My new paper with Nate Kaib explores what triggered the dynamical instability that took place among the giant planets in the young Solar System. We show that the flyby of a low-mass brown dwarf or free-floating planet could have done it (probability ~5%). ui.adsabs.harvard.edu/abs/2025arXi...

Last week, my son Zack shadowed me at my department for a week. I put him to work but I gave him a choice -- and he decided to simulate rings of planets and stars orbiting a black hole. And he wrote a blog post about it for your reading enjoyment (with gif!) planetplanet.net/2025/12/13/b...

About 100 billion humans have walked the Earth. About 100 billion stars roam the Milky Way galaxy. About 10,000 humans have ever been paid to study the stars (if anyone has better data let me know). So, modern astronomers are each lucky to the tune of 1 in 10 million!

If you live in France, a new documentary about 'Oumuamua comes out Thursday evening, starting at 9pm on the France 5. Replays on france.tv after I was scientific advisor (and I show up in several places), which was a great pleasure. www.francetvpro.fr/contenu-de-p...

I just realized that a couple weeks ago was the fifth anniversary of the release of my astronomy poem book: Black Holes, Stars, Earth and Mars. www.amazon.com/dp/B08LFZZWGZ

Here's a new article I wrote for @nautil.us about a new result hinting that variations in the cosmic ray flux hitting the Earth, which itself varies as the Sun oscillates vertically within the Galaxy, have a strong link to the diversity of microplankton. nautil.us/could-the-su...

New animation of the ultimate engineered solar system for a talk I'm giving tomorrow at a sci-fi convention in Lithuania. It has 400 rocky planets in the habitable zone of a single Sun-like star It's perfectly stable (I simulated it out to about a billion years) planetplanet.net/2017/05/03/t...

AAS members are on the Hill today to #SaveNASAScience and advocate for sustained funding for NASA, NSF, and our nation's other science agencies! Help us amplify their voices by calling and writing to your Congressional offices today: aas.org/action-alert...

In my new @nautil.us article, I use a lot of recent research to argue that rocky exoplanets on eccentric orbits are often very good candidates for life. (At least, eccentric/inclined orbits should not be used as a negative for habitability) nautil.us/wild-orbits-...

Here's something new and weird -- eccentric rings of co-orbital planets. They are stable indefinitely, from an orbital point of view. Could they actually form and exist? planetplanet.net/2025/09/02/e...

Flashback to 2012 when I ate the Sun (Photo from the top of Vulcano in Sicily)

Imagine the complicated and precious genius of the girl who made this embroidery sampler in 1811 The Solar System, sampler, unknown maker, 1811, England. Museum no. T.92-1939. Victoria and Albert Museum, London.

Sigh. sites.psu.edu/astrowright/...

Still can't get over @deschscoveries.bsky.social parodying Loeb, and Loeb straight-up playing out the parody a 3 days later. Is Desch a clairvoyant, or did Loeb read this mockery of him and think—hey, that's actually a great idea!—and just plagiarize him?!

My complaints have not yet been resolved. medium.com/@steve.desch...

Loeb’s bad science flies out faster than any one of us should have to deal with it. For a nice explanation of what’s wrong with many of his claims I have not addressed, see @hectorsocas.bsky.social ’s work here: tinieblasyestrellas.blogspot.com/2025/08/3iat...

Today, *every* living prior leader of NASA's science directorate have released a joint letter condemning the proposed cuts to NASA science. These individuals every administration from Reagan to Biden, and all believe these cuts are insanely destructive: www.planetary.org/press-releas...

Folks need to remember that public funding of science drives economic growth and human quality of life decades into the future. This is about more than saving jobs on the line now. It's about your future health, and the future of health and well-being for the next several generations.

The details are not yet finalized, but the budget bill would devastate NASA science and the future of US exploration in space and astronomy. Among many other things. 🔭🧪 www.planetary.org/articles/nas...

Oh hey I didn't know you were here! I wrote about it too. 😄 www.scientificamerican.com/article/coul...

@nytimes.com article about Nate Kaib's and my recent paper on the future stability of the Solar System when passing stars are accounted for. www.nytimes.com/2025/06/28/s...

Like dinosaurs, Saturn and Jupiter roamed They sculpted this system that humans call home The gas giants roared, the system unstable An ice giant planet fell right off the table! A whole ring of comets was launched to the stars The planets — bombarded — still bear the scars.

I was the scientific advisor for the latest video by Balade Mentale about "World-Killer Planets: The Chaotic History of Planetary Systems" (in French) youtu.be/_6J9axX3r08?...

The Lindy Effect and the stability of planetary systems. Here's one way of thinking about why planetary systems go unstable, and when. planetplanet.net/2025/06/11/t...

From @davidkipping.bsky.social www.youtube.com/shorts/L5Ssn...

