#bskycometography no. 351 C/1577 V1 1577 Nov 2: First seen from Peru at maybe -7 mag! Quickly seen world-wide. Perihelion on Oct 27 at 0.18 au, perigee on Nov 10 at 0.62 au. Used to prove for the first time that comets are outside of Earth's atmosphere. Last seen on 1578 Jan 26. ☄️🔭 #CometWatch

We already recovered it with the Lowell Discovery Telescope this morning: cometary.org/@qicheng/sta...

Against all odds, C/2025 K1 (ATLAS) has survived perihelion, which was at Mercury's orbit. The comet has emerged in the dawn sky and features a long ion tail, more than a degree long, with a distinct reddish color (contrary to the usual blue). #CometWatch

Michael Jäger does Michael Jäger things: C/2025 A6 (Lemmon) on Oct 26. forum.vdsastro.de/viewtopic.ph... which also has an animation. 🔭☄️

In the following paragraph of the same book, it says: And in the year 303 AH, in the month of al-Muḥarram, a star appeared with a tail — its head toward the west and its tail toward the east. It was extremely large, and its tail was widely spread. It remained for thirteen days until it vanished. 1/2

In the book Husn al-Muḥāḍarah fī Tārīkh Miṣr wa-al-Qāhirah, the author says: “In the year 313 AH, at the end of the month of al-Muḥarram, a star fell from the south toward the north before sunset, and the whole world was illuminated by it, and a sound like intense thunder was heard.” 1/2

#bskycometography no. 343 C/1639 U1 1639 Oct 25: Seen only over three days and recorded from Korea, China and Italy. Close perigee on Oct 26 at only 0.08 au while exhibiting a "fluffy shape"! The comet was not very bright but rather large, typical for comets close to Earth. ☄️🔭 #CometWatch

Comet C/2025 A6 with my smartphone today .

Wir haben einen dritten Fernglaskometen! Im Rahmen der letzten Beobachtungen vor dem Perihel im September wurde spekuliert, ob C/2025 K1 (ATLAS) den Durchgang durch den sonnennächsten Punkt überstehen wird und wir haben Glück, er ist gesund und munter! 1/3

18/10/2025 20:00 UT Comet C/2025 A6 Lemmon ( mag : +4.5 ) with 10×50 Binoculars and my smartphone . ISO: 3200- 1600 S: 10 s 40 images stacked using Sequator

Even with smoke on the horizon, the comet is still easily visible through 10×50 binoculars , and possibly just visible to the naked eye, though with great difficulty.

New paper on the climate and habitability of Tergarden’s star b, led by Ryan Boukrouche and ft. Me! This planet is a promising target for characterisation by next generation observatories such as LIFE. Take a peak to see what we found out…. (or just read the title 🙃) arxiv.org/abs/2510.11940

SOLAR ECLIPSE OBSERVED FROM SPACE: This could be a first. On Sept. 21st, NOAA's CCOR-1 coronagraph onboard GOES-19 observed a solar eclipse from Earth orbit. Watch the lights go out as the Moon zig zags between the satellite and the sun spaceweather.com/images2025/2... spaceweather.com

Spectacular ☄️ Lemmon "Comet Lemmon will be spectacular. If we can already see it now, what will it be like in October? C/2025 A6 Lemmon 2025-09-21 2.40 UT 11" RASA Asi 294m mosaic 9/9min Michael Jäger, Gerald Rhemann" Source Michael Jäger x.com/Komet123Jage...

Hi all, Today I observed comet C/2025 A6 (Lemmon) visually for the first time with 10×50 binoculars. The comet appeared moderately condensed with a fairly noticeable coma: 2025 Sept. 19, 04:02 UT: m1 = 7.5, Dia. ≈ 4′, DC = 5, 10×50 B, sky ~Bortle 3 (Moroccan desert). Clear skies, Amine Hamidi

Light curve of the new comet C/2025 R2 (SWAN) ☄️ According to it, the comet will stay between magnitude 7 and 6, observable with binoculars 👀, until its closest approach to Earth 🌍 at the end of October. More info here 👇 ℹ️ cometografia.es/cometas-visi... #astronomy #comet #swan #cometwatch

Darker skies, meant I could get a much deeper image of the new comet. This is a 5 x 5 degree crop. Sep 14 9hrs UT.

