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Kelly Lepo

@kellylepo.bsky.social
3.5K followers 359 following 1.2K posts

Astronomer | Science communicator | Adult Lisa Simpson Freelance writer and editor. Former Education and Outreach Scientist at the Space Telescope Science Institute (@stsci.edu) supporting JWST. Also on Mastodon: @KellyLepo@scicomm.xyz

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Kelly Lepo @kellylepo.bsky.social · 30/09/2026
Didn't realize that the original image had a transparent background and Bluesky would render that as black, making the axes unreadable. Anyway, here is a diagram showing the opacity of the Earth's atmosphere by wavelength of light.
Plot of atmospheric opacity vs. wavelength. On the y-axis, values range from 0% opacity to 100% opacity. On the x-axis, values range from 0.1 nm to 1 km. Gamma rays, X-rays, and ultraviolet light are blocked by the upper atmosphere (best observed from space). This wavelength range, from about 0.1 nm to 100 nm, is shown at 100% opacity. Visible light is observable from Earth, with some atmospheric distortion. Visible light is represented by a rainbow at around 300 to 700 nm. From about 100 nm to 10 microns, the opacity dips to near zero, with some narrow bands, shown as spikes, which reach near 100% opacity. Most of the infrared spectrum is absorbed by atmospheric gases (best observed from space). From about 10 microns to 1 cm, the atmosphere is mostly at 100% opacity. Radio waves are observable from Earth. From about 1 cm to 10 m, the atmospheric absorption is 0. Long-wavelength radio waves are blocked. From about 10 m to 10 km, the atmospheric opacity is 100%.
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Kelly Lepo @kellylepo.bsky.social · 30/09/2026
Smile's Ultraviolet Imager works at 160–180 nm, observing a band of ultraviolet emission from collisions between molecular nitrogen and energetic electrons from the solar wind that are channeled along the Earth’s magnetic field lines. Credit: ESA
Infographic presenting the different parts of Earth's magnetosphere and its interaction with the solar wind. At the centre of the graphic is Earth, with magnetic field lines emanating from the north/south poles. On the Sun-facing side of Earth, a large shield labelled bow shock seems to protect Earth from the solar wind. On the space-facing side of Earth, the magnetic field lines stretch out into space.
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Kelly Lepo @kellylepo.bsky.social · 30/09/2026
Here is a diagram showing the opacity of the Earth's atmosphere by wavelength of light. There are only a few windows where we can see in or out, where the opacity drops to near 0%. Luckily for our DNA, the Earth's atmosphere blocks most ultraviolet and all X-ray and gamma-ray light. Credit: NASA
Plot of atmospheric opacity vs. wavelength. On the y-axis, values range from 0% opacity to 100% opacity. On the x-axis, values range from 0.1 nm to 1 km. Gamma rays, X-rays, and ultraviolet light are blocked by the upper atmosphere (best observed from space). This wavelength range, from about 0.1 nm to 100 nm, is shown at 100% opacity. Visible light is observable from Earth, with some atmospheric distortion. Visible light is represented by a rainbow at around 300 to 700 nm. From about 100 nm to 10 microns, the opacity dips to near zero, with some narrow bands, shown as spikes, which reach near 100% opacity. Most of the infrared spectrum is absorbed by atmospheric gases (best observed from space). From about 10 microns to 1 cm, the atmosphere is mostly at 100% opacity. Radio waves are observable from Earth. From about 1 cm to 10 m, the atmospheric absorption is 0. Long-wavelength radio waves are blocked. From about 10 m to 10 km, the atmospheric opacity is 100%.
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Kelly Lepo @kellylepo.bsky.social · 28/08/2026
Mooon. #eclipse
In a night scene, a tiny, partially eclipsed moon peeks out between clouds. The bottom half of the moon is red, and the top half is white. The rest of the frame is filled with green trees, partially lit by an unseen light.
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Kelly Lepo @kellylepo.bsky.social · 27/07/2026
Stopped by the Smithonian Air and Space museum this weekend to say hi to the Hubble model. I also got to see the backup mirror (that was not ground to the wrong curvature) and the actual Hubble WFPC2 instrument that astronauts returned from space.
