Mike Brown
@plutokiller.com
Astronomer, planet hunter, Pluto killer, bear whisperer, finger-wrapped dad. Dangerous secularist. Foot soldier in the War on Cars. He/him.
mikebrown.caltech.edu
mikebrown.caltech.edu
Pinned
Mike Brown
@plutokiller.com
· 23d
Mike Brown is very sorry, but Pluto still isn’t a planet
On the 20th anniversary of Pluto’s infamous demotion, Mike “Pluto Killer” Brown explains why any reversal of that decision would be driven more by nostalgia than science
www.scientificamerican.com
My thoughts on the 20th anniversary of the correction of Pluto’s classification (edited by the fabulous @leebillings.bsky.social )
I think they don’t even know that Patch is the Offical Pool Bear of Bluesky
(Also, Patch is awol and plausibly near the end of his expected lifespan and it makes me very very sad)
Bears in Los Angeles Are Getting Their Close-Ups, Ready or Not
(Also, Patch is awol and plausibly near the end of his expected lifespan and it makes me very very sad)
Bears in Los Angeles Are Getting Their Close-Ups, Ready or Not
Bears in Los Angeles Are Getting Their Close-Ups, Ready or Not (Gift Article)
California has 60,000 black bears, and they are venturing far from their usual habitat in search of food and shelter. It’s the humans who have to adapt.
www.nytimes.com
September 8, 2026 at 5:05 AM
I think they don’t even know that Patch is the Offical Pool Bear of Bluesky
(Also, Patch is awol and plausibly near the end of his expected lifespan and it makes me very very sad)
Bears in Los Angeles Are Getting Their Close-Ups, Ready or Not
(Also, Patch is awol and plausibly near the end of his expected lifespan and it makes me very very sad)
Bears in Los Angeles Are Getting Their Close-Ups, Ready or Not
um, no? calling it a planet in 1930 was the actual mistake. but we fixed it and are all good now thanks.
Forbidden planet: was Pluto’s 2006 demotion a big mistake?
Forbidden planet: was Pluto’s 2006 demotion a big mistake?
Since it was stripped of planetary status, Pluto’s defenders have been fighting the decision – and they’re only getting more passionate
www.theguardian.com
August 31, 2026 at 8:25 PM
um, no? calling it a planet in 1930 was the actual mistake. but we fixed it and are all good now thanks.
In Entebbe and headed home from Uganda today and thought I had posted my last wildlife picture, but no. My backyard camera caught a brand new mamma bear and cub. We have definitely not seen them before! I hope they decide they like the neighborhood and consider taking a swim.
August 25, 2026 at 2:29 PM
In Entebbe and headed home from Uganda today and thought I had posted my last wildlife picture, but no. My backyard camera caught a brand new mamma bear and cub. We have definitely not seen them before! I hope they decide they like the neighborhood and consider taking a swim.
It is fun for my @scientificamerican.bsky.social piece to drop as I was literally hanging out with this guy
August 24, 2026 at 1:23 PM
It is fun for my @scientificamerican.bsky.social piece to drop as I was literally hanging out with this guy
My thoughts on the 20th anniversary of the correction of Pluto’s classification (edited by the fabulous @leebillings.bsky.social )
Mike Brown is very sorry, but Pluto still isn’t a planet
On the 20th anniversary of Pluto’s infamous demotion, Mike “Pluto Killer” Brown explains why any reversal of that decision would be driven more by nostalgia than science
www.scientificamerican.com
August 24, 2026 at 12:37 PM
My thoughts on the 20th anniversary of the correction of Pluto’s classification (edited by the fabulous @leebillings.bsky.social )
The lions-don’t-sleep-tonight update. After hearing lions all night long we had to leave at 5am. I sat on the porch for 15 minutes before and heard nothing. When our escort arrived I told him I thought the lions had left. Oh no they are right there, pointing his flashlight 200 yards away to 8 lions.
August 19, 2026 at 3:36 PM
The lions-don’t-sleep-tonight update. After hearing lions all night long we had to leave at 5am. I sat on the porch for 15 minutes before and heard nothing. When our escort arrived I told him I thought the lions had left. Oh no they are right there, pointing his flashlight 200 yards away to 8 lions.
