Sierra Grant
@sierragrant.bsky.social
Carnegie Fellow at the Earth and Planets Laboratory. Protoplanetary + circumplanetary disks. Formerly at MPE, BU, and University of Michigan. She/her. #BiInSci 🏳️🌈✨🔭 Opinions are my own.
sierragrant.com
sierragrant.com
Reposted by Sierra Grant
What a year for the James Webb Space Telescope! From identifying frozen water in a young star system to wowing us with great images of the distant universe, Webb has exceeded our expectations in 2025. 🔭
https://youtube.com/shorts/kf-mjdxK6KM
https://youtube.com/shorts/kf-mjdxK6KM
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December 31, 2025 at 5:08 PM
What a year for the James Webb Space Telescope! From identifying frozen water in a young star system to wowing us with great images of the distant universe, Webb has exceeded our expectations in 2025. 🔭
https://youtube.com/shorts/kf-mjdxK6KM
https://youtube.com/shorts/kf-mjdxK6KM
Reposted by Sierra Grant
In a recent SETI Live, @goastromo.bsky.social spoke with @sierragrant.bsky.social and @gcugno.bsky.social about their analysis of CT Cha b – a distant, planetary-mass companion surrounded by a compact moon-forming disk. 🧪 🔭 👩🔬
Learn more: www.seti.org/news/baby-mo...
Learn more: www.seti.org/news/baby-mo...
December 17, 2025 at 8:19 PM
In a recent SETI Live, @goastromo.bsky.social spoke with @sierragrant.bsky.social and @gcugno.bsky.social about their analysis of CT Cha b – a distant, planetary-mass companion surrounded by a compact moon-forming disk. 🧪 🔭 👩🔬
Learn more: www.seti.org/news/baby-mo...
Learn more: www.seti.org/news/baby-mo...
Reposted by Sierra Grant
#ICYMI: During our latest #SETILive, Moiya chatted with Sierra Grant and Gabriele Cugno about the potentially moon-forming disk around exoplanet CT Cha b and its high carbon molecule content. Watch the full episode: youtube.com/live/t1pz56F...
December 6, 2025 at 10:01 PM
#ICYMI: During our latest #SETILive, Moiya chatted with Sierra Grant and Gabriele Cugno about the potentially moon-forming disk around exoplanet CT Cha b and its high carbon molecule content. Watch the full episode: youtube.com/live/t1pz56F...
@gcugno.bsky.social and I had a wonderful discussion with @goastromo.bsky.social for @setiinstitute.bsky.social LIVE about our work on the circumplanetary disk around CT Cha b!
December 4, 2025 at 8:15 PM
@gcugno.bsky.social and I had a wonderful discussion with @goastromo.bsky.social for @setiinstitute.bsky.social LIVE about our work on the circumplanetary disk around CT Cha b!
Reposted by Sierra Grant
Next #SETILive: Baby Moons in the Making?
TODAY, 4 December, 11:00 am PST
@goastromo.bsky.social welcomes two leading researchers—Gabriele Cugno & @sierragrant.bsky.social—to dive into a carbon-rich, moon-forming disk around the distant exoplanetary object CT Cha b, some 625 light-years away. 🧪 🔭 👩🔬
TODAY, 4 December, 11:00 am PST
@goastromo.bsky.social welcomes two leading researchers—Gabriele Cugno & @sierragrant.bsky.social—to dive into a carbon-rich, moon-forming disk around the distant exoplanetary object CT Cha b, some 625 light-years away. 🧪 🔭 👩🔬
December 4, 2025 at 6:00 PM
Next #SETILive: Baby Moons in the Making?
TODAY, 4 December, 11:00 am PST
@goastromo.bsky.social welcomes two leading researchers—Gabriele Cugno & @sierragrant.bsky.social—to dive into a carbon-rich, moon-forming disk around the distant exoplanetary object CT Cha b, some 625 light-years away. 🧪 🔭 👩🔬
TODAY, 4 December, 11:00 am PST
@goastromo.bsky.social welcomes two leading researchers—Gabriele Cugno & @sierragrant.bsky.social—to dive into a carbon-rich, moon-forming disk around the distant exoplanetary object CT Cha b, some 625 light-years away. 🧪 🔭 👩🔬
Reposted by Sierra Grant
Why? NASA is a crown jewel of US science and an international inspiration. Its logo adorns hoodies worn by young and old. The most famous telescopes could not have existed without Goddard and shutting down parts of it, even temporarily, cuts off the life blood for future missions. Why kill NASA?!?
