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Reposted by Kelly Lepo

Arp Bot 🤖 @arpbot.bsky.social · 2d

Also known as Arp 189.

Daniel Pomarède @pomarede.bsky.social · 3d

CFHT Astronomy Image Of The Month

The Umbrella Galaxy (NGC 4651)

Credits: data obtained using the MegaCam camera on the Canada-France-Hawaii Telescope; image by Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum); copyright © 2025 CFHT
www.cfht.hawaii.edu/HawaiianStar... 🧪🔭

A photography of the spiral galaxy NGC 4651. This member of the Virgo Cluster is known as the Umbrella Galaxy due to the umbrella-shaped structure that extends from its disk and that is composed of stellar streams, being the remnants of a much smaller galaxy that has been torn apart by NGC 4651's tidal forces.

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Reposted by Kelly Lepo

Arp Bot 🤖 @arpbot.bsky.social · 7d

Image of Arp 85, also known as the Whirlpool Galaxy or M51, from Halton Arp's Atlas of Peculiar Galaxies (1966).

In the original catalog it was in the category: Spiral galaxies - Large, high surface brightness companions.
Source

A grainy, black and white image of two galaxies. The larger of the two galaxies, a spiral, is on the left side of the image. Two well-defined arms extend to from its center and form loose spirals around the middle. The smaller galaxy on the far-right side is fuzzy sphere. The view of this smaller galaxy is partially obstructed by the tip of one of the arms of the spiral galaxy, which appears to cover the top third of the smaller galaxy. Many white dots, stars, are seen on the black background.

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Kelly Lepo @kellylepo.bsky.social · 7d

And I'm glad we were finally able to get this article published yesterday, before the government shutdown meant that NASA is no longer updating its website.

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Kelly Lepo @kellylepo.bsky.social · 7d

Is there a line that separates exoplanets with and without atmospheres — called the "cosmic shoreline"?

These stars are very active, sending out X-rays and flares, blasting the planets that orbit them. So it's not clear if we can extrapolate from the solar system. The program tests this hypothesis.

Five solar system objects and 9 exoplanets plotted on a graph titled, “Balance Between Starlight and Gravity: Which Rocky Planets Have an Atmosphere?” Vertical axis labeled, “Amount of High-Energy Light that Reaches the Planet,” with “more” at the top and “less” at the bottom. Horizontal axis labeled, “How Hard It Is for Atmosphere to Escape the Planet’s Gravity” with “needs less energy to escape” at left and “needs more energy to escape” at right. Background grades from black at top left to light blue at bottom right. Label pointing toward top left reads, “Atmosphere less likely.” Label pointing toward bottom right corner reads, “Atmosphere more likely." Key above graph shows that objects plotted as solid blue circles (Mars, Venus, Earth) have atmosphere. Solid gray circles (the Moon, Mercury) have no atmosphere. Open white circles (all nine exoplanets) are not yet determined. Solar system planets fall on the bottom left half of the graph. Exoplanets fall in the top right.

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Kelly Lepo @kellylepo.bsky.social · 7d

We have found many rocky planets orbiting cool, red dwarf stars. But do these planets have atmospheres?

The Rocky Worlds Director’s Discretionary Time program has 500 hours of JWST time plus 250 HST orbits to help answer that question. 🔭🧪

science.nasa.gov/mission/webb...

Illustration showing a distant star, with two rocky planets in the foreground. The star is deep orange and appears to be very active, with dark and light spots and large flares. The planets appear to be the same distance from the star. The planet on the left is significantly smaller than the one on the right. Text beside the planet at left reads, “Smaller planet. Weaker gravity. Lower escape velocity. Atmosphere less likely.” Text for the planet at right reads, “Larger planet. Stronger gravity. Higher escape velocity. Atmosphere more likely.” The small planet at left is gray. The right quarter of the hemisphere is lit by the star. The boundary between the lit and dark sides is sharp. The larger planet at right is blueish white with swirling clouds. The left quarter is lit by the star. The boundary between the lit and dark sides is fuzzy.