Drama in camp tonight. We are in a “tent” camp (aka cabins with canvas walls) and are not allowed to go from the main dining tent to our tent without a (spear) armed escort. Which seems a little over kill, right? Here is a “tent” with our daughter on the patio
August 18, 2026 at 4:05 PM
Drama in camp tonight. We are in a “tent” camp (aka cabins with canvas walls) and are not allowed to go from the main dining tent to our tent without a (spear) armed escort. Which seems a little over kill, right? Here is a “tent” with our daughter on the patio
I have no pithy comments today except that I just saw baby cheetas sleeping with their mother in the shade of a tree in the Serengeti and now I might be ok for a long time
August 17, 2026 at 3:55 PM
I have no pithy comments today except that I just saw baby cheetas sleeping with their mother in the shade of a tree in the Serengeti and now I might be ok for a long time
I don’t remember the movies well but somehow this makes me think of some scene from Planet of the Apes and I fear it will not end well for us humans. Also this was the largest baboon troop I’ve ever seen. Slightly intimidating.
August 16, 2026 at 2:58 AM
I don’t remember the movies well but somehow this makes me think of some scene from Planet of the Apes and I fear it will not end well for us humans. Also this was the largest baboon troop I’ve ever seen. Slightly intimidating.
I have not yet been eaten by the leopard who hangs around our camp at night but I might end up getting eaten by lions because I really think they need belly rubs
August 15, 2026 at 3:46 AM
I have not yet been eaten by the leopard who hangs around our camp at night but I might end up getting eaten by lions because I really think they need belly rubs
The sun is setting and I am in one of the darkest spots on earth and I am not allowed to go outside at night because apparently there are leopards hanging around 🐈
August 13, 2026 at 4:17 PM
The sun is setting and I am in one of the darkest spots on earth and I am not allowed to go outside at night because apparently there are leopards hanging around 🐈
Look. I’m headed to the tropics tomorrow. And the fact the I am drinking a gin and tonic is only for its antmalarial properties, ok?
August 10, 2026 at 3:27 AM
Look. I’m headed to the tropics tomorrow. And the fact the I am drinking a gin and tonic is only for its antmalarial properties, ok?
My updated class THE SCIENCE OF THE SOLAR SYSTEM is now LIVE and COMPLETELY FREE at www.coursera.com/learn/solar-system
27 hours of lectures, full quizzes, full exam. And free. You can’t even pay if you want to. Or you can just find the lectures on YouTube any time.
27 hours of lectures, full quizzes, full exam. And free. You can’t even pay if you want to. Or you can just find the lectures on YouTube any time.
August 6, 2026 at 11:19 PM
My updated class THE SCIENCE OF THE SOLAR SYSTEM is now LIVE and COMPLETELY FREE at www.coursera.com/learn/solar-system
27 hours of lectures, full quizzes, full exam. And free. You can’t even pay if you want to. Or you can just find the lectures on YouTube any time.
27 hours of lectures, full quizzes, full exam. And free. You can’t even pay if you want to. Or you can just find the lectures on YouTube any time.
I already posted this yesterday but it is an extraordinary picture that I need to reshare. Tony Yap, a Caltech grad student, is showing Harrison Schmitt, Apollo 16 astronaut, a sample that he (Tony) is currently measuring zinc isotopes on. The sample was collected by Harrison Schmitt. From the moon.
August 5, 2026 at 7:58 PM
I already posted this yesterday but it is an extraordinary picture that I need to reshare. Tony Yap, a Caltech grad student, is showing Harrison Schmitt, Apollo 16 astronaut, a sample that he (Tony) is currently measuring zinc isotopes on. The sample was collected by Harrison Schmitt. From the moon.
Some favorite pictures from Harrison Schmitt’s visit today. See alt text for details!
August 5, 2026 at 12:15 AM
Some favorite pictures from Harrison Schmitt’s visit today. See alt text for details!
Wanna hear a talk by Apollo 17 astronaut Harrison Schmitt? It's being lived-streamed here at 2pm PDT. Wanna see ME do the intro and talk a (very) little bit about geology on the moon?Same place. Wanna NOT see me do the intro? Start at about 2:05pm
Also viewable after the livestream. I think.
Also viewable after the livestream. I think.
An Afternoon with Harrison Schmitt
YouTube video by Caltech Astro
www.youtube.com
August 4, 2026 at 7:53 PM
Wanna hear a talk by Apollo 17 astronaut Harrison Schmitt? It's being lived-streamed here at 2pm PDT. Wanna see ME do the intro and talk a (very) little bit about geology on the moon?Same place. Wanna NOT see me do the intro? Start at about 2:05pm
Also viewable after the livestream. I think.