An important new story on the quiet gutting of one of NASA's most important laboratory campuses, during the federal shutdown. Via @ellanilsen.bsky.social & @jackiewattles.bsky.social www.cnn.com/2025/11/04/s...
Workers fear NASA is quietly gutting the iconic home of Hubble and Webb. The agency says it’s strategically closing buildings | CNN
Buildings at Goddard’s Maryland campus are being emptied and padlocked, sources say. NASA leadership has pushed back against the concerns.
www.cnn.com
November 4, 2025 at 9:18 PM
Why? NASA is a crown jewel of US science and an international inspiration. Its logo adorns hoodies worn by young and old. The most famous telescopes could not have existed without Goddard and shutting down parts of it, even temporarily, cuts off the life blood for future missions. Why kill NASA?!?
Reposted by Sierra Grant
AAS Nova turned 10 this year! For our 2,000th post, we’re looking back on the past decade of astronomy research. aasnova.org/2025/10/03/a... @aas.org 🔭🧪
AAS Nova Celebrates 10 Years of Astronomy Research News
AAS Nova turned 10 this year! For our 2,000th post, we're looking back on the past decade of astronomy research.
aasnova.org
October 3, 2025 at 4:11 PM
AAS Nova turned 10 this year! For our 2,000th post, we’re looking back on the past decade of astronomy research. aasnova.org/2025/10/03/a... @aas.org 🔭🧪
Reposted by Sierra Grant
Moon formation drama, a bit more understood 🌚
The NASA/ESA/CSA James Webb Space Telescope has found evidence of a ‘construction yard’ for moons around a large exoplanet, CT Cha b, which lies 625 light-years from Earth.
Read more 👉 www.esa.int/Science_Expl... 🔭 🧪 ☄️
The NASA/ESA/CSA James Webb Space Telescope has found evidence of a ‘construction yard’ for moons around a large exoplanet, CT Cha b, which lies 625 light-years from Earth.
Read more 👉 www.esa.int/Science_Expl... 🔭 🧪 ☄️
September 29, 2025 at 2:11 PM
Moon formation drama, a bit more understood 🌚
The NASA/ESA/CSA James Webb Space Telescope has found evidence of a ‘construction yard’ for moons around a large exoplanet, CT Cha b, which lies 625 light-years from Earth.
Read more 👉 www.esa.int/Science_Expl... 🔭 🧪 ☄️
The NASA/ESA/CSA James Webb Space Telescope has found evidence of a ‘construction yard’ for moons around a large exoplanet, CT Cha b, which lies 625 light-years from Earth.
Read more 👉 www.esa.int/Science_Expl... 🔭 🧪 ☄️
Reposted by Sierra Grant
Cugno and Grant @sierragrant.bsky.social with “A Carbon-rich Disk Surrounding a Planetary-mass Companion” detected using #JWST - an impressive detection of several different carbon molecules that are very promising for #exomoon formation around the directly imaged #exoplanet CT Cha b ☄
September 30, 2025 at 7:34 AM
Cugno and Grant @sierragrant.bsky.social with “A Carbon-rich Disk Surrounding a Planetary-mass Companion” detected using #JWST - an impressive detection of several different carbon molecules that are very promising for #exomoon formation around the directly imaged #exoplanet CT Cha b ☄
Reposted by Sierra Grant
Space Telescope Science Institute: NASA’s JWST Studies Moon-Forming Disk Around Massive Planet science.nasa.gov/science-rese...
NASA’s Webb Telescope Studies Moon-Forming Disk Around Massive Planet - NASA Science
NASA’s James Webb Space Telescope has provided the first direct measurements of the chemical and physical properties of a potential moon-forming disk
science.nasa.gov
September 29, 2025 at 5:04 PM
Space Telescope Science Institute: NASA’s JWST Studies Moon-Forming Disk Around Massive Planet science.nasa.gov/science-rese...
Reposted by Sierra Grant
#NASAWebb has found the first direct evidence of potential moon formation around a giant exoplanet. The discovery is shedding light on how such systems evolve and why moons could be potentially habitable worlds: https://bit.ly/46xGodN 🔭 🧪
September 29, 2025 at 2:10 PM
PRESS RELEASE DAY! Could not be prouder of this result and so happy that it's now out!!! 🤩✨
Thanks to the team at @stsci.edu for the wonderful write-up and image!
Thanks to the team at @stsci.edu for the wonderful write-up and image!
