Nostr notes by Prof. Sam Lawler

So the #FediverseChickCountdown was really a bust, only 7 chicks ...

2026-07-13T04:39:38+02:00

So the #FediverseChickCountdown was really a bust, only 7 chicks hatched (and I didn't post much because of fucking Reflect Orbital)

But those 7 chicks are SO CUTE. I reloaded the incubator, turned the temperature down slightly, didn't keep eggs for quite as long, and we'll try this experiment again. Tune in in 3 weeks to find out if I picked the right variables to mess with

(Farming is HARD. Biology is HARD. Orbital dynamics is so easy compared to this!)

GREAT guess I'm not going to sleep tonight either. Maybe ...

2026-07-10T05:46:13+02:00

In reply to nevent1q…wzqc
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GREAT guess I'm not going to sleep tonight either. Maybe there will be auroras. I need to enjoy the night sky as much as I can now, I guess.

Fuck you, FCC, for approving this. Fuck Reflect Orbital and all the copycats it's going to spawn. Fuck techbros everywhere. Fuck venture capitalists for funding this destructive, useless bullshit.

Want some reminders of how fucking terrible this idea is? ...

2026-07-10T05:36:03+02:00

In reply to nevent1q…le7a
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Want some reminders of how fucking terrible this idea is?

https://bigthink.com/starts-with-a-bang/true-cost-solar-power-night-reflect-orbital/

https://theconversation.com/a-us-startup-plans-to-deliver-sunlight-on-demand-after-dark-can-it-work-and-would-we-want-it-to-264323

https://darksky.org/news/organizational-statement-reflect-orbital/

Journalists: please write about how dangerous this is.

Lawyers (especially if you're based in the US): please help fight this, it will take legal action now

FUCK FUCK FUCK FUCK NOOOOO ...

2026-07-10T05:24:55+02:00

FUCK FUCK FUCK FUCK NOOOOO

https://ca.pcmag.com/news/16760/fcc-approves-reflect-orbitals-giant-mirror-satellite-that-astronomers-hate

HAHAHA FUCK SpaceX just launched a nuclear powered satellite. ...

2026-07-08T05:14:07+02:00

HAHAHA FUCK SpaceX just launched a nuclear powered satellite.

https://www.space.com/space-exploration/launches-spacecraft/spacex-just-launched-the-1st-ever-nuclear-powered-commercial-satellite

Sounds like this particular satellite is tiny and doesn't have a lot of tritium on board but HOLY SHIT this is a bad precedent.

Daniel Scheeres (CU Boulder) Binary small bodies are important ...

2026-06-26T16:28:45+02:00

In reply to nevent1q…kjxp
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Daniel Scheeres (CU Boulder) Binary small bodies are important and frequent. How do they form? Even more fun, how do you make 3 component systems (like asteroid Dinkinesh https://en.wikipedia.org/wiki/152830_Dinkinesh)

Lots of simulations! Found an area of energy/angular momentum space that makes triples very easily. Finds lots of contact binaries.

#DDA2026

Ruth Murray-Clay (UC Santa Cruz) "eyehole libration" in ...

2026-06-25T21:17:35+02:00

In reply to nevent1q…t0y0
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Ruth Murray-Clay (UC Santa Cruz) "eyehole libration" in exterior p:1 resonances. We (LiDO) found a 10:1 resonator! I wrote about it for a general audience on page 31 of this pdf: https://www.rasc.ca/sites/default/files/publications/JRASC-2025-10-lr.pdf

In high inclination orbits, p:1 resonances can librate around 180 *or* 0, and switch between these states. Eyehole libration happens when close approach to Neptune isn't at TNO perihelion

I LOVE these beautiful surface-of-section plots Kat Volk makes

#DDA2026

Rosemary Pike (Harvard MPC) my friend and collaborator: results ...

2026-06-25T20:52:55+02:00

In reply to nevent1q…20f4
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Rosemary Pike (Harvard MPC) my friend and collaborator: results from a survey I'm co-PI of, the LiDO survey, 140 new TNOs at 14 degrees or higher inclination.