A wide angle video of me standing in front of a full scale model of the Hubble Telescope. Hubble appears as a large (school-bus) sized metal tube. I'm raising my eyebrows, making a face, and pointing like I'm in a YouTube thumbnail.Me standing in front of Hubble's spare mirror. I'm smiling and making the Vulcan salute with my hand. The mirror is a large white disk with a waffle pattern, covered in clear material, with a circular hole in the center. Behind it is the base of the Hubble model.Snapshot of the Hubble WFPC2 instrument behind glass. There is a metal plate on front with small holes drilled in it. Behind it is the instrument, which is roughly wedge shaped and made of black and silver metal.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2026
I mean, maybe my Astro 101 students don't get excited about solar neutrinos, but seriously: en.wikipedia.org/wiki/Sudbury...
A wide-angle view of the SNO detector interior, showing an acrilic sphere filled with water surrounded by a geodesic sphere filled with photomultiplier tubes, which appear as silver circles.
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Kelly Lepo @kellylepo.bsky.social · 07/05/2026
Ugh. This is happening at the worst possible time. I have two days to finish all of my grading and set up three sections of summer class, and Canvas gets hacked 🫠
Still from the Simpsons. A cute puppy holds an electrical plug, appearing to have pulled it from an outlet. Text: Technical difficulties please stand by.
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Kelly Lepo @kellylepo.bsky.social · 18/01/2026
Working in astronomy outreach, you quickly learn that the average person knows way less than you think. It's fine! You can live your whole life without knowing if the Sun is a star. I know because it is my job, most people don't have to. But asking questions is the first step to learning more.
XKCD comic featuring two stick figures. Ponytail and Cueball are talking. Ponytail has her hand raised, palm up, towards Cueball.
Ponytail: Silicate chemistry is second nature to us geochemists, so it's easy to forget that the average person probably only knows the formulas for olivine and one or two feldspars.
Cueball: And quartz, of course.
Ponytail: Of course.
Caption below the panel: Even when they're trying to compensate for it, experts in anything wildly overestimate the average person's familiarity with their field.
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Kelly Lepo @kellylepo.bsky.social · 14/01/2026
xkcd.com/2762/
The comic is a drawing of a star, with the diffraction spikes that usually happen when taking pictures with telescopes. An exoplanet orbits that star, and its trajectory crosses one of the spikes. At the intersection point, the onomatopoeia "SLICE" is written, and the trajectory splits in two. Not far after, two half-planets continue their course.
Caption below panel: Bad news for exoplanets: it turns out those diffraction spikes are real.
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Kelly Lepo @kellylepo.bsky.social · 02/01/2026
🤔 I think the dictionary is telling me I should get back into making sourdough.
Screenshot of a gif, text reads:
Merriam-Webster Your 2026 Word
yeasty
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Kelly Lepo @kellylepo.bsky.social · 19/12/2025
First image: Wavelengths of light emitted by stars. We see millions of stars in the Milky Way, the Large and Small Magallanic Clouds, and some background galaxies. Second image: Wavelengths of light emitted by polycyclic aromatic hydrocarbons (red), a type of cosmic dust, and hydrogen gas (blue).
An all-sky image, projected into an oval shape, centered on our Milky Way galaxy. A bright white band made of tiny white points of light runs horizontally across the image, this is the disk of the Milky Way.  In the center of the image is the bulge of the Milky Way, seen as a fuzzy white sphere that extends slightly above and below the plane of the disk. Dust, seen as an irregular, translucent yellow-orange band, obscures some of the Milky Way's disk. Above and below the plane of the disk, there are numerous white dots, which are stars and background galaxies. To the bottom right, below the disk of the galaxy are the Milky Way's two tiny companion galaxies, the Small Magellanic Cloud and the Large Magellanic Cloud. The Small Magellanic Cloud appears a a fuzzy circular shape. The Large Magellanic Cloudis an oval shape, with a denser bar at its center.An all-sky image, projected into an oval shape, centered on our Milky Way galaxy. A bright white band runs horizontally across the image, this is the disk of the Milky Way. Red dusty gas fills the area above and below the disk, forming loops and patchy areas. Closer to the plane of the disk are blue, circular features, which are hot hydrogen gas. The features are smaller on the left side of the image and larger on the right side of the image. To the bottom right, below the disk of the galaxy, is the Large Magellanic Cloud, a companion galaxy to the Milky Way. It has a patchy oval shape.
