9uJq8" / X https://share.google/2ZBDJ4jJp9LeLDqo2
Cosmic giant poses problems https://search.app/jFv3Q
Small black holes are surprisingly messy eaters, Japanese spacecraft discovers: 'Being surprised is good' | Space https://share.google/IHYjSxK9RJ2q8Zg6f
COMET I3/ATLAS (I3 stands for 'Interstellar 3', i.e. the 3rd known interstellar object)
The Gemini South Telescope Takes A Turn Imaging The Interstellar Comet 3I/ATLAS - Universe Today https://share.google/xiWfB6wmIp4ye1PtL
Interstellar comet 3I/ATLAS could be turning bright green, surprising new photos reveal | Live Science
NASA responds to claim that mystery space object is potential alien spacecraft
Interstellar visitors like comet 3I/ATLAS are the most common objects in the Milky Way: 'There's almost always one within the solar system' | Space https://share.google/l2iTQKW2p1ISeq7w1
"That Star Is Shooting Jets Every Nine Hundred Years": Japanese Astronomers Capture Young Star Formation 26,000 Light Years Away https://share.google/hkaHHhHldHXlScJPq
James Webb Space Telescope images enormous star shooting out twin jets 8 light-years long | Spacehttps://share.google/oU0TXiqkvc8yMre8O
COSMOLOGYHow understanding nothingness might just explain everything | BBC Science Focus Magazine https://share.google/yUU7Vu3VYjawqdI1p Well, I understand nothing, so that's a good start!
EARTH & MOONNew 'quasi-moon' discovered in Earth orbit may have been hiding there for decades
EXOLIFE:NASA announces discovery of life on Mars with high confidence - Earth.com https://share.google/HOCp9SMe24UOshKV6 That headline is a bit of an exaggeration!
AND 'Incredibly exciting': NASA claims it's found the 'clearest sign' yet of past life on Mars | Live Science
AND Has NASA Detected Convincing Evidence Of Ancient Life On Mars? - Universe Today
Enceladus, The Life Signs That Weren't - Universe Today https://share.google/Qf6uOQDZsMUifivdk
EXOPLANETSExoplanet 40 light years from Earth may have right conditions for life | New Scientist https://share.google/jFKKuCfpui4qW12WK
JWST Finds An Exoplanet Around A Pulsar Whose Atmosphere Is All Carbon - Universe Today https://share.google/aDubDWWwyQE0D1W2k
Second exoplanet found orbiting nearby star Gliese 536 https://share.google/drvCG5FIoWiAgU3j3
IMAGESFrom 1-gigapixel images to 22-hour exposures – check out the winners of this inspiring astronomy photography competition
Astronomy Photographer of the Year https://share.google/GDaZgKK7hiqLm4MZM
A new version of this classic – well worth watching, as it's well annotated https://youtu.be/U9WOMerccoM?si=6YHSTrMcGKiCtCAj
LIGHT & SATELLITE SKY POLLUTIONA Defender of Darkness in the Darkest Place on Earth - The New York Times https://share.google/fuKb14o7NGMNDlfAz
SOLAR SYSTEM New comet SWAN25B is already bright, but near sun https://share.google/9Kni9jQTwg4v94zDH
On Oct. 18-21, Comet SWAN will be only 0.26 AU from our planet. If it doesn't fall apart between now and then, it could become a beautiful target for photographers and backyard astronomers. Another date of interest is Oct. 4-6 when Earth might cross the comet's debris streamA dwarf planet far beyond Pluto might have a paper-thin atmosphere | Mashable
NASA announces discovery of life on Mars with high confidence - Earth.com https://share.google/HOCp9SMe24UOshKV6 That headline is a bit of an exaggeration!
AND Did NASA's Perseverance rover actually find evidence of life on Mars? We need to bring its samples home to find out, scientists say | Space
AND NASA announces Mars rock as a potential biosignature
AND 'Incredibly exciting': NASA claims it's found the 'clearest sign' yet of past life on Mars | Live Science
Mars once had an atmosphere that was thicker than Earth's today | New Scientist https://share.google/en5pr7yos8mCTxnbc
Webb detects gases and activity on dwarf planet Makemake - Earth.com https://share.google/XkgQZUeY1TtJGksnK
Enceladus, The Life Signs That Weren't - Universe Today https://share.google/Qf6uOQDZsMUifivdk
Jupiter is smaller and more squashed than we thought | New Scientist https://share.google/cLMo0kqB359s6C8qZ
After early struggles, NASA's ambitious mission to Titan is "on track" for launch - Ars Technica https://share.google/dShzaZ48EKAXqfv4M
SPACEHumans could live on the moon by 2030 as scientists plan lunar base
British woman among crew training for Mars simulation mission
Artemis II is launching in early 2026. You coming with? Now you can. Submissions are open to fly your name around the Moon. Your name will be recorded on a memory card that will be stowed inside the Orion spacecraft. Sign up here: http://go.nasa.gov/artemisnames https://search.app/2qVxF
SUN
108 million degrees: Solar flares are far hotter than thought, study suggests | Space https://share.google/thhCGnDUdDxpZwarz
TELESCOPES, INSTRUMENTS, TECHNIQUES
A New Neutrino Detector In China Is Coming Online - Universe Today https://share.google/q3JkuJyzYysTeEPYk
ESA - Columbus: 100 000 orbits and counting https://share.google/9vnV4O7O9MhDhdJPn
The Murchison Widefield Array just doubled in size—what could it find now? https://share.google/rJUg7zl6znn2wEHVu
FINAL WORD:
"The treasures hidden in the heavens are so rich that the human mind shall never be lacking in fresh nourishment." - Johannes Kepler
23. JOINING the IRISH ASTRONOMICAL ASSOCIATION. This link gives options to join the IAA.
https://irishastro.org/join-the-iaa/ If you are a UK taxpayer, please select the 'gift-aid' box, as that enables us to reclaim the standard rate of tax on your subscription, at no cost to you. You can also make a donation via Paypal if you wish: just click on the 'Donate' button. See also https://irishastro.org/
The Irish Astronomical Association is registered with The Charity Commission for Northern Ireland NIC 105858
DISCLAIMER: Any views expressed herein are mine, and do not necessarily represent those of the IAA.
Clear skies,
Terry Moseley