A new study led by ETH Zurich fellow @aaffholder.bsky.social examines whether Titan's subsurface ocean could support life. His findings suggest that if life exists there, it may persist only in extremely small amounts, making detection a formidable challenge. 🧪 🔭 Learn more:

A rather bright comet has been discovered in images of the spacecrafts SOHO/SWAN & STEREO - preliminary designated SWAN25B. It's 7-8 mag and w/ a nice tail. No orbit yet, but from the available data I suspect it could pass very close to Earth soon. Image by M. Mattiazzo, groups.io/g/comets-ml/... 🔭☄️

New bright SWAN comet SWAN25B on PCCP page !! www.projectpluto.com/neocp2/mpecs...

Interestingly, the new object in PCCP "P22ex9m" is expected to pass between Earth and the Sun in late April 2026. There is a chance it may appear to transit the Sun, similar to what the Great Comet of 1819 did, BUT that is not confirmed until its orbit is better determined.

Comet 3I/ATLAS 2025 Sep. 10.02 UT m1=13.9 (m2=15.3) Dia.=1.6' Tail=1.9' in PA 104 deg... [T72] 0.51-m f/6.8 Corrected Dall-Kirkham + CCD... T. Prystavski... (iTelescope observatory, X07 (remotely from Rio Hurtado Valley, Chile))

After nearly a decade of saying which JWST result I was most excited about, it's here: JWST SPECTRA OF THE HABITABLE TRAPPIST-1 PLANETS! TRAPPIST-1 E!!! IT'S ... A FLAT LINE! BUT NOT AS FLAT AS IT COULD BE!? IS THERE AN ATMOSPHERE?!?!? WE STILL DON'T KNOWWWWW. www.nytimes.com/2025/09/08/s...

Whoa, the interstellar comet 3I/ATLAS clearly has a tail now! A raw image taken minutes ago with the GMOS instrument on Gemini South and shared live during the Shadow the Scientists event - I raised the contrast slightly.

JWST successfully observed interstellar object (ISO) 3I/ATLAS. Interesting results. The composition of the coma could be due to a few different scenarios. Additional JWST observations of the object closer to the sun are needed. science.nasa.gov/blogs/3iatla...

#bskycometography no. 279 C/2001 Q4 (NEAT) 2001 Aug 24: Discovered by the NEAT survey at 17.5 mag. The comet reached a 3 mag at perihelion, which occurred not before 2004 May 15 at 0.97 au! The comet displayed a very impressive system of tails. It was last seen on 2006 Aug 18. ☄️🔭 #CometWatch

Comet C/2025 A6 (Lemmon) is much brighter than current predictions (maybe around mag 13) and even visible in the individual 20s frames today before dawn. Hopefully it will be a nice binocular object in autumn. #cometwatch

Fireball lights up sky over western Japan #Science #Space #Astronomy #Fireball #Japan #AstronomyNews

Rufous Tailed Scrub Robin 🇲🇦

Volatile time! As anticipated for a comet ☄️, interstellar object 3I/ATLAS is now showing water - thanks to OH emission seen by Swift in the UV. A little distant at 3.51 au, but that suggests it could be from water ice grains in the coma. Xing et al., ApJL submitted 🔭 arxiv.org/abs/2508.04675

Today on the #arXiv: Santana-Ros et al. 2025, "Temporal Evolution of the Third Interstellar Comet 3I/ATLAS: Spin, Color, Spectra and Dust Activity" - arxiv.org/abs/2508.00808 The nucleus of #3I/ATLAS remains confused with the coma.

Greater Flamingos 🇲🇦 #Birds 🇲🇦

#bskycometography no. 258 C/1729 P1 1729 Aug 1: Discovered by father N. Sarrabat (France) at 4.5 mag as a nebulous star. It moved very slowly and was observed until 1730 Jan 21. The comet had a far perihelion at 4.1 au on 1729 Jun 16. Absolute magnitude -3, a very large object. ☄️🔭 #CometWatch

Comet 240P/NEAT 2025 Jul. 07.40 UT m1=13.8 (m2=15.1) Dia.=0.5' Tail=1.9' in PA 236 deg... [T72] 0.51-m f/6.8 Corrected Dall-Kirkham + CCD... T. Prystavski... (iTelescope observatory, X07 (remotely from Rio Hurtado Valley, Chile))