Hot classical TNO distribution (funny story, this was the most "boring" science case we could think of, but we needed something quick for the survey paper-other for fun science gets its own papers)

We (well, mostly Kat Volk) built a dynamical stability model by mostly filling the hot classical region and eroding (yay REBOUND)

#DDA2026

Time for the outer Solar System! The best dynamics! Nate Kaib ...

2026-06-25T20:43:20+02:00

In reply to nevent1q…halw
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Time for the outer Solar System! The best dynamics!

Nate Kaib (PSI) talking about dynamically new comets (a>10,000AU), talking about pericenter position relative to node, hard to match sims to observations.

There was a star, HD 7977, that passed within 4000-24,000AU from the sun 2.5 million years ago. This would have perturbed lots of comet orbits, simulations with star passes at 6000-10,000AU match current observations much better. We are still living through a comet shower! Cool!

#DDA2026

Sarah Millholland (MIT) Prize lecture, which I missed the first ...

2026-06-24T21:00:17+02:00

In reply to nevent1q…wj6l
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Sarah Millholland (MIT) Prize lecture, which I missed the first few minutes of. Tides are important to explain exoplanets we see.

Super puffs! Some exoplanets are less dense than styrofoam! One possible explanation is tidal heating. Planets misaligned with their stars' spin axis are puffier. Weird.

Realistic exoplanet tides now included in a Reboundx package.

Obliquities also important for tidal migration. Cassini states invoked!

#DDA2026

Seth Jacobson (Michigan State U.) hierarchical triple ...

2026-06-24T19:13:22+02:00

In reply to nevent1q…rkqu
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Seth Jacobson (Michigan State U.) hierarchical triple planetesimal systems should be made during streaming instability for planet formation. Kuiper Belt binaries match predictions from streaming instability well, and there is 1 known hierarchical triples and 2 more candidates.

pkdgrav package good for simulating this, making predictions about what systems we should find in Kuiper Belt at higher resolution: 5% of simulated systems are triples.

#DDA2026

Ygal Klein (Princeton) looking at extreme cases of triple ...

2026-06-24T19:00:10+02:00

In reply to nevent1q…g3yk
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Ygal Klein (Princeton) looking at extreme cases of triple systems. Wacky orbits happen! One problem is that as e->1 (super eccentric) precession starts to do weird things and doesn't necessarily match analytics.

#DDA2026

Mark Dodici (U. of Toronto): looking at eclipsing compact triple ...

2026-06-24T18:41:37+02:00

In reply to nevent1q…eez9
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Mark Dodici (U. of Toronto): looking at eclipsing compact triple star systems (two stars orbiting each other, with a third orbiting the inner two). Outer orbits are very circular in observed systems, must be circularized by tides, will shrink inner orbit. Uses Reboundx to simulate this, helps to hone in on tidal Q parameter. So far, not getting useful results, all outside observations. Still working on it, need better tidal model.

#DDA2026

Great way to end the session with a shout-out to Brian May, who ...

2026-06-24T18:02:05+02:00

In reply to nevent1q…648q
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026

Ashley Espy Kehoe (Embry-Riddle Aeronautical University) ...

2026-06-24T17:59:41+02:00

In reply to nevent1q…65fd
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Ashley Espy Kehoe (Embry-Riddle Aeronautical University)

Recurring theme for Stan Dermott memorial talks: plots are IMPORTANT! (totally agree) So here's a beautiful plot she showed from 1986, that shows how dust bands are created in Solar System (orbital caustics!)

Dust bands tell us about asteroid collisional families. Takes millions of years for full band to form, partial bands give timescales since major collisions, COOL. Dust band structure was confirmed by WISE data.

#DDA2026

J.-C. Liou (NASA Chief Scientist for Orbital Debris!!) Overview ...

2026-06-24T17:44:55+02:00

In reply to nevent1q…3x6c
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J.-C. Liou (NASA Chief Scientist for Orbital Debris!!) Overview of his career work: started with work on zodiacal dust dynamics, with PR drag and resonances. Showed how outer asteroid belt is depleted by Jupiter MMR sweeping. Then dynamics of cometary dust collected from high altitude aircraft, and Kuiper Belt dust structures.