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Kelly Lepo @kellylepo.bsky.social · 15/12/2025
I had a blast walking with the @stsci.edu float for the Mayor’s Christmas Parade in Baltimore on Sunday.
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Kelly Lepo @kellylepo.bsky.social · 12/12/2025
One of my favorite recent JWST images, Pismis 24, is now available as a free downloadable poster. Perfect for printing and decorating your walls. It includes the image on the front and a description in both English and Spanish on the back. 🔭🧪 science.nasa.gov/asset/webb/p...
A vertically oriented poster with an image of Pismis 24 against a black background. A dark blue sky filled with white and yellow stars of different sizes covers about two thirds of the image. Across the bottom third of the scene are orange, mountain-like clouds with spire-like peaks that point toward a wispy white cloud which stretches horizontally across the scene. Dense clouds of a similar color are spread about the top right corner of the image. Along the bottom is a series of thin vertical bars ranging from purple at left to blue, green, yellow, orange, and red at right. Bars are separated slightly, with black in between. Bar colors are brightest at the bottom, fading up to black. Brightness varies from bar to bar, giving the array an undulating feel. At upper right is text that reads, “National Aeronautics and Space Administration” and NASA’s blue, white, and red meatball insignia. Title text appears at lower left that says, “James Webb Space Telescope: Pismis 24.”
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Kelly Lepo @kellylepo.bsky.social · 19/11/2025
For about 25 years in their 190-year orbit, a pair of Wolf-Rayet stars in the Apep system get close enough that their winds collide. The colliding winds produce carbon-rich dust that surrounds the stars in a shell. The shells then get blown outward by the winds. 2/
Four translucent dust shells expand away from three central stars that appear as a single pinpoint of light. Bright, arcing ridges partially outline the shells. The innermost shell is smallest, like the size of a thumbprint, and brightest. It is yellow and forms a backward lowercase e. A line at 3 o’clock swoops to the bottom-left in an arc that ends at 8 o’clock. A second line at 9 o’clock dips down to start, but then goes straight up, angling around the top. The second shell, about the size of a fist, is orange and has looser arcs. One appears from 4 to 7 o’clock. A brighter orange triangle appears from 10 to 12 o’clock. Its outer edges overlap, forming a rough circle. The third shell extends almost to the edges and is semi-translucent red, with similar arcs and a darker red line that also forms a faint triangle at top left. The widest shell is faintest and at the edges. A semi-transparent blue appears across the scene. A larger foreground star with spikes is at bottom left, and more distant stars and galaxies are strewn across the black expanse of space.
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Kelly Lepo @kellylepo.bsky.social · 13/11/2025
Not quite as good as last night, but you could see faint aurora tonight from north of Baltimore, MD. 🔭🧪
A night scene showing the sky with faint red aurora. In the bottom quarter of the frame are some trees and a row of houses in the distance. Above is the night sky. Near the horizon is a faint red glow, the aurora, which almost looks like a thin, red cloud. Dotted across the sky are stars, which appear as points of light. A night scene showing the sky with faint red and green aurora. In the bottom quarter of the frame are some trees and a row of houses in the distance. Above is the night sky. Near the horizon is a faint green glow. Above this are two red patches to the left and right of center. They almost look like thin, red clouds. Dotted across the sky are stars, which appear as points of light.
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Kelly Lepo @kellylepo.bsky.social · 12/11/2025
Time-lapse video of tonight's auroras from Maryland, about 4 minutes of real time. I didn't think to bring a tripod, so this was the best I could do, propping my phone up on a stake holding a bush.
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Kelly Lepo @kellylepo.bsky.social · 12/11/2025
Auroras from north of Baltimore, MD. Taken with a long exposure on my phone. They are just barely visible to the naked eye. 🔭🧪
A night scene showing the sky lit up with red and green auroras. The lower half of the frame is filled with silhouetted trees. The upper half shows the night sky. Near the horizon, the sky glows green. Above this is a wide, faint red band with smaller red streaks. A few stars appear as points of white.A night scene showing the sky lit up with red and green auroras. The lower half of the frame is filled with silhouetted trees. Leaves from a tree are out of focus in the foreground near the left edge of the frame. The upper half shows the night sky. Near the horizon, the sky glows green. Above this is a wide, red band with smaller red streaks. Above this are thin, white clouds. A few stars appear as points of white.