🌟 30 Years Since the Discovery of Comet Hale-Bopp! ☄️ On July 23, 1995, amateur astronomers Alan Hale and Thomas Bopp independently discovered a comet that would go on to wow the world , Comet Hale-Bopp (C/1995 O1)

Now on the #arXiv: Howell et al. 2025, "The Probable Direct-Imaging Detection of the Stellar Companion to Betelgeuse" - arxiv.org/abs/2507.15749

#bskycometography no. 246 23P/1847 O1 (Brorsen-Metcalf) 1847 Jul 20: Disc by T. Brorsen (Germany) at 9.5 mag. The comet passed perigee on Aug 6 (0.65 au) & perihelion on Sep 10 (0.49 au). It reached ~6-7 mag & was last seen on Sep 13. Period 73.1 yr. Recovery in 1919 by J. Metcalf. ☄️🔭 #CometWatch

FACT THREAD on New Interstellar Object #A11pl3Z This story unfolded pretty fast yesterday for a few reasons. The object was discovered on July 1st UTC by the Asteroid Terrestrial-impact Last Alert System, or ATLAS team. A #NASA funded survey at the University of Hawaii. atlas.fallingstar.com 🔭🧪

I confirmed new interstellar object A11pl3Z remotely using iTelescope.Net T72 (0.51-m f/6.8 reflector + CCD) in Chile. I stacked 5x20 sec. images with Lum filter, measured the magnitude 17.5 G for 2025 07 02.315637 UT. @astrodave.bsky.social @davidbflower.bsky.social #StormHour #PhotoHour #astronomy

Did someone say #NationalCameraDay? 📷 We wanted to celebrate ours by creating a giant 3200-megapixel group photo inspired by our LSST Camera...and here it is, featuring many of YOU! Grab this epic group photo at rubinobservatory.org/gallery 🔭🧪

Did you know YOU will be able to work on NSF–DOE Rubin Observatory data in your free time as a volunteer scientist?🔭🧪 We've partnered with the Zooniverse, a platform where researchers build projects for volunteer scientists. Find out more at rubinobservatory.org/explore/citizen-science 📷: B. Quint

A visual look at two possible orbits for Planet Nine—one based on @plutokiller & @kb4batygin’s model, the other inspired by a recent IRAS/AKARI paper (arXiv:2504.17288) by @takao_nakagawa, @AmosChen, @frosztfang, @NomisOh, and @seongjin_torres.

One of my favorite images from the Cassini era. H/T to John Spencer, Southwest Research Institute, Boulder, CO for reminding me of it. live.staticflickr.com/6193/6209087...

I have a couple of thoughts about the new paper the finds a candidate Planet Nine in some old data. First, it is difficult to tell how seriously to take this because a false alarm probability is never discussed, and second, if it is real, it is not Planet Nine. Read on: 🧵🔭🧪 arxiv.org/abs/2504.17288

Finally! The paper is out! Want to see a naked eye daylight comet? Mark your calendars for 2097! At least if the "ancestry line" given in the paper is correct. Sadly, I won't live to see it. Would I bet my money? I'd say yes. www.sciengine.com/JAHH/doi/10.... ☄️🔭 #CometWatch #histsci #histastro

Planet Nine on NPR! And me! And @vrubinobs.bsky.social. What more could you want? www.npr.org/2025/04/09/n...

Object SWAN25F 2025 Apr. 07.49 UT m1=8.5: Dia.=&3.2' Tail>33' in PA 298 deg... [T26] 0.51-m f/3.0 Cassegrain + CMOS... T. Prystavski... iTelescope observatory, U94 (remotely from Great Basin Desert, Beryl Junction, Utah, USA) [morning twilight: Sun alt. -17 deg.]

Here's an image by Michael Jäger taken this morning. 1.5° ion tail with a knot. Will probably designated C/2025 F2 (SWAN). forum.vdsastro.de/viewtopic.ph... ☄️🔭 #CometWatch

Spent the early morning trying to confirm a possible new SWAN comet with an 50-mm lens and a DSLR. Reached barely 10 mag low above the horizon and found a faint, 10 mag green smudge close to the expected area. Won't report it until better confirmation is available. Now off to work. 🔭☄️ #CometWatch