Also viewable after the livestream. I think.
Reposted by Mike Brown
My new paper is out in Science Advances! Neptune's inner moons preserve clay minerals from the deep interiors of ancient icy worlds, exposed by Triton's catastrophic arrival. Here's the story and what it tells us about the violent history of the Neptunian system. 🧵
www.science.org/doi/10.1126/...
www.science.org/doi/10.1126/...
Neptune’s inner moons and rings are exposed icy body interiors
Triton’s destructive wake exposed clay-like minerals from within ancient icy worlds, now reaccreted as Neptune’s inner moons.
www.science.org
July 29, 2026 at 6:36 PM
My new paper is out in Science Advances! Neptune's inner moons preserve clay minerals from the deep interiors of ancient icy worlds, exposed by Triton's catastrophic arrival. Here's the story and what it tells us about the violent history of the Neptunian system. 🧵
www.science.org/doi/10.1126/...
www.science.org/doi/10.1126/...
This is a super cool paper (and last chapter of her PhD thesis) from my now-graduated student @import-astrory.bsky.social
I would explain more but, really, the headline kind of does the job.
I would explain more but, really, the headline kind of does the job.
Neptune's Inner Moons May Be Shattered Remains of Ancient Icy Worlds
New findings from Caltech researchers suggest Neptune's smallest satellites formed from the shattered remains of an original moon system that was destroyed when Triton was captured by Neptune's gravit...
www.caltech.edu
July 29, 2026 at 6:41 PM
This is a super cool paper (and last chapter of her PhD thesis) from my now-graduated student @import-astrory.bsky.social
I would explain more but, really, the headline kind of does the job.
I would explain more but, really, the headline kind of does the job.
Last night was the annual summer dinner and awards presentation for my research group. It was a nice dinner outside on the lawn, but the awards, of course, are the highlights. Follow along (I think the last one is the best though I am perhaps biased)
July 29, 2026 at 5:15 PM
Last night was the annual summer dinner and awards presentation for my research group. It was a nice dinner outside on the lawn, but the awards, of course, are the highlights. Follow along (I think the last one is the best though I am perhaps biased)
You must bring me… a shrubbery! (With a baby bobcat inside)
July 25, 2026 at 12:31 AM
You must bring me… a shrubbery! (With a baby bobcat inside)
I was excited a couple of weeks ago to announce that my my very free revamped Science of the Solar System online class was soon to be up and running on Coursera only to realize today that they no longer all very free classes but will instead charge you $49 for the privilege.
July 23, 2026 at 9:45 PM
I was excited a couple of weeks ago to announce that my my very free revamped Science of the Solar System online class was soon to be up and running on Coursera only to realize today that they no longer all very free classes but will instead charge you $49 for the privilege.
It’s Monday and all accounts are locked down and the scam/theft appears broken up. This morning the MIL mentioned an account she had neglected to tell us about and, yup, they had tried to break in but the bank appears to have shut it down. Seriously. Talk to the people in your life about this stuff.
Fun Saturday night trying to clean up a computer takeover/banking scam my 82-year old mother in law fell for. If you have no yet had the talk with older people in your life please do. She fell for the classic "your computer is compromised call this number" trap. The steps were comically standard:
July 20, 2026 at 9:10 PM
It’s Monday and all accounts are locked down and the scam/theft appears broken up. This morning the MIL mentioned an account she had neglected to tell us about and, yup, they had tried to break in but the bank appears to have shut it down. Seriously. Talk to the people in your life about this stuff.
Fun Saturday night trying to clean up a computer takeover/banking scam my 82-year old mother in law fell for. If you have no yet had the talk with older people in your life please do. She fell for the classic "your computer is compromised call this number" trap. The steps were comically standard:
July 19, 2026 at 2:51 PM
Fun Saturday night trying to clean up a computer takeover/banking scam my 82-year old mother in law fell for. If you have no yet had the talk with older people in your life please do. She fell for the classic "your computer is compromised call this number" trap. The steps were comically standard:
Utterly adorable tiny bob cat kittens in our back yard being watched very closely by indoor cats who are Not Pleased By The Visitors
July 17, 2026 at 2:16 PM
Utterly adorable tiny bob cat kittens in our back yard being watched very closely by indoor cats who are Not Pleased By The Visitors