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Kelly Lepo @kellylepo.bsky.social · 01/10/2025
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 · 01/10/2025
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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Kelly Lepo @kellylepo.bsky.social · 14/09/2025
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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Kelly Lepo @kellylepo.bsky.social · 12/09/2025
Pre-show organ music and JWST images at the Fox Theater in Visalia.
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Kelly Lepo @kellylepo.bsky.social · 12/09/2025
This week I'm in California for the Sequoia and Kings Canyon Dark Sky Festival. Tonight we kicked off the festivities in Visalia with a screening of Cosmic Dawn followed by a Q&A. I'll be giving a public talk about how JWST finds its way in space and time on Sunday at 7:30 pm at the Wuksachi Lodge
The Fox theater in Visalia, CA at night. Above the theater the name "Fox" and a clock are lit up in neon lights. It is 8:00. The marquee reads "Free Movie Cosmic Dawn, Sponsored by Sequoia Parks Conservatory, 9/11 6pm."
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Kelly Lepo @kellylepo.bsky.social · 31/08/2025
I wish I took more photos when I was there, but this is me at the gift shop of Stark Trek experience when I was at Star Trek: Las Vegas in 2006. I was very committed to having a wedding on the bridge of the Enterprise D, I was sad that it closed before I could.
A 21-year-old Kelly in a blue Star Trek Enterprise jumpsuit looking surprised at a life-sized Borg Queen.A 21-year-old Kelly in a blue Star Trek Enterprise jumpsuit standing next to a life sized Ferengi waiter from Quark's bar. I'm trying to mimic his crossed arm pose. I have red eyes from the camera flash.
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Kelly Lepo @kellylepo.bsky.social · 20/08/2025
Happy #NeutronStarWeek! Want to get a start on your astronomy-themed Halloween programming? Check out the webinar and resources from NASA's Universe of Learning Science Briefing - Cosmic Chills: Vampire Stars, Black Widow Pulsars, and Dark Energy. www.universe-of-learning.org/contents/eve...
An illustration of an ominous, green bat that emerges from the cosmos, pushing objects like galaxies and stars further apart into the void of outer space.
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Kelly Lepo @kellylepo.bsky.social · 20/08/2025
I'm Kelly. I'm an education and outreach scientist based at @stsci.edu in Baltimore. I help make the discoveries of space telescopes like JSWT accessible to everyday people. I also made @arpbot.bsky.social that posts pictures of cool-looking interacting galaxies.
Me recreating a famous image from the movie Contact. I'm standing below one of the radio dishes from the Very Large Array. I'm wearing a straw hat, holding large over-the-ear headphones to my ears, and staring off into the distance, as if I'm thinking about signals from alien civilizations. My long hair is in two braids.Photo of me giving a presentation in front of a huge screen showing a picture of a nebula. The image is scattered with stars that have JWST's characteristic 8-pointed diffraction spikes. The Webb telescope logo is in the corner of the image. I'm wearing a sparkly tiara and several glow necklaces. My long hair is in tight waves.
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Kelly Lepo @kellylepo.bsky.social · 14/08/2025
While the foreground galaxy is warping the light from the background galaxy, they are nowhere near each other, so they are not gravitationally interacting. I'm not sure of the exact separation, since there is nothing published about this pair, but they are probably billions of light years apart.
This ray diagram, which traces the path that light takes, illustrates how light from a distant galaxy or star can be bent by the gravity of an intervening galaxy cluster. 

Light from a galaxy in the top left corner of the diagram is shown moving toward Earth at the bottom right corner. Between the distant galaxy and Earth, in the center of the diagram, is a depiction of a massive galaxy cluster: A series of gold dots representing galaxies of various sizes scattered across the center of the scene. 

Solid white lines that end in arrows show the actual paths of the light from the distant galaxy as it travels to Earth. Dashed white lines with arrows show the paths the light would have taken had it not been bent by the gravity of the intervening cluster. 

The solid white lines start out straight in the beginning, but when they reach the intervening central galaxy cluster, two of the three light paths (the left and right) are bent by the cluster’s gravity and redirected toward Earth. The third solid white line (middle) travels straight from the distant galaxy through the galaxy cluster to Earth. 

The dashed white lines begin at the middle of the cluster, at left and right, and continue on a straight path.
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Kelly Lepo @kellylepo.bsky.social · 08/08/2025
No one quoting that particular "Harvard Astronomer" should be taken seriously.