A quick update about co-orbital rings of planets. This setup -- with 42 planets (each the same mass as Earth) sharing an orbit that is the same average distance as Earth (1 au) but super-eccentric -- is stable for at least 5 million years. (I'm running it out to a billion years to test)

Need a quick book to read in the bath or at the beach? Even better -- a fun book of astronomy poems to read with your kids to get them interested in science and space? I humbly offer up my book, illustrated by my son Owen (back when he was 12). www.amazon.com/dp/B08LFZZWGZ

The NASA planetary science fleet chart if the president’s budget is enacted.

Nice article about our recent paper (with Nate Kaib) on the future of the Solar System under the effect of passing stars. www.sciencenews.org/article/star...

Giant planets on wide, eccentric orbits (like putative Planet 9) may form when stars are embedded in their natal stellar clusters. Sims suggest a 1-5% chance of such planets forming in exoplanetary systems & up to 40% in the Solar System. https://bit.ly/4dD7VOi #AstroSci

"Do you think Planet 9 exists?" The observational evidence is limited by small number statistics. That's often enough for many to conclude, somewhere between unlikely and no. But, I lean further towards more-likely-than-not, and a new paper out today helps explain why I've thought this way. 1/7

New paper (Izidoro et al) We show that planets on very wide orbits -- such as the proposed Planet Nine -- are an inevitable consequence of dynamical instabilities that happen early in planetary systems, still in their (stellar) birth clusters Paper: rdcu.be/enVEi Quick thread 1/

Hello what have we here? I didn't think this would be stable, but it is! (Planets are 1 Earth-mass each)

In my opinion, the Vera Rubin telescope is the most exciting new telescope since Kepler (no offense to JWST;). First light June 23!

Kilauea is spectacular right now, with fountains reaching maximum heights of up to 300 m! www.youtube.com/live/fiyttmA...

I wrote a blog post about Nate Kaib's and my new paper showing that stellar flybys have a stronger-than-expected effect on the future orbital stability of the Solar System. planetplanet.net/2025/05/13/c... Quick thread

Attention US researchers who want to move to France! #cnrs will be opening positions for those who are affected by the Trump chaos, ranging from postdocs to senior positions. More info can be found here: https://carrieres.cnrs.fr/actualites/international-researchers-jointhecnrs/ #planetaryscience

“Why do we even plan on doing great things if, on a whim, we can just decide ‘nah’?” the senior space scientist says. “These things take a generation to build and enable multiple generations of scientists. They should not be blithely thrown away.” www.scientificamerican.com/article/nasa...

Comet C/2024 G3 (ATLAS) spotted in full glory by #SolarOrbiter. The #comet was observed with the SoloHI instrument from the U.S. Naval Research Laboratory. The encounter happened on 14-25 January, while Solar Orbiter was heading toward #Venus and the comet coincidentally swung by the #Sun. 🔭 🧪

Time for the promised thread on ε Eridani b! I should emphasize this manuscript is a submitted draft—comments from the community are very welcome. Bottom line: ε Eri b is likely a 1.0 Jupiter-mass planet, only 3.2pc away, on a 3.55 AU near-circular orbit, ~aligned with its debris disk. 🔭🪐🧪 [1/7]

The barycenter--the balance point between the Sun & the planets--depends on the solar system's configuration. For the past few years, with big planets gathered to one side, we've been fairly far out of balance. Not saying it's a metaphor, just reporting. 🧪🔭 www.skymarvels.com/gallery/Vid%...

My new article for @nautil.us is out! I present the case that life on giant planet moons may be as abundant in the Galaxy as life on rocky planets. Here's hoping this hypothesis is tested in my lifetime! nautil.us/intelligent-...

Asteroid #2024YR4 is looking a lot less worrisome. Improved orbital calculations reduce the estimated odds of impact in 2032 to just 0.27%. 🧪

Mostly preaching to the choir here, but a group of us moderators over on Reddit's AskScience put together kind of an explainer for the implications of some of the attacks on science funding and infrastructure in the US if it's useful for anyone else to share:

The Threat to the Astrophysics Data System Many times on this blog I have mentioned many times is the SAO/NASA Astrophysics Data System which (for the uninitiated) is a Digital Library portal for researchers in astronomy and physics, operated by the Smithsonian Astrophysical Observatory (SAO)…

The chance of asteroid 2024 YR4 hitting out planet in 2032 is now 1.5%, or 1 in 67. The OVERWHELMING likelihood is that the asteroid will miss Earth. But for the first time ever, we might have to seriously consider a deflection mission soon. Let me explain. 🧵 (1/x)

@briancoxtalks.bsky.social talking about the Grand Tack. Pretty cool when a great science communicator talks about your idea (even if it's a little old now...) youtube.com/shorts/Yrhzx...