#NASAWebb has found the first direct evidence of potential moon formation around a giant exoplanet. The discovery is shedding light on how such systems evolve and why moons could be potentially habitable worlds: https://bit.ly/46xGodN 🔭 🧪
September 29, 2025 at 4:09 PM
PRESS RELEASE DAY! Could not be prouder of this result and so happy that it's now out!!! 🤩✨
Thanks to the team at @stsci.edu for the wonderful write-up and image!
Thanks to the team at @stsci.edu for the wonderful write-up and image!
Reposted by Sierra Grant
TOMORROW: Two talks, one big night of discovery!
Join Earth & Planets Laboratory postdocs Sierra Grant & Shubham Kanodia as they reveal how planets are born—and the giants that defy the rules. #NeighborhoodLecture
📅 Sept 25 | 6:30 PM ET | DC & Online
🔗 RSVP: carnegiescience.edu/birth-worlds...
Join Earth & Planets Laboratory postdocs Sierra Grant & Shubham Kanodia as they reveal how planets are born—and the giants that defy the rules. #NeighborhoodLecture
📅 Sept 25 | 6:30 PM ET | DC & Online
🔗 RSVP: carnegiescience.edu/birth-worlds...
Birth of Worlds, Rise of Giants
Join Carnegie postdocs Shubham Kanodia and Sierra Grant as they explore the secrets of distant worlds—from the birth of new planets to giant rule-breakers that defy expectations—in a special double…
carnegiescience.edu
September 24, 2025 at 5:37 PM
TOMORROW: Two talks, one big night of discovery!
Join Earth & Planets Laboratory postdocs Sierra Grant & Shubham Kanodia as they reveal how planets are born—and the giants that defy the rules. #NeighborhoodLecture
📅 Sept 25 | 6:30 PM ET | DC & Online
🔗 RSVP: carnegiescience.edu/birth-worlds...
Join Earth & Planets Laboratory postdocs Sierra Grant & Shubham Kanodia as they reveal how planets are born—and the giants that defy the rules. #NeighborhoodLecture
📅 Sept 25 | 6:30 PM ET | DC & Online
🔗 RSVP: carnegiescience.edu/birth-worlds...
Reposted by Sierra Grant
The best part of my job is the people I get to work with 🪐💙
September 21, 2025 at 1:57 AM
The best part of my job is the people I get to work with 🪐💙
Reposted by Sierra Grant
🤯🤯🤯 circumstellar disk chemistry? No, circumPLANETARY disk chemistry!
What an INCREDIBLE result! Check it out below ⬇️🧪🔭🪐
What an INCREDIBLE result! Check it out below ⬇️🧪🔭🪐
Today is a special paper day for me: for the first time we can do chemistry in a circumplanetary disk around a planetary-mass companion! Gabriele Cugno and I used JWST to tease out the signal of CT Cha b, finding a rich carbon chemistry (7 molecules + 1 isotopolog detected)! arxiv.org/abs/2509.15209
September 19, 2025 at 4:13 PM
🤯🤯🤯 circumstellar disk chemistry? No, circumPLANETARY disk chemistry!
What an INCREDIBLE result! Check it out below ⬇️🧪🔭🪐
What an INCREDIBLE result! Check it out below ⬇️🧪🔭🪐
Reposted by Sierra Grant
🪐🔭 JWST is letting us learn about disks around PLANETARY-MASS OBJECTS!!!
Today is a special paper day for me: for the first time we can do chemistry in a circumplanetary disk around a planetary-mass companion! Gabriele Cugno and I used JWST to tease out the signal of CT Cha b, finding a rich carbon chemistry (7 molecules + 1 isotopolog detected)! arxiv.org/abs/2509.15209
September 19, 2025 at 3:57 PM
🪐🔭 JWST is letting us learn about disks around PLANETARY-MASS OBJECTS!!!
Today is a special paper day for me: for the first time we can do chemistry in a circumplanetary disk around a planetary-mass companion! Gabriele Cugno and I used JWST to tease out the signal of CT Cha b, finding a rich carbon chemistry (7 molecules + 1 isotopolog detected)! arxiv.org/abs/2509.15209
September 19, 2025 at 3:22 PM
Today is a special paper day for me: for the first time we can do chemistry in a circumplanetary disk around a planetary-mass companion! Gabriele Cugno and I used JWST to tease out the signal of CT Cha b, finding a rich carbon chemistry (7 molecules + 1 isotopolog detected)! arxiv.org/abs/2509.15209
Feel free to reach out if you have any questions about Carnegie! It's an amazing place to be a postdoc!