And I know Loeb can do the work — making “Harvard astronomer” the scientific equivalent of “Florida man” didn’t just happen; it took long-term dedication. I want to believe Loeb and collaborators can delve once more into literature they aren’t familiar with, boldly ignore key papers and misquote others, tear down the barriers between science and sloppy statistics, and once again find bold and inspiring ways for aliens to be hiding under every asteroid, meteor and comet, all in the fashion to which we’ve all grown accustomed.
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Kelly Lepo @kellylepo.bsky.social · 07/08/2025
Congrats on being verified @stsci.edu. You are now in the club with such luminaries as @neorsd.org and @cpsc.gov.
Screenshot of the handle for the Space Telescope Science Institute, @stsci.edu. It has a blue check after it.
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Kelly Lepo @kellylepo.bsky.social · 01/08/2025
The Space Telescope Science Institute's MAST archive contains 300 million astronomical observations from over 23 different missions. Here is an animation showing how the archive has built up over time. Credit: Julie Imig, STScI
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Kelly Lepo @kellylepo.bsky.social · 25/07/2025
Exoplanets Program Guide Includes: • Observe, Think, Wonder or Cosmic Stories warmup • Build a scale model of the TRAPPIST-1 system • Make Your Own Exoplanet Model — Describe an exoplanet and bring it to life through poster artwork or paper-mache. universe-of-learning.org/informal-edu...
Cosmic Canvas: Exoplanets Program Guide
Exploring the Universe through Art and Astronomy
Above: This scientific illustration shows the seven Earth-sized planets of TRAPPIST-1, an exoplanet system about 40 light-years away from Earth, based on data as of February 2018. Credit: NASA/JPL-
Caltech/R. Hurt, T. Pyle (IPAC)
Astronomy and the Arts: How are they connected?
In astronomy, the process of scientific inquiry mirrors the creative journey of artmaking in many ways. Just as artists observe, interpret, and reflect the world through music, painting, sculpture,
and writing, scientists observe the cosmos, interpret data, and create models to understand its many mysteries. Artistic expression, scientific illustration, and modeling play pivotal roles in exploring the universe and conveying ideas, particularly when faced with the unknowns of the vast and challenging-to-observe universe.
In this program guide, participants will practice skills used in both science and artmaking while learning about exoplanets.
NASA's Universe of Learning
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Kelly Lepo @kellylepo.bsky.social · 25/07/2025
Stellar Evolution Program Guide Includes: • Observe, Think, Wonder or Cosmic Stories warmup • Construct a Star Life Cycle Bookmark • Paint a Star-forming Nebula — Use watercolors to depict how stars, dust, and gas interact in star-forming regions. universe-of-learning.org/informal-edu...
Cosmic Canvas: Stellar Evolution
Program Guide
Exploring the Universe through Art and Astronomy
Above: This artist’s concept shows two stars known as HM Sagittae, where a white dwarf star is pulling
material from its red giant star companion. Credit: NASA, ESA, Leah Hustak (STScI)
Astronomy and the Arts: How are they connected?
In astronomy, the process of scientific inquiry mirrors the creative journey of artmaking in many ways. Just as artists observe, interpret, and reflect the world through music, painting, sculpture, and writing, scientists observe the cosmos, interpret data, and create models to
understand its many mysteries. Artistic expression, scientific illustration, and modeling play pivotal roles in exploring the universe and conveying ideas, particularly when faced with the unknowns of the vast and challenging-to-observe universe.
In this program guide, participants will practice skills used in both science and artmaking while learning about the life cycles of stars, known as stellar evolution.
NASA's Universe of Learning.
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Kelly Lepo @kellylepo.bsky.social · 15/07/2025
That one was actually Stephan's Quintet (and also one of JWST's first images). webbtelescope.org/contents/med... Credit: NASA, ESA, CSA, STScI, u/RubixsQube
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Kelly Lepo @kellylepo.bsky.social · 11/07/2025
The Space Telescope Science Institute maintained hubblesite.org, with more than 30 years of Hubble images and news. This included the original 1995 Pillars of Creation image, which owed its popularity to the early internet. Now it just redirects to NASA.
