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Mike Brown

@plutokiller.com
21K followers 156 following 2.5K posts

Astronomer, planet hunter, Pluto killer, bear whisperer, finger-wrapped dad. Dangerous secularist. Foot soldier in the War on Cars. He/him. mikebrown.caltech.edu

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Mike Brown @plutokiller.com · 25/08/2026
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.
The same yard that I always post, sometimes with Patch, sometimes with bobcats, but this time there is a medium sized black bear (who is an adorable brown blond color) with her cub. I wish I knew how to estimate cub ages.
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Mike Brown @plutokiller.com · 24/08/2026
It is fun for my @scientificamerican.bsky.social piece to drop as I was literally hanging out with this guy
A very large silverback mountain gorilla somewhere in the Bwindi Impenetrable Forest of eastern Uganda. The gorilla is glancing up from his main task of the day (and every day): eating many many plants
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Mike Brown @plutokiller.com · 19/08/2026
As a reward here are some absolute queens from the safety of the handover
Two female lions standing at close range in the Savanah. They are both scanning around looking for lunch (we followed them for an hour but sadly never saw them give chase)
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Mike Brown @plutokiller.com · 19/08/2026
They marched in a line down to the pool. Here are my 5 am pix from the lodge porch with a flashlight. There were many many lions, even if all you can see is fuzzy blobs past the pool. It was an interesting night I must say.
A lion illuminated by a flashlight, about 200!yards away past a pool. The other pictures are basically the same thing.
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Mike Brown @plutokiller.com · 18/08/2026
There is not much left of the buffalo
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Mike Brown @plutokiller.com · 18/08/2026
Except if you look in the middle of those two “tents” there is something oddly red
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Mike Brown @plutokiller.com · 18/08/2026
And here was the view this morning. Spectacular, no?
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Mike Brown @plutokiller.com · 18/08/2026
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
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Mike Brown @plutokiller.com · 17/08/2026
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
Two of the absolute cutest murder kittens I have ever seen sleeping under a treeThe full scene of the tree, four kittens, and the mother
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Mike Brown @plutokiller.com · 16/08/2026
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.
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Mike Brown @plutokiller.com · 15/08/2026
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
A small group of lions lazily lying on the ground in the Savanah all but begging to have their bellies rubbed. Luckily I know that belly rubs can be a trap so I will just be scritching ears
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Mike Brown @plutokiller.com · 13/08/2026
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 🐈
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Mike Brown @plutokiller.com · 12/08/2026
Current status
A pair of Kilimanjaro beers sitting on a table while an eclipse happens elsewhere in the world
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Mike Brown @plutokiller.com · 07/08/2026
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.
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Mike Brown @plutokiller.com · 05/08/2026
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.
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Mike Brown @plutokiller.com · 05/08/2026
Some favorite pictures from Harrison Schmitt’s visit today. See alt text for details!
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Mike Brown @plutokiller.com · 29/07/2026
Finally: me! I am proud to have received the Non-detection Lifetime Achievement Award for a sustained and distinguished record of not finding Planet Nine. It is a picture frame with a picture of Planet Nine (it is a picture frame with nothing in it)
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Mike Brown @plutokiller.com · 29/07/2026
Swaroop Chandra received the Golden Lego Reconstruction Award for restoring order from a thermodynamically favored state. It is a pile of golden Lego, natch. Where did I find golden Lego, they asked. Did no one question the gold spray paint in the lab
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Mike Brown @plutokiller.com · 29/07/2026
Matthew Belyakov received the Emergency Interstellar Response Prize for immediately abandoning all previous research save save an ISO from Loebification (ahem). It is an ambulance sporting important bumper stickers
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Mike Brown @plutokiller.com · 29/07/2026
Ashma Pandya received the Chemistry Supremacy Award for believing that all planetary science is chemistry plus bookeeping. It is a perfect facsimile of a commercial box of sodium bicarbonate (actually it’s just a box of baking soda from Target)
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Mike Brown @plutokiller.com · 29/07/2026
Merritt McDowell received the Periodic Table Starter Kit Award. Contents may become scientifically interesting when exposed to sufficient energy. It is a heroically mounted containers of Morton’s salt along with a CO2 canister and a pencil, obviously.