The advertisement for Carnegie EPL's 2026 postdoctoral fellowship is out! aas.org/jobregister/... We are also happy to host external fellowships like NHFP, NSF, and 51 Peg b (the latter is due Oct 3rd, one month away!). Please feel free to reach out if you have questions. (1/2)
aas.org
September 4, 2025 at 1:18 AM
Feel free to reach out if you have any questions about Carnegie! It's an amazing place to be a postdoc!
Another MINDS JWST paper! We explore the stark transition from H2O-dominated spectra in Sun-like systems to the carbon-rich chemistry seen for low-mass objects. We don't know exactly what is driving this trend, but we explore the possibilities that may be acting in concert.
arxiv.org/pdf/2508.04692
arxiv.org/pdf/2508.04692
August 7, 2025 at 3:33 PM
Another MINDS JWST paper! We explore the stark transition from H2O-dominated spectra in Sun-like systems to the carbon-rich chemistry seen for low-mass objects. We don't know exactly what is driving this trend, but we explore the possibilities that may be acting in concert.
arxiv.org/pdf/2508.04692
arxiv.org/pdf/2508.04692
New MINDS paper from Nicolas Kurtovic, focused on binary systems. Spectra, extended emission, variability, multi-observatory analysis -- there's something for everyone!
arxiv.org/pdf/2508.02576
arxiv.org/pdf/2508.02576
August 5, 2025 at 6:49 PM
New MINDS paper from Nicolas Kurtovic, focused on binary systems. Spectra, extended emission, variability, multi-observatory analysis -- there's something for everyone!
arxiv.org/pdf/2508.02576
arxiv.org/pdf/2508.02576
Our cat, but now in spherical form 😍
And here's the 40-degree spherical harmonic expansion of my cat 😭😭😭
June 17, 2025 at 6:42 PM
Our cat, but now in spherical form 😍
A spotted star, a (very!) misaligned planet, and awesome gifs, what more could you want?! 🤩
TOI-3884 b is a planet around an M dwarf whose transits show persistent spot crossings. We show that the star's rotational and spot-crossing variations can be modeled with a misaligned planet transiting a large polar spot (confirming last week's results from Mori et al.)
arxiv.org/abs/2506.11998
arxiv.org/abs/2506.11998
June 16, 2025 at 2:40 PM
A spotted star, a (very!) misaligned planet, and awesome gifs, what more could you want?! 🤩
Reposted by Sierra Grant
Now published in AJ! We used Tierras to measure the 23-day rotation period of a K dwarf and found that the orbit of its transiting planet is aligned with the star's spin axis. Stay tuned as we measure true obliquities for a larger sample!
iopscience.iop.org/article/10.3...
iopscience.iop.org/article/10.3...
June 13, 2025 at 5:55 PM
Now published in AJ! We used Tierras to measure the 23-day rotation period of a K dwarf and found that the orbit of its transiting planet is aligned with the star's spin axis. Stay tuned as we measure true obliquities for a larger sample!
iopscience.iop.org/article/10.3...
iopscience.iop.org/article/10.3...
Great work by Kielan Hoch and team on this incredible two-planet system!! We will revisit this target with MIRI-MRS next year to hunt for molecules in the disk around planet b, in a program led by Gabriele Cugno and me, and with Kielan's expertise on the system 🥳🪐
Beautiful new results from my @stsci.edu colleagues Kielan Hoch and collaborators (on here: @mattkenworthy.bsky.social, @offallingstars.bsky.social , @bmacastro.bsky.social , @balmer.bsky.social) with JWST + MIRI www.theguardian.com/science/2025...
Astronomers left puzzled by high-altitude clouds forming on young planet
Experts say thick slabs of cloud in YSES-1 system could consist of mineral dust and iron, which would rain down
www.theguardian.com
June 11, 2025 at 12:10 AM
Great work by Kielan Hoch and team on this incredible two-planet system!! We will revisit this target with MIRI-MRS next year to hunt for molecules in the disk around planet b, in a program led by Gabriele Cugno and me, and with Kielan's expertise on the system 🥳🪐
Reposted by Sierra Grant
Save NASA Science: Please join me in signing this petition from The Planetary Society, urging Congress to reject the deep cuts to science that have been proposed by the administration. www.planetary.org/advocacy-act...
Advocacy Action Center
The Planetary Society is organizing a new space constituency that is educated, empowered, and loud.
www.planetary.org
June 1, 2025 at 9:47 PM
Save NASA Science: Please join me in signing this petition from The Planetary Society, urging Congress to reject the deep cuts to science that have been proposed by the administration. www.planetary.org/advocacy-act...