Now works on distribution of human-made debris pieces in orbit. Now at point where collisions dominate debris creation. Active removal required for long-term.

#DDA2026

Mark Wyatt (U. of Cambridge) talking about dynamical effects of ...

2026-06-24T17:25:24+02:00

In reply to nevent1q…k5ru
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Mark Wyatt (U. of Cambridge) talking about dynamical effects of planets on debris disks (I LOVE this stuff). This is true in our own solar system, zodiacal dust is affected by our planets' orbits.

Ooo Fomalhaut, my favourite disk system! The brightness variations in the disk place constraints on the forced eccentricities resulting from unseen planets in the system.

Fom b is a dust cloud, not a planet, which I am incredibly proud I wrote about years ago! Now proven from JWST images!

#DDA2026

I should note that this session (and a at least one other) at ...

2026-06-24T17:14:36+02:00

In reply to nevent1q…sndg
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I should note that this session (and a at least one other) at #DDA2026 are tributes to Stan Dermott, who wrote the Solar System Dynamics bible, and taught a LOT of students.

I guess I have a 1-degree-removed connection here? The postdoc I first worked with, Beth Holmes, who taught me a lot, when I was a baby undergrad, had just finished her PhD with him. (She died from a heart condition while I was still an undergrad)

Apostolos Christou (Armaugh Obs.) this talk title is hilarious ...

2026-06-24T16:58:14+02:00

In reply to nevent1q…sr84
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Apostolos Christou (Armaugh Obs.) this talk title is hilarious "Larger asteroids stay sober, smaller asteroids get drunk"

Wow what a cartoon!

Small asteroids end up with gaussian distributions around the family centre.

#DDA2026

Ben Cassese (MPC): here comes the flood of Solar System small ...

2026-06-23T22:59:30+02:00

In reply to nevent1q…fpan
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Ben Cassese (MPC): here comes the flood of Solar System small body data! Expect 200 million observations per year from Rubin, + 200 million from NEO Surveyor. MPC has to quickly link previous observations into new orbits, this is hard. Will need machine learning to process everything.

#DDA2026

Most super earth systems are not resonant (they don't sound ...

2026-06-23T21:26:45+02:00

In reply to nevent1q…dhnw
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Most super earth systems are not resonant (they don't sound so nice), and lots are near-resonant and sound a little out of tune (some sound quite ominous!)

If you throw a few Plutos in to the system, scattering will disrupt the chain that formed, sometimes leaves them near but not quite in the resonance.

Ends with a note to Kepler (the astronomer) who thought the planets should be in perfect resonance, if not now, maybe when formed. Cool!

#DDA2026

Oooo he's got a bunch of orbital sonification on his website! ...

2026-06-23T21:09:14+02:00

In reply to nevent1q…qn3w
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Oooo he's got a bunch of orbital sonification on his website! https://shadden.github.io/sonification/

Oooo really neat to hear a chord change during an N-body simulation when stability is lost and a planet swaps to a different resonance.

Resonant chain migration behaves like masses on springs, says it's like vibrato! Cool.

"So that's a lot of fun, but so what?" Unstable modes grow or decay depending on how eccentricities are damped.

#DDA2026

Now it's a prize talk by Sam Hadden (CITA) about resonant ...

2026-06-23T20:50:44+02:00

In reply to nevent1q…sldk
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Now it's a prize talk by Sam Hadden (CITA) about resonant planetary systems, and he's PLAYING MUSIC to demonstrate orbits I love this so much (although I have to say it's not working super great over Zoom, sounds drown out the speaker, oh well). Mean-motion resonances function very much like chords! (This is very well explained in this fantastic website, read it all and enjoy: https://www.system-sounds.com/about/)

#DDA2026

Helena Buschermohle (Instituto Nacional de Pesquisas Espacias) ...