Illustration showing two star-planet systems, with stars in the background and planets in the foreground. The planets are the same size, but the stars are different colors and distances. The system on the left side of the graphic shows a star that is deep orange and appears to be very active, with dark and light spots and large flares. It appears to be close to the planet. The planet is gray and looks airless. The left quarter of the hemisphere is lit by the star, with a sharp boundary between the lit and dark sides. Text below the planet reads, “More high-energy light from the star. Atmosphere less likely.” The system on the right side of the graphic shows a star that is yellower and appears to be less active and farther away from the planet. The planet is blueish white with swirling clouds. The left quarter is lit by the star. The boundary between the lit and dark sides is fuzzy. Text below the planet reads, “Less high-energy light from the star. Atmosphere more likely.”

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Reposted by Kelly Lepo

ESA Space Science @science.esa.int · 8d

Stars in our galaxy make a stadium wave, Gaia finds 🙌

Our Milky Way galaxy never sits still: it rotates and wobbles 🌀

But #ESAGaia has just revealed that our galaxy also has a giant wave rippling outwards from its centre 👉 www.esa.int/Science_Expl... 🔭 🧪 ☄️

This image consists of two sides. Left side: A top-down view of a spiral galaxy is shown. It has a bright central bulge with several spiral arms radiating outward. Overlaid on the lower part of the galaxy is a data visualisation, with colours ranging from blue to red. A label reading ‘Sun’ marks a specific location within this overlay. Right side: An edge-on view of the same spiral galaxy is presented. It reveals the galaxy's thin disc and central bulge from the side. Coloured points are scattered along the disc, representing the same data as the overlay on the left side.

The image features a dark background with a thin, bright horizontal line running across the centre. This is our galaxy’s disc. Above and below this line, numerous white arrows point upward and downward. These arrows vary in length and are spread evenly along the line. Scattered among the arrows are small red and blue dots. The visual resembles an astronomical data visualisation, illustrating positions and motions of stars in our galaxy.

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Reposted by Kelly Lepo

SPIE @spie.org · 13d

Space images from Hubble, Webb, Rubin, and Chandra don’t show “true” colors; they translate invisible wavelengths into visible ones. Colorization reveals hidden details and helps us understand the universe. 🔭 🛰️

Read more in the Sept/Oct issue of #PhotonicsFocus!

Astro-color alchemists

Astronomers have a method for colorizing grayscale images from various space- and groundbased observatories.

spie.org

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Reposted by Kelly Lepo

Elise Cutts @elisecutts.bsky.social · 15d

Cecilia Payne-Gaposchkin ✨ figured out what stars are made of ✨ when she was just 25. 🔭🧪

Her PhD thesis basically established the Harvard astro department — at a time when Harvard didn't officially allow woman students.

I wrote this little profile to mark the 100th anniversary of her thesis:

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Reposted by Kelly Lepo

janice @janiceleeastro.bsky.social · 14d

One of my faves, among the galaxies that we're studying. Uncommonly beautiful because of its striking "flocculent" spiral morphology. We've learned its star clusters tell a story of gas accreted from a neighbor, rejuvenating the disk🧪🔭
iopscience.iop.org/article/10.3...
#extragalactic #astrosci

ESA Space Science @science.esa.int · 17d

Spiral, elliptical or neither? 🤔

The latest image from the NASA/ESA Hubble Space Telescope features a hard-to-categorise galaxy, NGC 2775. It has features of both elliptical and spiral galaxies – so what type is it?

Read more 👉 esahubble.org/images/potw2... 🔭

A galaxy seen face-on, with a slightly elliptical disc that appears to have a hole in the centre like a doughnut. In the hole, the core is a brightly glowing point that shines light out beyond the edge of the disc. Around the hole is an inner ring of dust, and at the galaxy’s edge is a thicker outer ring of dust, with a swirling web of dust strands in between. Blue stars and red nebulae are visible behind the dust.

