a ladder floating in the middle of a blueish green sky leading up the a half moon

how have I never seen this Georgia O'Keefe painting called "Ladder to the Moon" 😭

This week in my "Planets in Science Fiction" class, I will be discussing the amazing short story "Nightfall" by Isaac Asimov and its insights into the nature of scientific bias. Also be sure to check out the incredible work of @planetplanet.bsky.social at planetplanet.net.

It's official. I just took over as the new director of the Laboratoire d'Astrophysique de Bordeaux (@labastrobordeaux)!

It's a whole new gig -- wish me luck!

Bummer! Reminds me of the Kepler-186 triple transit of 2014 that we didn't get time to observe

planetplanet.net/2014/06/04/s...

Was the Solar System's dynamical instability triggered by a (sub)stellar flyby? An instability among the giant planets' orbits can match many aspects of the Solar System's current orbital architecture. We explore the possibility that this dynamical instability was triggered by th...

Looks like the link's not working. You can access the paper here: arxiv.org/abs/2512.07979

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!

Here's a teaser: me on the beach showing how a basketball does not match 'Oumuamua's light curve!

My favorite was the "making a comet" demo with dry ice, or maybe going to check out the Vera Rubin telescope in Chile.

France TV - Replay et Direct tv des chaînes France Télévisions (ex Pluzz) Retrouvez toutes les vidéos, articles et podcasts des programmes des chaînes de France Télévisions.

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...

Black Holes, Stars, Earth and Mars: Astronomy poems for all ages Black Holes, Stars, Earth and Mars: Astronomy poems for all ages [Raymond, Sean, Raymond, Owen, Tyson, Neil deGrasse] on Amazon.com. *FREE* shipping on qualifying offers. Black Holes, Stars, Earth and Mars: Astronomy poems for all ages

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 is a link to the original article, by Ozsvart et al: arxiv.org/pdf/2509.04165

Could the Sun’s Orbit Shape Evolution? Could the Sun’s Orbit Shape Evolution? The connection between our massive star and the tiniest microplankton.

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...

The Nautilus Reading List About the Cosmos The Nautilus Reading List About the Cosmos: Our writers have read a universe of books on the cosmos. Here are their favorites.

nautil.us/the-nautilus...

The main challenge is the alternating prograde and retrograde rings of planets.

To build a single ring, I think you's need to pass through a horseshoe constellation phase (see planetplanet.net/2023/04/20/c...) and then damp out the librations. Obviously not feasible for humanity at the moment....

I guess it would be transits, not eclipses, but if the planets had moons they would also be blocking the light from the other planets all the time. A very astronomically-engaging place to be!

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...

See for example this paper : ui.adsabs.harvard.edu/abs/2009ApJ....

Thanks!

If there was a very large amount of internal heat flux from tidal dissipation, it would likely be bad for habitability if the planet is close to the inner edge of the habitable zone, or good if it's beyond (colder).

The planet's orbit would also change (slowly) due to tidal dissipation.

Wild Orbits Prime Planets for Life Looking for habitable worlds? Check the ones with extreme swings.

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-...

It would be interesting to see what the mass ratio threshold is for stability -- does it have to be 1.000000 or could it be 1.01, 1.1, 2., ...?

Ask away. In terms of stability, eccentric rings are clearly stable for billions of years if left undisturbed. I wrote a paper about the dynamical stability of the circular-orbit case when it's perturbed -- it's more robust than you might think.

ui.adsabs.harvard.edu/abs/2023MNRA...

I haven't studied that carefully for eccentric rings. For circular rings of planets, I wrote a paper about it. The punchline is that they're pretty robust. When kicked, these systems often transition to a horseshoe state, unless they're kicked really hard...

ui.adsabs.harvard.edu/abs/2023MNRA...

That's a great idea to check!

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)

a 19th century embroidery sampler showing the solar system, the distance of the planets from the sun, and the length of time it takes each planet to circle the sun

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.

HST Has Conclusively Shown that Avi Loeb is Wrong About 3I/ATLAS The recent JWST observations have firmly shown that 3I/ATLAS is a comet—an interesting and anomalous one in some ways, but definitely not a spacecraft. This has not stopped Avi Loeb from continuing to...

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

Next comes a by-now routine dismissal of astronomical observations, in order to claim 3I/ATLAS’s dusty coma (which does exist: de la Fuente Marcos et al.; Seligman et al.; Bolin et al.) does not exist and is just photographic fuzz. What would be bold and novel would be to lean in to the observations of dust and assert that any spaceship coming in hot from the interstellar medium would be very dirty and in need of a wash.

Impacts by interstellar dust particles and interstellar gas particles can easily create a thin layer of dust on the surface of 3I/ATLAS, with no accompanying ices if 3I/ATLAS is not a comet. The interstellar speed of 3I/ATLAS is ~60 kilometers per second relative to the local interstellar medium. Any impacting matter would deliver ten times more energy per impacting proton than required to break a single chemical bond within the solid surface. The microscopic breakup of the surface to super-micron fragments by interstellar impactors, such as dust, gas and cosmic-ray particles, might have led over billions of years to the formation of large dust particles that are released close to the Sun and account for the glow ahead of 3I/ATLAS in its Hubble image.

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?!