Three dark, finger-like pillars rise from the bottom to the top of the frame, ending in three points. The edges of the pillars are backlit and have streamers of gas, which look like mist rising from the landscape. The background is opaque, set off in shades of green, dotted with a few pink stars. In the upper right corner is a stair-step-shaped black area where there is no data, typical of images produced by Hubble's WFPC2 camera.
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Kelly Lepo @kellylepo.bsky.social · 26/06/2025
Here is one attempting to eat the Pillars of Creation.
A shot of a pumpkin with the iconic Pillars of Creation carved into it. The pumpkin is lit from within, so the pillars are glowing. A leopard slug sits above the top pillar, happily munching away at the carving.
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Kelly Lepo @kellylepo.bsky.social · 17/06/2025
Here you go, from the Rubin town hall at AAS 😉
A projector screen showing slides: We have a working Rubin Observatory system! 
Images are embargoed until First Look press conference in D.C. on June 23rd.
First look images are shown, mostly blocked with a translucent yellow square so you can't see anything.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
And that was it for AAS 246. I'll leave you with the final sunset from my hotel room taken at 11:30pm.
Sunset on a clear day. The city is in shadow in the foreground. In the background is the Cook Inlet and distant mountains.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
And the timeline for 2026 finding decisions. Since the vast majority of astronomy research, education, outreach depend on federal grants, this will be a hugely consequential year for the field.
Timeline for Fiscal Year 2026 funding decisions
June-July: Details of President's Budget Request for FY26 continue to be released
July 7-10: House Energy and Water Appropriations Bill markup
July 14-17: House Commerce, Justice, and Science Appropriations Bill markup
TBD: Senate Appropriations Bill markup
Fall: House and Senate conference to decide final appropriations bill
By October 1: Either appropriations bills are passed, a continuing resolution is adopted, or the government shuts down.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
As a professional society, AAS has been advocating for its members, following their priorities as outlined in their strategic plan. A timeline of the relevant political situation since January and AAS's actions.
Public Policy Timeline
Jan. 20: Inauguration of Trump. Executive Order 14151 Ending Radical And Wasteful Government DEI Programs And Preferencing.
Jan. 27
NSF freezes grant review and payment
Feb. 26: OMB Memo released about agency RIF and reorganization plans.
Jan. 28: AAS releases a "share your story" form.
Feb. 18: NSF lays off 168 employees.
Feb. 20: AAS releases first Action Alert of the year in support of NASA, NSF, and DOE.
Jan - Feb: AAS Policy Team meets with dozens of offices to discuss the impacts on the community.
Feb. 26: OMB Memo released about agency RIF and reorganization plans.
Feb 28: 30% of Office of Space Commerce is laid off. Some employees were re-hired.
Mar. 5: AAS releases Action Alert about submitting constituent request forms over 100 form requests made!
Mar. 7: First reports of deep cuts. to NASA SMD.
Mar. 7: AAS releases statement in support of NASA SMD. DPS committee Hill visits. Stand Up For Science marches around the country.
Public Policy Timeline
Mar 14: Congress passes full-year Continuing Resolution for FY2025. US judges order Administration to reinstate federal workers.
Mar. 19:First AAS policy webinar on how to advocate for astronomy.
April 2: AAS Congressional Visits Day (38 meetings).
Apr. 8: New Action Alert urging House members to sign letter in support of NASA SMD.
Apr. 11: Detailed rumors of NASA cuts reported from OMB passback.
April 21: New Action Alert in support of NSF.
Apr. 23-24: AAS submits comments about NASA reauthorization bill. New Action Alert in support of DOE.
Apr. 24: NSF director, Sethuraman Panchanathan, resigns.
April 28: AAS solicits info about cancelled federal grants from AAS members.
May 2: Release of "skinny" President's Budget Request (PBR) for FY2026.
May 2-7: AAS releases breakdown of skinny PBR, releases Week of Action, and helps with SPD committee visits.
May 8: NSF ordered to abolish 37 science divisions.Public Policy Timeline
May 16: House Deadline to submit "member requests to Commerce, Justice, and Science Appropriations subcommittee (83 signed NASA SMD letter, 132 signed NSF, and 122 signed DOE Office of Science).
May 19: COMPASSE Webinar on Dark and Quiet Skies Policy
May 22: House passes "One Big Beautiful Bill Act" with provision to auction 600 MHz of spectrum.
May 22: Senate Deadline to submit "member requests" to Commerce, Justice, and Science Appropriations subcommittee (15 signed NASA SMD letter, 38 signed NSF, and 31 signed DOE Office of Science).