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Reposted by Kelly Lepo

National Weather Service @nws.noaa.gov · 16d

The Fall/Autumnal Equinox is TODAY at 2:19 PM EDT. That's the time at which our Sun is directly over the Earth's equator, signaling the start of Northern Hemisphere astronomical fall. The Earth’s northern hemisphere will continue to tilt further from the sun through the Winter Solstice on Dec 21.

Graphic showing Earth during the June solstice and September equinox. At the equinox, sunlight is evenly distributed along the equator. Text notes Fall Equinox 2025 occurs Sept 22 at 2:19 pm EDT.

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Kelly Lepo @kellylepo.bsky.social · 19d

In case you missed it live, the recording of "Alien Skies: Exploring Distant Exoplanet Atmospheres with Webb", my conversation with exoplanet scientist Dr. Néstor Espinoza from the Space Telescope Science Institute is up on YouTube.

Alien Skies: Exploring Distant Exoplanet Atmospheres with Webb

YouTube video by Space Telescope Science Institute

www.youtube.com

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Reposted by Kelly Lepo

LIGO Scientific Collaboration @ligo.org · 19d

Last Sunday was the 10th anniversary of our first #GravitationalWave detection!

Join us for a thread of celebratory cakes enjoyed by members of our collaboration

First, a cake from @ozgrav.bsky.social Looks like plenty to share?

🖼️: J Powell

🧵🎂 #GW10Years

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Reposted by Kelly Lepo

John F Wu @jwuphysics.bsky.social · 19d

Delighted to see that this year's Ig Nobel Physics Prize is about the phase behavior of Cacio e pepe sauce.

Paper: pubs.aip.org/aip/pof/arti...

Pop Sci article: phys.org/news/2025-09...

2025 Ig Physics Nobel Prize goes to perfect pasta sauce

The Ig Nobel Prize honors research that first makes people laugh, then makes them think. Its 35th award ceremony possibly also makes people hungry: ISTA physicist Fabrizio Olmeda and colleagues resear...

phys.org

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Kelly Lepo @kellylepo.bsky.social · 21d

Join us tonight at 7 p.m ET. I'll be chatting with Dr. Néstor Espinoza about how JWST is Exploring Distant Exoplanet Atmospheres.

Space Telescope Science Institute @stsci.edu · 22d

TOMORROW (Sept. 17, 7 p.m. ET): STScI's Dr. Néstor Espinoza will explore some of the most exciting findings #NASAWebb is unveiling about the atmospheres of distant exoplanets. 🔭 🧪
https://youtube.com/live/i466qvWBQ1o?feature=share

Alien Skies: Exploring Distant Exoplanet Atmospheres with Webb

The James Webb Space Telescope (JWST) is humanity's sharpest eye to look at the infrared Universe. From being able to detect the faint glow of the first galaxies to being able to characterize the atmospheres of Earth-sized worlds, the observatory's uniq...

youtube.com

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Kelly Lepo @kellylepo.bsky.social · 21d

🔭🧪

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Reposted by Kelly Lepo

Dr. Jessie Christiansen @aussiastronomer.bsky.social · 21d

Sometimes 2025 just feels like a lot, and you need an excuse to celebrate your fabulous team (and the whole exoplanet community!) reaching a new milestone…

Happy 6,000 Confirmed Exoplanets Day, everybody!!!!

(You may recognize the narrator of the video at the link! 🫣)

www.nasa.gov/universe/exo...

A close-up photo of a box of cupcakes with gold candles spelling out ‘6000’.

A group of smiling people - scientists, engineers, data analysts and writers - standing behind a table of goodies.

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Kelly Lepo @kellylepo.bsky.social · 21d

First data are back from the Rocky Worlds Director’s Discretionary Time program!

They have 500 hours of JWST time plus 250 HST orbits to help answer the question: "Which rocky planets orbiting red dwarf stars maintain their atmospheres?"

Observations began in July 2025 and continue through 2027.