2026-06-23T18:58:13+02:00

In reply to nevent1q…96hd
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Helena Buschermohle (Instituto Nacional de Pesquisas Espacias) what happens to moons around circumbinary planets? As planets migrate inwards, Hill sphere gets smaller and moons would become unbound. HAHA she calls stable moons "smoons" and a moon that becomes a planet a "ploonet"

All circumbinary exoplanets discovered so far are gas giants, but maybe moons could be habitable, now that we know some moons survive migration.

#DDA2026

Raluca Rufu (SWRI) high angular momentum impact could well-mix ...

2026-06-23T18:43:25+02:00

In reply to nevent1q…avg0
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Raluca Rufu (SWRI) high angular momentum impact could well-mix Earth's mantle and the moon precursor, but then you have to get rid of excess angular momentum. Dumping that depends on internal thermal evolution of Earth, and its spin. Moon's outward migration speeds up after Earth cools enough to re-solidify, how long solidification takes depends on Earth's atmosphere post-collision.

Evection resonance doesn't seem to remove enough angular momentum.

#DDA2026

Thea Faridani (U. of Rochester) What if we had another Moon ...

2026-06-23T18:27:46+02:00

In reply to nevent1q…u8hu
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Thea Faridani (U. of Rochester) What if we had another Moon closer-in shortly after Moon formation? Impact-migrate-moonlet-merge. Back to REBOUND again! Early results: mutual inclinations and obliquities are really important for keeping moonlets around.

#DDA2026

Between my normal meetings and writing, I'm watching a few ...

2026-06-22T18:13:30+02:00

Between my normal meetings and writing, I'm watching a few talks at the American Astronomical Society's (AAS) Division for Dynamical Astronomy (DDA) annual meeting this week. They have this fantastic option where you pay US$10 and you can watch all the talks at the meeting. I'll try to share summaries of a few highlights using #DDA2026

I cannot believe that in the year 2026, here I am making a ...

2026-06-16T21:09:58+02:00

In reply to nevent1q…93k3
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I cannot believe that in the year 2026, here I am making a pamphlet to help Saskatchewan farm kids identify space junk and get in touch with me.

This is so ridiculous, because:
1. Even though I have seen space junk in Sask with my own eyes, it's still hard to believe that billionaires are dropping it on us frequently enough that this is a thing I need to do.
2. This absolutely should not be my problem. But nobody in the Canadian gov't is willing to accept space junk reports. So here we are!

Yeah. For so many reasons.

2026-06-05T20:26:37+02:00

In reply to nevent1q…x2sj
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Yeah. For so many reasons.

Yeah! 2 SpaceX spacecraft hitting the ground in 2024 in ...

2026-06-05T20:21:58+02:00

In reply to nevent1q…x4vt
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Yeah! 2 SpaceX spacecraft hitting the ground in 2024 in Saskatchewan certainly doesn't give me confidence in that claim, as they make their satellites bigger and bigger... Also if you take their 0.0001 casualty risk at face value, that's still 100 casualties with 1 million sats!!!

I think just laying out the bazillion ways that this is a ...

2026-06-05T18:10:41+02:00

In reply to nevent1q…0n09
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I think just laying out the bazillion ways that this is a completely unworkable, dangerous, polluting idea, with technology that doesn't exist and may be physically impossible. That doesn't hurt at all. I'd say go for it.

Your table is ready, friends. (If you like to eat grass and ...

2026-05-31T19:45:01+02:00

In reply to nevent1q…sfx7
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Your table is ready, friends. (If you like to eat grass and dandelions, that is.)

Happy dandelion day to all who celebrate (mostly ruminants) ...

2026-05-31T19:40:11+02:00

Happy dandelion day to all who celebrate (mostly ruminants)

HAHAHAHA NOOOOOO ...

2026-05-16T15:35:38+02:00

HAHAHAHA NOOOOOO

Today I had coffee with an aerospace engineering postdoc who ...

2026-05-15T22:21:46+02:00

Today I had coffee with an aerospace engineering postdoc who happened to be in Regina briefly. He works on technology for refueling and fixing satellites in orbit, which is EXACTLY the kind of engineering we need! Don't chuck that 3 or 5 year old satellite into the atmosphere, FIX it and make it keep working longer!