May 23: AAS submits a comment on Schedule F proposed rulemaking for federal employees.
May 28: AAS sends letter to Congress about importance of preserving protected frequencies for radio astronomy.
May 28: Rubio announces "aggressive" revoking of Visas for Chinese students.
May 30: AAS and 54 other science organizations send letter to Congress about NSF developments.
May 30: Release of NASA and NSF budget requests for FY 2026.
May 31: White House withdraws nomination of Jared Isaacman as NASA Administrator.
June 3-5: AAS staff meet with Congressional offices about NASA and NSF budget requests.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
And we'll wrap up my #AAS246 posts with the only plenary I got to on day 4: Public Policy Plenary: The Current Landscape for Science Policy and How YOU Can Make a Difference. I have to be a little careful here because of my job, but I will recap what I can of what AAS leadership presented.
The Current Landscape for Public Policy and how YOU can make a difference
Dara Norman and the AAS Public Policy Team (Colin Hamill, Roohi Dalal, Joel Parriott)
6/12/2025
American Astronomical SocietyWhat Policy Looks Like at AAS
AAS Mission Statement
The mission of the American Astronomical Society is to enhance and share humanity's scientific understanding of the universe as a diverse and inclusive astronomical community.
https://aas.org/about/governance/society-resolutionsWhat Policy Looks Like at AAS
Strategic Priority 1: Address significant global issues that affect astronomy
• Advocate for implementation of the Decadal Surveys Recommendations.
• Advocate for STEM education, in coordination with Education Committee goals and initiatives.
• Advocate for funding, programs, policies, and regulations that broadly benefit the discipline.
• Establish and advocate policy and position points concerning outdoor ground-based lighting and protection of the full EM spectrum.
• Establish and advocate policy and position points concerning the increasing satellite presence in Earth orbit.
AAS Strategic Plan 2021-2026: https://aas.org/about/strategic-plan
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
Last thing for day 3 of #AAS246: A panel discussion on the legacy of astronomer Vera Rubin, namesake of the soon-to-be-operational Rubin Observatory. And we were some of the first people to get our hands on the new Vera Rubin quarter, courtesy of the US Mint.
Nicole Drakos stands at a podium. Above here is a large screen showing slides: Vera Rubin's rotation curve measurements gave us the first clear evidence that galaxies are embedded in massive, invisible dark matter halos. Image of Vera Rubin. Plot of rotational velocity vs. distance from center for a spiral galaxy.
Kimberly Arcand, Nicole Drakos, Maddie Lucey, and Amruta Jaodand sit on stage.Four women astronomers, Kimberly Arcand, Nicole Drakos, Maddie Lucey, and Amruta Jaodand sit on stage.A cardboard display with a grid for holding the American Women Quarters. They are all empty except for Dr. Vera Rubin.Closeup of the Dr. Vera Rubin quarter. An older Rubin is shown in profile. United States of America Quarter Dollar. Dr. Vera Rubin, Dark Matter.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
And finally, some advice from Ford, inspired by youtu.be/sTJ7AzBIJoI
Advice
Wear sunscreen
Work with kind people; be kind
Control what you can control
Work sustainably
• Do research
• And community building
• Have hobbies
• Have a plan B
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
Ford's created a population synthesis model for stellar-mass black holes in AGN disks using the McFACTS code. They find that several puzzling observations, including the relative spin orientations of black holes in LIGO, can be explained by a chain of merging stellar-mass black holes.
Let's model that!
Monte carlo For AGN Channel Testing & Simulations
Saavik Ford AMNH, BMCC, CCA, CUNY GC
Barry McKenan AMINH, BMCC CCA, CUNY GC
Harrison Cook NMSU
Vera Deltavero NASA Goddard
Emily McPike AMNH, CUNY GC
Kaila Nathaniel RIT
Shawn Ray AMNH, CUNY GC
Richard O'Shaughnessy RIT
Jake Postiglione AMNH, CUNY GCThings flow around.
Flow chart representing the interactions modeled in the code.
