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Linn Boldt-Christmas

@nplinnspace.bsky.social
3.9K followers 433 following 342 posts

🇸🇪🚀🇪🇺 Astrophysicist in exoplanet science & space policy research 🪐🔭 Also: astrobiology, telescopes, climate, equality/EDI, and scicomm ✨ (she/her) – linnboldtchristmas.wordpress.com

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Reposted by Linn Boldt-Christmas
Paul Byrne @theplanetaryguy.com · 1h
Oh my. The aurora borealis, seen in ultraviolet light from space. Our planet, putting on a show ✨
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Andrew Parsonson @andrewparsonson.bsky.social · 29/09/2026
My latest for SpaceNews: ESA has announced that OHB and Airbus Defence and Space will lead parallel studies for a future European-led space station in low Earth orbit. spacenews.com/esa-announce...
spacenews.com
ESA announces leaders for studies on crewed European space stations
ESA announces leaders for studies on crewed European space stations
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Seven Machina Rasmussen @toomanyspectra.bsky.social · 29/09/2026
HELLO WORLD 🌎🌍🌏 STARSHIPS IS NOW OUT ON 12.5% OF SOLAR SYSTEM PLANETS
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Linn Boldt-Christmas @nplinnspace.bsky.social · 29/09/2026
I somehow missed my own news item, but a little piece about this very fun (sarcasm) work on my love-hate-favourite-enemy #exoplanet WASP-107 b was published by Uppsala University last week! And why do I feel so strongly about an innocent puffy little popcorn? 🫠 Read on! www.uu.se/en/departmen... 🔭🪐
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Clouds Affect Exoplanet Observations More Than Expected – Department of Physics and Astronomy – Uppsala University
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Gene J. Mikulka @genejm1017.bsky.social · 29/09/2026
Just a reminder...
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Linn Boldt-Christmas @nplinnspace.bsky.social · 25/09/2026
I always HATED exams because I was really bad at them. In my physics undergrad, I jokingly wished exams had a Q saying ”whatever topic you studied really well but didn’t come up, write what you know here for extra points”. Now that I’m on the other side (teaching at uni), I kind of still think it 🙃
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SETI Institute @setiinstitute.bsky.social · 24/09/2026
#PPOD: Roman has opened its eyes! These fuzzy rings are the first photons of starlight captured by the Nancy Grace Roman Space Telescope’s 300-megapixel Wide Field Instrument. And yes, they’re supposed to look like that—for now. 🧪 🔭
This test image captures the very first photons of starlight to reach the Wide Field Instrument on NASA’s Nancy Grace Roman Space Telescope. Roman’s primary science instrument has opened its eyes to the universe for the first time, revealing a sea of out-of-focus stars, each spread out over many thousands of pixels. The image, which zooms into one detector and zooms again to a single star in the insets, offers a baseline the Roman team will work from to align the telescope’s optics and tune the focus.
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Linn Boldt-Christmas @nplinnspace.bsky.social · 24/09/2026
🔭
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Jonathan O'Callaghan @astrojonny.bsky.social · 24/09/2026
Updated satellite statistics per planet4589.org/space/stats/... Satellites orbiting Earth: 16,810 Starlink satellites: 11,114 Dead satellites: 3,087 Empty rockets: 2,065
Graph of active satellites orbiting Earth
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CosmicRami 🏳️‍🌈🏳️‍⚧️ @rami.spaceaustralia.com · 24/09/2026
HEO have a fresh new pic of the Chinese Space Station (TIANHE-1) captured from above! This resolution here is 12cm / pixel 🤯🤯🤯
Satellite image of a space station taken from above showing solar panels and modules of station
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Pride in STEM @prideinstem.bsky.social · 23/09/2026
Happy #BiVisibilityDay!
static.klipy.com
Bisexual Pride Heart Animation
Alt: Bisexual Pride Heart Animation
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Dr. Jey McCreight 🏳️‍⚧️🧬 @jeymccreight.bsky.social · 09/09/2026
Reposting because all of my jobs have always come from someone in my network referring me or knowing someone who needs a science communicator 🤞
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Jason Wright @astrowright.bsky.social · 22/09/2026
Back in 2024 I was invited to give a talk at Space Climate 9 in Nagoya, Japan on work by Anna Baum and others at Penn State on Maunder Minimum stars. This is an extension of my thesis work, where I tried to establish whether any other stars were in a state analagous to the Solar Maunder Minimum.🔭🧪
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Das Baskill @drdasb.bsky.social · 21/09/2026
It's that time of the year again! Happy Equinox everyone for Tuesday night / Wednesday morning! The September Equinox occurs this year just after midnight at 00:06UT (01:06BST) on the 23rd September 2026. [1/2]
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Emily Lakdawalla 🏳️‍⚧️ Uranus Expert @elakdawalla.bsky.social · 22/09/2026
This is super cool! And apparently it goes back at least 600 million years
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Michael Busch @michael-w-busch.bsky.social · 21/09/2026
Cool science. Not aliens.