Really delightful chat, and the best part is this connection actually happened because of the cow-culation April Fool's day paper I helped write: https://arxiv.org/pdf/2603.29324

I'm sorry that's what you are forced to depend on. Enjoy ...

2026-05-11T18:18:30+02:00

In reply to nevent1q…4dw7
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I'm sorry that's what you are forced to depend on. Enjoy it before SpaceX starts Kessler Syndrome, I guess?

A scary quick calculation: there are 10,375 Starlink satellites ...

2026-05-11T16:35:53+02:00

In reply to nevent1q…3qj7
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A scary quick calculation: there are 10,375 Starlink satellites in orbit https://planet4589.org/space/con/conlist.html, all coming down within 5 years.

That's an *average* of 5 or 6 a day for the next 5 years. And the v2's are bigger than the v1's. v2's are (conservatively) 1000kg and (conservatively) half aluminum. That's 2.5-3 tonnes of aluminum per day. 8 times the natural infall rate of aluminum (and there's lots of other scary things like lithium). What will that do to our atmosphere?

SpaceX is awful.

Interview 2 went much better (which is good, Saskatoon is where ...

2026-05-11T16:23:41+02:00

In reply to nevent1q…v4hc
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Interview 2 went much better (which is good, Saskatoon is where it's most likely that pieces would be found, if there are any pieces) and I remembered to say the email address I want people to send possible space junk finds to! AND I got a better camera setup and actually brushed my hair. But I'm somehow going to end up on CBC national news in my ratty farm sweatshirt AGAIN aren't I?

hahaha oh no I forgot I was supposed to be on Google Meets for ...

2026-05-11T15:55:50+02:00

In reply to nevent1q…af8n
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hahaha oh no I forgot I was supposed to be on Google Meets for this interview not a phone call! Luckily my computer cooperated and the producer was very understanding. I just am wearing a ratty farm sweatshirt and didn't brush my hair and have a messy room in the background. Oops. Luckily I've got another interview for Saskatoon in 15 minutes so I can try to do better this time...

And now time for my morning radio interview. At least I had time ...

2026-05-11T15:39:30+02:00

In reply to nevent1q…9src
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And now time for my morning radio interview. At least I had time for (most of) a cup of tea first.

It's a Good Cloud Day. But the goats are very annoyed there ...

2026-05-11T15:39:00+02:00

It's a Good Cloud Day. But the goats are very annoyed there was a teeny tiny bit of rain (they really do not like rain).

and then there's magnitudes...

2026-05-05T01:05:14+02:00

In reply to nevent1q…5fj3
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and then there's magnitudes...

I have a really nice (horrifying) image stack that one of my ...

2026-05-04T16:06:18+02:00

I have a really nice (horrifying) image stack that one of my research team members made, that powerfully demonstrates what a huge problem satellite streaks are for wide-field imaging. This is a 3 hour stack of star-subtracted 5 minute exposures using the Canada-France-Hawaii Telescope. The short diagonal lines are asteroids. The long diagonal lines are sunlit satellites that passed through the field of view during the exposure.

Just in case you also want to worry about ozone depletion from ...

2026-05-04T05:53:13+02:00

In reply to nevent1q…sh5v
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Just in case you also want to worry about ozone depletion from the gigantic experiment we're running with thousands of disposable satellites in orbit, here are some of the references I just sent to the journalist:

https://ntrs.nasa.gov/api/citations/20240013276/downloads/NASA-TM-20240013276-V6.pdf

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL109280

https://www.sciencedirect.com/science/article/pii/S0273117726003509

Currently reading/editing a draft of a reply comment a group ...

2026-05-04T05:15:44+02:00

Currently reading/editing a draft of a reply comment a group I'm in is writing to the FCC's Notice Of Proposed Rulemaking on Spectrum Abundance for Weird Space Stuff (yes, that's fucking actually what it's called) and I'm just going to congratulate myself on not throwing my laptop out the window.

The FCC is awful. https://www.fcc.gov/document/spectrum-abundance-weird-space-stuff

Barn cat and llama glamour shots. I especially like the ...

