Kelly Lepo @kellylepo.bsky.social · 30/09/2026Didn'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. 0121
Kelly Lepo @kellylepo.bsky.social · 30/09/2026Smile'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 112
Kelly Lepo @kellylepo.bsky.social · 30/09/2026Here 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 380
Kelly Lepo @kellylepo.bsky.social · 27/07/2026Stopped 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. 2150
Kelly Lepo @kellylepo.bsky.social · 14/06/2026I mean, maybe my Astro 101 students don't get excited about solar neutrinos, but seriously: en.wikipedia.org/wiki/Sudbury... 1110
Kelly Lepo @kellylepo.bsky.social · 07/05/2026Ugh. 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 🫠 091
Kelly Lepo @kellylepo.bsky.social · 18/01/2026Working 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. 68916
Kelly Lepo @kellylepo.bsky.social · 02/01/2026🤔 I think the dictionary is telling me I should get back into making sourdough. 040
Kelly Lepo @kellylepo.bsky.social · 19/12/2025First 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). 1130
Kelly Lepo @kellylepo.bsky.social · 15/12/2025I had a blast walking with the @stsci.edu float for the Mayor’s Christmas Parade in Baltimore on Sunday. 1100
Kelly Lepo @kellylepo.bsky.social · 12/12/2025One 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... 28320
Kelly Lepo @kellylepo.bsky.social · 19/11/2025For 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/ 150
Kelly Lepo @kellylepo.bsky.social · 13/11/2025Not quite as good as last night, but you could see faint aurora tonight from north of Baltimore, MD. 🔭🧪 0160
Kelly Lepo @kellylepo.bsky.social · 12/11/2025Time-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. 1381
Kelly Lepo @kellylepo.bsky.social · 12/11/2025Auroras from north of Baltimore, MD. Taken with a long exposure on my phone. They are just barely visible to the naked eye. 🔭🧪 315618
Kelly Lepo @kellylepo.bsky.social · 01/10/2025Is 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. 190
Kelly Lepo @kellylepo.bsky.social · 01/10/2025We 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... 1262
Kelly Lepo @kellylepo.bsky.social · 12/09/2025Pre-show organ music and JWST images at the Fox Theater in Visalia. 050
Kelly Lepo @kellylepo.bsky.social · 12/09/2025This 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 2190
Kelly Lepo @kellylepo.bsky.social · 31/08/2025I 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. 2170
Kelly Lepo @kellylepo.bsky.social · 20/08/2025Happy #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... 1223
Kelly Lepo @kellylepo.bsky.social · 20/08/2025I'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. 1473
Kelly Lepo @kellylepo.bsky.social · 14/08/2025While 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. 250
Kelly Lepo @kellylepo.bsky.social · 08/08/2025No one quoting that particular "Harvard Astronomer" should be taken seriously. 161
Kelly Lepo @kellylepo.bsky.social · 07/08/2025Congrats on being verified @stsci.edu. You are now in the club with such luminaries as @neorsd.org and @cpsc.gov. 1230
Kelly Lepo @kellylepo.bsky.social · 01/08/2025The 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 26524
Kelly Lepo @kellylepo.bsky.social · 25/07/2025Exoplanets 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... 150
Kelly Lepo @kellylepo.bsky.social · 25/07/2025Stellar 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... 140
Kelly Lepo @kellylepo.bsky.social · 15/07/2025That 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 120
Kelly Lepo @kellylepo.bsky.social · 11/07/2025The 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. 0102
Kelly Lepo @kellylepo.bsky.social · 26/06/2025Here is one attempting to eat the Pillars of Creation. 160
Kelly Lepo @kellylepo.bsky.social · 14/06/2025And that was it for AAS 246. I'll leave you with the final sunset from my hotel room taken at 11:30pm. 090
Kelly Lepo @kellylepo.bsky.social · 14/06/2025And 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. 150
Kelly Lepo @kellylepo.bsky.social · 14/06/2025As 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. 151
Kelly Lepo @kellylepo.bsky.social · 14/06/2025And 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. 170
Kelly Lepo @kellylepo.bsky.social · 14/06/2025Last 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. 030
Kelly Lepo @kellylepo.bsky.social · 14/06/2025And finally, some advice from Ford, inspired by youtu.be/sTJ7AzBIJoI 120
Kelly Lepo @kellylepo.bsky.social · 14/06/2025Ford'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. 110
Kelly Lepo @kellylepo.bsky.social · 14/06/2025This 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. 110
Kelly Lepo @kellylepo.bsky.social · 14/06/2025The 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. 110
Kelly Lepo @kellylepo.bsky.social · 14/06/2025It 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. 110
Kelly Lepo @kellylepo.bsky.social · 14/06/2025Our 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. 110
Kelly Lepo @kellylepo.bsky.social · 14/06/2025We 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. 110
Kelly Lepo @kellylepo.bsky.social · 14/06/2025And the final plenary lecture of #AAS246 day 3: Things in Disks: Towards a New Understanding of Galactic Nuclei by K.E. Saavik Ford. 210
Kelly Lepo @kellylepo.bsky.social · 13/06/2025The 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. 110
Kelly Lepo @kellylepo.bsky.social · 13/06/2025In 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. 110