MAST - Mikulski Archive for Space Telescopes @mast-news.bsky.social · 21d

New HLSP: First results from the Rocky Worlds DDT program are now available at MAST! This release includes calibrated light curves, model fits, preliminary eclipse depth estimation, and auxiliary data for GJ 3929 b. archive.stsci.edu/hlsp/rocky-w... #HLSP #RockyWorlds #JWST #HST #Exoplanets #MAST 🔭

An example fit to a JWST/MIRI F1500W eclipse observation of GJ 3929b collected by the Rocky Worlds DDT Program.

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Reposted by Kelly Lepo

Astronomy on Tap Baltimore @aot-baltimore.bsky.social · 23d

WE ARE SO BACK

Astronomy on Tap Baltimore is coming at you on Tuesday, October 28th, with a spooky evening full of SPACE KNOWLEDGE!

Join us at Guilford Hall Brewery for astronomy talks, space trivia, and other treats (no tricks here!).

Costumes not required, but strongly encouraged!

a black cat is standing next to an orange pumpkin

Alt: a black cat is standing next to an orange pumpkin

media.tenor.com

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Reposted by Kelly Lepo

Emily Hunt @emily.space · 29d

What happens when a star cluster disperses? Well, it forms a stream of stars - and those streams are all around us!

In a new paper by Sebastian Ratzenböck at the CfA / @univie.ac.at, we looked into streams near to the Sun, and found that the Milky Way's disk is *full* of streams! 🔭☄️🧪 #galactic

Figure from the paper showing detected streams in the Milky Way in Cartesian coordinates, where streams are shown as highlighted volumes. The Sun is at X=Y=Z 0 pc (the red cross): so these streams are all around us!

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Reposted by Kelly Lepo

NPR @npr.org · 22d

Pythagorean Triple Square Day, as one man affectionately calls 9/16/25, is a day like no other this century.

On 9/16/25, celebrate a date of mathematical beauty

Pythagorean Triple Square Day, as one man affectionately calls 9/16/25, is a day like no other this century.

n.pr

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Reposted by Kelly Lepo

Sera Markoff @profsera.bsky.social · 22d

Check out our new results on the M87* #blackhole w/ @ehtelescope.bsky.social ! We now have 3 frames in a 4yr "movie", including polarisation ⇔ magnetic fields. It's like tracking extreme sunspots just outside a black hole, the brightness and fields flip, yet the shape stays the same bc...gravity!

A tryptich of three images of the M87* black hole, from April in 2017, 2018 and 2021 (we lost 2019-2020 campaigns to technical/pandemic reasons). The fuzzy red donut shape is the same but the bright spot shifts in 2018 and seems to reset in 2021. Streamlines in the image indicate the polarisation vectors, that trace the magnetic field configuration. This too seemed unusual in 2018 and the whole field configuration flipped direction over the 4 year period!

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Kelly Lepo @kellylepo.bsky.social · 25d

The Sequoia trees here are indeed large.

Me standing under a giant Sequoia tree. It almost looks like a normal tree, until you realize that I am tiny in comparison. It's at least twice as wide as I am tall, and you can only see the base of the tree. It continues up out of the frame. The bottom has a large fire scar, where the bark was burned in a previous fire.

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Reposted by Kelly Lepo

Space Telescope Science Institute @stsci.edu · 26d

We’re seeing double: two interacting galaxies imaged by #Hubble and #NASAWebb. Hubble shows obscuring brown dust and blue star-filled regions, while Webb shows glowing cold dust as white material and pink stars still embedded in dust: https://bit.ly/3F72M4a 🔭 🧪

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Kelly Lepo @kellylepo.bsky.social · 27d

Pre-show organ music and JWST images at the Fox Theater in Visalia.

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Kelly Lepo @kellylepo.bsky.social · 27d

If you haven't seen Cosmic Dawn, you should. It gives you a great behind-the-scenes look at the construction of the JWST. It's available for free on NASA's YouTube channel.

Cosmic Dawn (NASA+ Original Documentary)

YouTube video by NASA

youtu.be

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