The Eccentric BH population interacts with the Inner disk population leading to EMRIs. The Eccentric BH population also interacts with the circularized BH population, leading to the binary BH population, which goes into the Speriod, then captured by the Circularized BH population and feeds the Inner disk population. The binary BH population also leads to soft BBH, Hard BBH, and merged BBH. Soft BBH can Ionize, leading back to the Eccentric BH population.Conclusions
The AGN Channel: logical
Now have pop synth: McFACTS
Many other logical consequences
• TDEs (and EMRIs)
• Changing look AGN
• QPES
Smoking guns: hi spin/asym χ_eff in upper mass gap.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
This may explain the upper end of the mass of merging black holes seen by LIGO, which are hard to make from the collapse of single, massive stars.
Logical consequences
Masses in the Stellar Graveyard
Ligo observed black holes and neutron stars showing their mass before and after a merger. The most massive pre-merger black holes are over 100 solar masses.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
The stellar-mass black holes will tend to merge and interact, mediated by the gas in the disk. This leads to a long series of heretical mergers, since the kicks from mergers are not enough to eject them from the disk. This is not true in star clusters, where mergers tend to eject black holes.
Logical consequences.
A diagram showing black holes in the disk around a supermassive black hole. 
In the center is the SMBH. Processes illustrated include: 
Dynamical binary formation
Gas-capture binary formation
Binary-single interaction
Migration
Disk capture
Binary disruption
Binary-circumbinary disk interaction
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
It turns out that astronomers have been working on a similar problem for decades, planets in protoplanetary disks. The ratios of mass between planet/star/disk and supermassive black hole/stellar mass black hole/disk are similar.
Any other disks like that?
ALMA images of protoplanetary disks, seen as a series of disks with concentric gaps, at various oreintations.Any other disks like that?
A simulation of a planet embedded in a disk, seen face-on. Interactions between the planet and the disk form spiral arms, with leading and trailing arms that wrap around the disk.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
Our Milky Way doesn't have an active black hole, but active galactic nuclei (AGN) in other galaxies are surrounded by a disk of gas. That means there must be "things" (stellar-mass black holes) in the disks of AGN.
Active galactic nucleus.
In a Hubble image, it just looks like a bright point of light.
A model shows a black hole surrounded by an accretion disk, a dusty torus and a broad line region. Above and below the black hole is a synchrotron jet.A screenshot from a simulation of gas around a black hole from Hopkins+ 25. It looks a little like an over-easy egg, with the yoke to one side.Things in AGN disks.
q= m/M_SMBH
q < 10^-4
An illustration shows a supermassive black hole surrounded by a disk. New stellar mass black holes form in the disk. Other black holes orbit through the disk. A pair of black holes are embedded in the disk.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
We observe a swarm of B-type stars around the Milky Way's resident supermassive black hole, Sgr A*. There also must have been O-type stars in the same region that already ran through all of their hydrogen fuel, and are now unseen neutron stars and black holes.
Our nearest galactic nucleus
Visible: Stars
Not visible: dead stars
Image of stars and their orbits in the area immediately around Sgr A*. It looks like a swarm of bees.
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Kelly Lepo @kellylepo.bsky.social · 14/06/2025
And the final plenary lecture of #AAS246 day 3: Things in Disks: Towards a New Understanding of Galactic Nuclei by K.E. Saavik Ford.
Saavik Ford stands on stage behind a podium. Behind her is a giant screen with slides: Things in Disks: Towards a New Understanding of Galactic Nuclei, K.E. Saavik Ford.
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Kelly Lepo @kellylepo.bsky.social · 13/06/2025
The pre-modern world is a time of patience, teamwork, and creativity. There are some dead ends, but if you persist there is something to pass on to future generations.
Thank You.
A medieval map with hand-drawn images of buildings, waterways, and text.
Image of the book cover: The Light Ages, by Seb Falk.
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Kelly Lepo @kellylepo.bsky.social · 13/06/2025
In part, this was because while latitude is fairly easy to measure, longitude is not (and its zero point is arbitrary). However, it begins to show up in later maps.
Gerard Mercator, Nova et aucta orbis terrae descriptio ad usum navigantium emendate accommodata (1569)
"A new and full representation of the terrestrial globe perfectly adapted for use in navigation"
Map of the Earth using the Mercator projection. Europe and Africa are shown in great detail. Asia is also detailed, alhtough it gets less accurate to the North. North and South America are kind of blobby, although the east coast of North America and the caribbean are more detailed and accurate. In the south Antartica is too big. In the North, there is a land mass around the north pole.
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