2026-05-03T18:51:07+02:00

Barn cat and llama glamour shots. I especially like the llama's hay-hat. (The barn cat is named "Devil Cat" and she's actually very sweet, but that was not the case when she was a feral kitten who showed up).

I won an astronomy communication and public education award from ...

2026-04-24T23:12:32+02:00

I won an astronomy communication and public education award from the Canadian Astronomical Society, for yelling about satellite pollution! I'm quite honoured, and now obligated to continue yelling.

Which I was going to do anyway, but it's extremely nice to know that my university (who gave me a public education award last year) and my professional society both think I am good at yelling about this and should keep doing it.

It was also recently pointed out to me by a journalist that ...

2026-04-21T20:00:33+02:00

In reply to nevent1q…kukz
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It was also recently pointed out to me by a journalist that I've been making a mistake... Starlink V2's are "only" about 1250kg, which is actually only about half a Ford F150, because Ford F150s are freaking enormous!!

Fediverse, what's a better comparison point for something that is mostly metal and weighs about 1250kg? Toyota Corolla? That makes it seem small... Something big that's not a car?

RE: https://mastodon.social/@markhurst/116443904029279313 New ...

2026-04-21T19:56:08+02:00

RE: https://mastodon.social/@markhurst/116443904029279313

New paper came out today by atmospheric chemists looking at what changes are already happening in the atmosphere due to billionaires using the atmosphere as a satellite crematorium: https://www.sciencedirect.com/science/article/pii/S0273117726003509

quoting
note1jxv…kwxz

I spoke with astronomer Samantha Lawler - Prof. Sam Lawler (npub1dgc…cla4) - about how Elon Musk has proposed to burn up in the sky one truck-sized satellite *per hour*. Unclear what that will do to the atmosphere, but it's not good.

Full episode:
https://techtonic.fm/episodes/2026-04-20-starlink-and-kessler-syndrome-feat-astronomer-samantha-lawler/

Good morning from Saskatchewan! I think my light pollution ...

2026-04-09T16:56:47+02:00

Good morning from Saskatchewan!

I think my light pollution article with Hanno Rein (npub166j…9nxq) https://theconversation.com/a-million-new-spacex-satellites-will-destroy-the-night-sky-for-everyone-on-earth-277938 must have just gotten picked up by some bigger publication, because I suddenly have an inbox full of media requests. Welcome home, I guess?

The Royal Tyrrell Museum is probably the best museum I've ...

2026-04-08T15:47:18+02:00

The Royal Tyrrell Museum is probably the best museum I've ever been to. Completely unapologetic, fully scientific presentations on evolution, Earth's history, extinction, and it even ends with a powerful statement on climate change. With the added bonus of many children (and some adults...perhaps me...) completely losing their minds over cool dinosaurs. WOW.

Definitely go to this museum if you're ever anywhere near Alberta!!

Have to try to start playing tetris to pack my car with all the ...

2026-04-05T21:34:32+02:00

Have to try to start playing tetris to pack my car with all the stuff we acquired in the last few months of travel (and decide if it's worth mailing anything to ourselves instead). And make decisions about weather and the long drive to Sask.

Given everything else that's happening, everyone needs a few more absurdly gorgeous night sky photos I took 2 weeks ago in the Tekapo Dark Sky Reserve, in the best night skies I've ever seen in my life (despite all the satellites. Sigh.)

RE: https://telescoper.blog/2026/04/03/finding-easter/ I'm an ...

2026-04-05T18:03:33+02:00

RE: https://telescoper.blog/2026/04/03/finding-easter/

I'm an astronomer, and I teach at a Catholic college (though I'm not religious myself).

I had absolutely no idea how complicated the date of Easter is. Wow.

quoting
note1ef9…a2vk

##

Finding Easter

As an Astronomist I am often asked “How do they calculate the date of Easter?”, so here goes.

The simple answer is that Easter Sunday is on the first Sunday *after* the first full Moon *on or after* the Vernal equinox. The [Vernal Equinox took place this year on March 20th ](https://telescoper.blog/2026/03/20/the-vernal-equinox-2026/ )and the first full moon after that was on April 2nd.