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Mike Brown @plutokiller.com · 29/07/2026
Bella Mueller received the Sack of Troy Prize for once again making the Trojans do all the work. It is a gold horse because I didn’t have any wooden ones.
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Mike Brown @plutokiller.com · 29/07/2026
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)
Six people standing awkwardly after I told them all to cross their armsSame six people, now Charlie’s Angels style
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Mike Brown @plutokiller.com · 25/07/2026
You must bring me… a shrubbery! (With a baby bobcat inside)
A baby bobcat sits watch on top of a potted shrubbery that my wife has left outside all summer in hopes that it will magically plant itself. It has not planted itself, but the bobcat does not mind as it provides a better perch from which to stalk butterflies, which has been his main activity today that I have watched.
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Mike Brown @plutokiller.com · 21/07/2026
Here is a bear to lower my heart rate
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Mike Brown @plutokiller.com · 18/07/2026
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Mike Brown @plutokiller.com · 17/07/2026
Utterly adorable tiny bob cat kittens in our back yard being watched very closely by indoor cats who are Not Pleased By The Visitors
Two tiny bob cats sit on a rock by a bowl looking about as adorable as should be allowedSame bob cats and bowl.
More adorable as one cat steps up on the edge of the bowl to peer inThree house cats staring out the window longingly
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Mike Brown @plutokiller.com · 07/07/2026
That was such and amazing trip to just walk and laugh and be silly together for 2 weeks across the Dolomites. I can't recommend it enough. But it's still no excuse for her to turn 21.
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Mike Brown @plutokiller.com · 07/07/2026
One of my favorite pictures of the two of us (and now lives as my computer background), resting after a long climb in the dolomites before we head on to our rifugio and another week of hiking
two people sitting int the grass staring across at some amazing dolomite peaks.
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Mike Brown @plutokiller.com · 07/07/2026
Happy birthday to this little bunny who is, inexplicably, 21 years old today. It is pretty hard for me to fathom.
A small blond child in a bunny robe.
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Mike Brown @plutokiller.com · 27/06/2026
On a bike ride on a trail above Pasadena. [Bear appears in trail.] Friends: everyone get off your bike and stand behind it and try to look large Me: [rides straight towards bear] Hey buddy, are you new? I don’t think we’ve met before. [bear ambles down the hill and mostly ignores us]
A black bear standing in the middle of a fire road with trees and a mountain in the background
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Mike Brown @plutokiller.com · 24/06/2026
Virga. Rainbow. Waxing moon. Great blue heron. Sunset clouds. A beautiful evening display in Pasadena.
An orange cloud split by a rainbow with a tiny dot of a heron and a distant dot of a moon
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Mike Brown @plutokiller.com · 23/06/2026
I found an old camera SD full of pictures. They were mostly this mom and her cubs hanging out in our back yard. She just wanted a nap. They just wanted to play.
Black bears (who are brown): Mom naps in a green yard while two cubs box over the top of her body.The cubs wrestling, one with very sharp murder claws prominently visible.One cub resting his entire lower body (how does it even fit?) into a large bowl that used to be full of water but is now full of bear.
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Mike Brown @plutokiller.com · 12/06/2026
I don’t buy gas much but next time I have to I am definitely going here
A sign at a Mobil station where all of the gas is apparently free. This, I believe, is below market rate, but I haven’t bought gas this year so I don’t really know for sure. Maybe I am wrong though and this is what Trump meant when he said that gas was cheap. What do I know?
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Mike Brown @plutokiller.com · 24/05/2026
We have lived here 20 years and I don’t ever remember seeing a fox in the backyard. Cute little buggers.