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Guardian US @us.theguardian.com · 21/09/2026
The “jaw-dropping” El Niño currently heating up the planet has burst through the highest temperature ever recorded for the phenomenon, several months before its expected peak.
A line chart showing temperature anomalies in the Niño 3.4 region of the Pacific Ocean, compared to a 30-year rolling base period since 1982.

A gold line shows temperatures in 1997, a teal line in 2025, and a red line in 2026. The red line surpasses all others reaching 3.07ºC, and at an earlier point (September) than the previous El Niño that reached a comparable range in November 2015.
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Michele Bannister @astrokiwi.bsky.social · 21/09/2026
Interested by ISOs like 3I/ATLAS? PhD opportunity in interstellar object observations, here in New Zealand. Join our Ōtautahi-Oxford group & the NZ Gravity collaboration. Start by March 1. ☄️🔭
gravity.ac.nz
PhD Scholarships – Statistics, Astrophysics, Cosmology and Gravitational Wave Astronomy | New Zealand Gravity
About us The NZ Astrostatistics and General Relativity Group (NZ Gravity) is a cross-institutional research team spanning astrophysics, cosmology, ma...
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Melina Thévenot🏳️‍⚧️ @melina-iras07572.bsky.social · 17/09/2026
Proper Motion of stars in the galactic center with #JWST NIRCam F182M. programs: 1306, 4515 www.stsci.edu/jwst-program...
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Katie Mack @astrokatie.com · 20/09/2026
Fully electric aviation has some major challenges (mostly: batteries are heavy and don't get lighter as they get used up) but I love the idea of decreasing aircraft emissions through a hybrid approach, perhaps as a step toward new, clever solutions for fully electric air transport in the future.
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Kerstin Neuhaus @microtopico.bsky.social · 20/09/2026
#Quartz deserves the win. It's the reason that started #MinCup.
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Linn Boldt-Christmas @nplinnspace.bsky.social · 19/09/2026
The battle of common sense vs AI summaries appears to rage on… a relative of mine sent me this screenshot after they tried to find a TV segment I did (SVT = Swedish TV channel). Maybe an exoplanet holiday special could be a thing?! Ho-Ho-HD 209458 b? Chestnuts roasting on an open lava world? 🎅🏻🪐🎄🔥🔭
An AI summary in response to Google search term ”linn boldt christmas svt”. It summarises her work as an astrophysicist but includes the text: ”her connection to SVT (Sveriges Television) is rooted in her work as a scientific expert and communicator rather than a holiday special”
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Kevin Hardegree-Ullman @kevinkhu.bsky.social · 18/09/2026
This is an ultra cool result from @bemiles.bsky.social and team! The brown dwarf community has wanted to get time-series spectra since Spitzer data revealed near ubiquitous broadband variability. TACs take notice, we should study the weather on more brown dwarfs! 🔭
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Sarah E Moran @offallingstars.bsky.social · 18/09/2026
I'm so excited about every single one of these projects-- when you apply to one, note you'll get enthusiastic support from us all across the collaboration ☁️🪐☁️
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Planetary Crater Consortium @planetarycraters.bsky.social · 19/09/2026
Crater Fact Friday ☄️ DID YOU KNOW ☄️ that the Moon has a new crater? Named after lunar scientist Tom McGetchin, this 222-m-diameter crater formed sometimes between April 11 and May 22, 2024, and is an incredibly informative tool to understand the local and regional lunar geologic history.
Figure 1 from the Science paper. The ew impact site, before and after.
(A) NAC image acquired before the impact event, showing undisturbed lunar surface. (B) NAC image acquired after the impact, showing a crater with a bright ejecta blanket.
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Linn Boldt-Christmas @nplinnspace.bsky.social · 18/09/2026
🔭 Really enjoyed stumbling over this paper, and in particular the sass of its title: Saturns Are Not Large Neptunes! Not every day we get a new flavour of #exoplanets — will definitely be using ”Saturnian” from now on 😊 cool work by @niamhk12.bsky.social and others! ✨🪐 arxiv.org/abs/2609.170...
Screenshot of the paper in the link of this post. The section that has been screenshotted is the first part of Section 5 - Conclusions. It reads as follows: 

5 CONCLUSIONS
In this paper we have presented an empirical mass-radius relation
fitted to a sub-sample of the PlanetS catalogue, where inflated giant
planetshave been excluded. Our main results are as follows:
•Weupdatethewell-knownirradiationthresholdforgiantplanet
inflation presented in Demory & Seager (2011), defining 𝑆thr =
99 S⊕, the irradiation below which 90% of giant planets have a
radius excess Δlog 𝑅 < 2𝜎.