I say “simple” answer above because it isn’t quite how the date of Easter is reckoned for purposes of the liturgical calendar.

For a start, the ecclesiastical calculation of the date for Easter – the *computus* – assumes that the Vernal Equinox is always on March 21st, while in reality these days it is more frequently 20th March, like this year.

On top of that there’s the issue of what reference time and date to use. The equinox is a precisely timed astronomical event but it occurs at different times and possibly on different days in different time zones. Likewise the full Moon. In the ecclesiastical calculation the “full moon” does not currently correspond directly to any astronomical event, but is instead the 14th day of a lunar month, as determined from tables (see below). It may differ from the date of the actual full moon by up to two days.

There have been years (1974, for example) where the official date of Easter does not coincide with the date determined by the simple rule given above. The actual rule is a complicated business involving Golden Numbers and Metonic cycles and whatnot.

Here is an excerpt from the *[Book of Common Prayer](https://en.wikipedia.org/wiki/Book_of_Common_Prayer )* that shows Anglicans how to determine the date of Easter for any year up to 2199:

The calculations are based on the approximately 19-year [metonic cycle](https://en.wikipedia.org/wiki/Metonic_cycle ), which is why the above table will not work indefinitely

For this year we find that (2026+1=2027) ÷19=106 with a remainder of 13 (106 × 19 being 2014). The Golden Number for this year is therefore 13, or XIII in the Table. This gives the date of the [Paschal Full Moon](https://en.wikipedia.org/wiki/Ecclesiastical_full_moon ), which occured this year on 2nd April, which is indeed the day in the centre column next to XIII in the left-hand column in the table. The Sunday Letter is determined by the remainder of (2026+506+6)÷7, which is 4, so this year’s Sunday Letter is D. The date of Easter Sunday is given by the entry in the centre column next to the first occurrence of D in the right-hand column after the Golden Number XIII appears in the left-hand column, i.e. April 5th. I hope this clarifies the situation.

#astronomy #BookOfCommonPrayer #computus #Easter #Equinox #GoldenNumbers #SundayLetters

RE: https://mastodon.social/@arstechnica/116337015253122494 I ...

2026-04-05T06:23:50+02:00

RE: https://mastodon.social/@arstechnica/116337015253122494

I very much appreciate the way they wrote this: "SpaceX, which recently reported two Starlink satellite failures that created new space debris, yesterday accused Amazon and its launch partner Arianespace of negligence that 'needlessly and significantly increases risk to other operational systems and inhabited spacecraft.'”

It's too bad that 2 giant evil companies hating each other does not result in anything cancelling out, and will probably just cause more problems...

quoting
note10k4…5f7v

SpaceX claims Amazon Leo launches could crash into Starlink satellites
Amazon denies violation, says SpaceX caused conflict by lowering Starlink satellites.
https://arstechnica.com/tech-policy/2026/04/spacex-claims-amazon-leo-launches-could-crash-into-starlink-satellites/?utm_brand=arstechnica&utm_social-type=owned&utm_source=mastodon&utm_medium=social

I should add, for those who are interested and want ridiculously ...

2026-04-05T02:39:39+02:00

In reply to nevent1q…8y6s
_________________________

I should add, for those who are interested and want ridiculously cute distractions to look forward to: #BabyGoatCountdown is at 11 days!! (Plus or minus 1 day, goat due dates are pretty reliable)

I'm still very far away from my goats, but I got to see some ...

2026-04-05T02:04:45+02:00

I'm still very far away from my goats, but I got to see some cows today (and some flowers!)

Over the last few months, I experienced the following seasons in this order:
-Saskatchewan winter (very cold and snowy)
-coastal BC winter (cool and rainy)
-New Zealand summer (hot to warm)
-New Zealand fall (warm to cool)
-coastal BC spring (warm)
-in a couple of days: Sask early spring/thaw season (cold to cool, rain and snow)

Weird.

Pretty pictures here (thanks for the link, ...

2026-04-04T01:20:07+02:00

In reply to nevent1q…cstp
_________________________

Pretty pictures here (thanks for the link, [@merrdiff.bsky.social](https://bsky.brid.gy/r/https://bsky.app/profile/merrdiff.bsky.social ) !)

https://images.nasa.gov/

I have SUCH mixed feelings about the whole mission... and rockets... and I want to be excited but also fuck Starlink....