A quick brown fox looking alert in a back yard. Looking for a lazy dog over which to jump, no doubt.Same fox on the prowl.
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Mike Brown @plutokiller.com · 22/05/2026
Nap time
Patch the bear is sprawled out for an evening nap
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Mike Brown @plutokiller.com · 22/05/2026
Paaaaaatch. First good look at him this season and he has got some serious chonk going on
It’s Patch, the black bear who is brown. He is somewhat spherical.
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Mike Brown @plutokiller.com · 16/05/2026
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Mike Brown @plutokiller.com · 15/05/2026
Weird new pool bears. Can’t quite figure these ones out.
A pair of mallards in my pool.
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Mike Brown @plutokiller.com · 12/05/2026
We are talking about dwarf planets in class today so this seemed like the right shirt to wear for the occasion
A dude (me, I am the dude) wearing a t shirt saying “I had a marvelous time ruining everything.” And, well, I did.
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Mike Brown @plutokiller.com · 11/04/2026
Ready for Artemis return! We’re dressing up right? I even have my iron meteorite cuff links!
Me in a tuxIron meteorite slices on my cuff links
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Mike Brown @plutokiller.com · 06/04/2026
I just signed 190 books in 26 minutes, which I think is a new PR
190 books laid out on 3 tables all turned to the same pageA close up of the book “how I killed Pluto and how it had it coming” some now signed
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Mike Brown @plutokiller.com · 03/04/2026
This is from a year or two ago but I just came across it and had to share again. This is Frank, our recently irradiated cat, meeting a few of his neighbors. He remains a good cat. They are all good cats (Frank is doing well!).
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Mike Brown @plutokiller.com · 01/04/2026
I just do love the cameras on the rocket so we can watch as it goes to space
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Mike Brown @plutokiller.com · 01/04/2026
Today’s socks
Socks with the NASA logo and a crew member holding a flag on the moon
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Mike Brown @plutokiller.com · 26/03/2026
Not a planet
Street scene in downtown LA with a Planet Fitness. People seem confused once again about what is and is not a planet so I am providing this public service to try to help people remember.
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Mike Brown @plutokiller.com · 02/03/2026
Frank is a little sleepy post irradiation, but otherwise seems in good kitty spirits.
Frank, looking a little dazed, inside his cat carrier. He gets to go home now!
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Mike Brown @plutokiller.com · 02/03/2026
This is Frank (Franklin C. Roosevelt, where C is for cat [obvs D was for dog]). He’s going on a trip today. He’s about to get radiation therapy for his just-discovered nasal lymphoma. Wish Frank luck and sweet anesthetized dreams. Wish me the ability to keep it together. Frank is a good boy.
Frank, a brown stripy cat approaching chonk size, is exploring the top of his red carrier.Frank is posing on the fireplace mantle that he is strictly forbidden from visiting. He looks elegant next to an orchid and a print of an octopus.Frank trolls for food in the kitchen with the other two cats, Rosie (the riveter) and Hedy (Lamar). Rosie and Hedy are litter mates who look nothing alike (and don’t like each other). Can litter mates have separate fathers? I am guessing yes. Rosie is about to reach down and swat Frank because it is import that everyone remembers that she is in charge.
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Mike Brown @plutokiller.com · 30/01/2026
New paper just out from my soon-to-graduate Ph.D. student Matthew Belyakov. He got JWST to look at 3I/Atlas in the mid-infrared. And there is water! and CO2! and CH4! and Ni! It's just a beautiful spectrum (and I love a beautiful spectrum). arxiv.org/abs/2601.22034 🔭
Three plots, one showing emission lines of water, one of CO2, and one of methane (which also has a single nickel line in there). The models sit on top of the data and, friends, the models are nearly perfect (thanks PSG).
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Mike Brown @plutokiller.com · 25/01/2026
He is just like a big dog
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