•We fitted our mass-radius relation to nine versions of the
inflation-cleaned sample and find that in all cases, a breakpoint was
placedbetweenNeptuneandSaturn,whileineightoutofninethere
wasalsoabreakpoint betweenSaturn and Jupiter.
•Ourbest-fitmass-radiusrelationhasthreebreakpointsandfour
distinctsegments,oneofwhichcorrespondstoaregimeofSaturnian
planets. This newly defined regime is between 54.3 ±2.7 M⊕ <
𝑀 < 257.8 ±10.8 M⊕ and has a slope of 0.270 ±0.007, with a
corresponding radiusrange of 8.0 ±0.5 R⊕< 𝑅 < 12.2 ±0.5 R⊕.
•The lower slope of the Saturnian regime compared to the Nep-
tunian regime (0.668 ±0.007) is consistent with the increased im-
portance of electron degeneracy in hydrogen-rich interiors, and the
corresponding onsetof gravitationalself-compression.
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Chris Lintott @chrislintott.bsky.social · 16/09/2026
Ah, I’ve been waiting for this…
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Caltech IPAC @caltechipac.bsky.social · 15/09/2026
Huge congratulations to the NExScI team on launching AstroFetch! This new tool makes it easier than ever to query #exoplanet science data. 🔭 Give it a spin at exoplanetarchive.ipac.caltech.edu!
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Josh Peek @jegpeek.bsky.social · 16/09/2026
My god… it’s full of point spread functions…
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Bibiana Prinoth @handle.invalid · 15/09/2026
In case you have missed it, we are hosting a super cool workshop on #exoplanets studies in Garching, Vitacura and Nice (YES, 3 places at the same time!!!) in November. Bridging Horizons: Harnessing ESO's current facilities for the dawn of exoplanet population studies Dates: **2-6 November 2026**
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Paul Byrne @theplanetaryguy.com · 12/09/2026
I have a new paper out! Over the weekend I'll do a thread on what the Solar System can tell us about rocky exoplanets— but for now, enjoy this to-scale set of cross sections I made of the rocky worlds in *this* system! (They're all different, but still all variations on a theme...)
Interior structure models of Earth, Venus, Mercury, Mars, the Moon, and Io, all shown to scale and key elements labelled.
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Chris Lintott @chrislintott.bsky.social · 10/09/2026
This is quietly big news for @esa. General chat around #EPSC2026 is a strong desire to reduce dependence on perfidious NASA, driving Europe to new capabilities and partners (see expanding partnership with JAXA for BepiColombo and beyond)
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Markus Pössel @mpoessel.de · 10/09/2026
When we do outreach or education, astronomers frequently claim that public and student interest in astronomy is greater than in other sciences, making it an ideal entry way for science. My article analyzing Wikipedia page views which (somewhat) supports this claim is out in the CAP Journal. 🔭⚛️🧪🎢
capjournal.org
English-speaking Wikipedia users’ interest in astronomy
Wikipedia users’ interest in astronomy is examined using data available for pageviews over the period 2016–2025. Interest, as measured by the level of engagement, is gauged by examining the top 30 ast...
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Laura Kreidberg @lkreidberg.bsky.social · 09/09/2026
Applications are open for Max Planck Research Groups - these are a great gig: six years of funding with support for the group leader + students and postdocs (up to 2.9 MEuro). Contact me if you have any questions about applying for one hosted at MPIA!
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Rikard Enberg @rikardenberg.bsky.social · 09/09/2026
Jag skrev en artikel i Populär Astronomi om gravitationsvågor och det tidiga universum. www.popularastronomi.se/nummer-3-sep...
popularastronomi.se
Nummer 3, september 2026 - Populär Astronomi
I höstens nummer står forskningen vid extremer i fokus. Läs om hyperstjärnorna som rusar igenom galaxen i 1000 meter per sekund och hur fusionskraftverk kan öppna upp den mörka materian. Gästskribente...
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Linn Boldt-Christmas @nplinnspace.bsky.social · 09/09/2026
BepiColombo is so special to me — it was one of the first launches I worked on back in 2018 as a bright-eyed YGT at @esa.int in Paris, and learning about mysterious Mercury made me fall deeper in love with the planetary science that I later did my PhD in. I still have my mug, wrong dates and all! 🥹🔭
An ESA mug with a list of dates for different events of the BepiColombo mission. Several of them are wrong, including the arrival date being listed as 5 December 2025.
Another angle, showing less of the text and instead the mission patch artwork. Is that the mission patch? Or just like a… symbol? Idk it’s been so long that I don’t remember sorry lol
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Dan Turner @ddt.bsky.social · 06/09/2026
The context is "why don't you use AI" and I support this answer. In my field, working through the decisions and the why underpinning decisions is the work and the training and the value you can bring. Offloading this to AI will hamstring you.
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Tod Lauer @todlauer.bsky.social · 05/09/2026
An Earth-mass BH has the size of this black marble. You couldn't get much closer than 100km without being ripped apart by tidal forces. It swallows a Rose Bowl of water in 1s to generate 0.1 solar luminosity (Eddington).
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Laura Kreidberg @lkreidberg.bsky.social · 04/09/2026
Happy to share two postdoc ads for positions in the APEx department at MPIA - please spread the word! - direct imaging and spectroscopy of wide-separation planets with Wolfgang Brandner aas.org/jobregister/... - forward modeling of exoplanet atmospheres with Elsie Lee aas.org/jobregister/...
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Mika McKinnon @mikamckinnon.bsky.social · 04/09/2026
#Bournonite has 4 elements. Some lovely rare metals in the mix, and it can solid-solution on over to incorporate a 5th, but it’d very well-defined. Meanwhile, I straight-up gave up listing all the possible elements in #Vesuvianite because it was too freaking long. The rest. It has all the rest.
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Dr. Jillian Scudder @jillianscudder.com · 02/09/2026
Saturn’s haunted by geometry, apparently
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CosmicRami 🏳️‍🌈🏳️‍⚧️ @rami.spaceaustralia.com · 01/09/2026
This is such a great piece of work. Widely regarded as the first science fiction film. Check out the astronomer outfits! When this film was made, we still didn't know about the Universe expanding, about other galaxies, about the composiition of stars, and Pluto hadn't been discovered!
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Jonathan O'Callaghan @astrojonny.bsky.social · 01/09/2026
whoa
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Linn Boldt-Christmas @nplinnspace.bsky.social · 01/09/2026
Today is Day 1 of my all-time favourite sports tournament: the Mineral Cup #MinCup26 💎🪨 and my annual excuse to talk about pretty crystals for a whole MONTH I’ve been a fan since 2018 (!) and it may even have nudged me into planetary science 🙈 If you’re not familiar, now’s the time to check it out!
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Rocky Worlds Meetings @rockyworlds.bsky.social · 31/08/2026
The goal for the next generation of space missions is biosignature detection on rocky planets. 👽🌱🌍🌌 At the next #RockyWorldsDiscussion on Thu 3 Sep @ 13:00 UTC, Sarah Rugheimer will tell us about one important catch: the planets' UV environments. ☀️🧴 More: www.rockyworlds.org/event-detail... 🧪🔭
An image of the speaker, Sarah Rugheimer. She is smiling and looking into the camera. She has blonde hair and is wearing a green sleeveless outfit with a small gold necklace, black glasses, and a black wristwatch. She stands leaning against a column of beige stone with an open doorway visible behind her.Artist's conception of the Habitable Worlds Observatory, a space telescope, gathering data from a distant star. Image credit: Walt Feimer, NASA Scientific Visualization Studio
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Jeremy Bailin @astrobailin.bsky.social · 30/08/2026
Roman launch transits the sun. From NASASpaceflight feed.
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Saavik ‘Careful of the Ankle’ Ford @saavikford.bsky.social · 30/08/2026
Warning: it’s about to be September and I’m about to be obnoxious for #Calcite (again). This year we WIN THE CUP!!!
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Space Telescope Science Institute @stsci.edu · 30/08/2026
This morning's launch of the Nancy Grace Roman Space Telescope from the Kennedy Space Center was amazing! Roman is now on a million-mile journey to Lagrange point 2, where it will soon reveal the universe’s darkest secrets: go.nasa.gov/4qIa69I #NASARoman 🔭 Credit: J. Barrientes/STScI.
A rocket is launching into the sky from a launch pad, emitting bright flames and smoke. Trees are visible in the foreground.Crowd capturing a SpaceX rocket launch with smartphones, against a sunrise sky.A rocket launches into a cloudy sky, emitting a bright trail of light and smoke.A rocket with a fiery trail ascending into a clear blue sky, leaving a thick plume of white smoke underneath.
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Scott Kardel aka Palomar Skies @palomarskies.bsky.social · 28/08/2026
Two different exposures of tonight's lunar eclipse taken through cirrus clouds near maximum eclipse. 🔭 #eclipse
A 0.3 second exposure of the partially eclipsed Moon. An over exposed area is visible top left. The rest of the Moon is fairly dark with a hint of orange color and dark maria visible.A 1 second exposure of the partially eclipsed Moon. A bright, very over exposed region is visible top left. The rest of the Moon looks orange in color. The dark lunar maria visible.
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Forming Worlds Lab @formingworlds.space · 28/08/2026
The JWST campaign on TOI-561 b, led by @johannateske.bsky.social, continues to deliver surprises! Samuel Boucher (supervised by @astrolisadang.bsky.social) just posted a new phase curve study on this lava world.
JWST phase curve from the general circulation model that best matches TOI-561 b
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