I just keep forgetting about the moon mission (too much awful ...

2026-04-04T01:14:52+02:00

I just keep forgetting about the moon mission (too much awful US-related news, and also too much life stuff happening). Looks like they're actually doing it!

The part that I'm actually excited about is the perspective of looking back at Earth from the Moon. That is COOL. I spent some time my last night in NZ looking up at the Moon, thinking about astronauts, and also tilting my head to try to understand why the moon looked upside-down to me from NZ!

Goodbye, New Zealand!! It's been a truly incredible few ...

2026-04-03T05:06:05+02:00

Goodbye, New Zealand!! It's been a truly incredible few weeks, I have learned so much. Thank you to everyone who taught me and everyone who made this trip possible. #ProfSamLectureTour

This is the highest footnote count and highest pun density of ...

2026-04-01T06:56:02+02:00

In reply to nevent1q…2pzy
_________________________

This is the highest footnote count and highest pun density of anything I've ever written. And it was WAY more fun than writing a research paper or a scicomm article!

Please enjoy reading, laugh at our puns, and then talk to your government representatives about better regulation of satellites in orbit, and accountability for their pollution!

"Using a global bovine density dataset, previously published ...

2026-04-01T06:52:46+02:00

In reply to nevent1q…z4mv
_________________________

"Using a global bovine density dataset, previously published satellite casualty probability code, and a complete lack of funding to do this calculation carefully enough for submission to a peer-reviewed journal, we calculate a ≃ 0.3–1% chance of a cow-sualty in NZ from reentering Starlink Gen2 debris over the next 5 years."

This is NOT peer-reviewed, though we wish it was! Maybe this silly cow-culation will be enough to get some government agency to fund us to do this better!

Along with ...

2026-04-01T06:49:07+02:00

In reply to nevent1q…dm2a
_________________________

Along with [@astrokiwi.bsky.social](https://bsky.brid.gy/r/https://bsky.app/profile/astrokiwi.bsky.social ) and Laura Revell, we wrote "Cow-culation: Reentry Impact Risk to Livestock in the Satellite Megaconstellation Era" https://arxiv.org/pdf/2603.29324

This all started because the three of us were writing about pollution from satellites and bemoaning the fact that there is basically no funding for this serious, rapidly growing issue. But you know what does get a lot of funding in NZ? Cows! And the joke began...

Secret hilarious project is now live! Astronomy has a fine ...

2026-04-01T06:46:59+02:00

*Secret hilarious project* is now live!

Astronomy has a fine tradition of April Fool's Day papers, where there are real calculations, but perhaps on a very silly topic.

Compilation of this year's Acta Prima Aprilia papers here: https://www.actaprimaaprilia.com/2026-issue

Follow up: I didn't read carefully. This may have been caused ...

2026-03-30T21:56:12+02:00

In reply to nevent1q…6c90
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Follow up: I didn't read carefully. This may have been caused by an internal explosion rather than a debris collision (similar to what happened to another Starlink satellite a couple months ago). So... SpaceX will make Kessler Syndrome happen even faster with their exploding satellites, I guess. Weeee

RE: https://mastodon.social/@hannorein/116319800679957972 Pew pew ...

2026-03-30T21:38:46+02:00

RE: https://mastodon.social/@hannorein/116319800679957972

Pew pew pew Kessler Syndrome here we come! (Ok yes, we're already in Kessler Syndrome, this is Kessler Syndrome: small collisions happen more and more frequently)

quoting
note1w2d…8zhm

I just gave an interview with a journalist raising concerns about Kessler Syndrom and complaining about megaconstellations in general. And less than 5 minutes later, I see a post about a starlink satellite being involved in a "fragment creation event".

Prof. Sam Lawler (npub1dgc…cla4)

FCC reply comments are due by 5pm EDT Monday 30 March on Reflect ...

2026-03-29T00:08:12+01:00

FCC reply comments are due by 5pm EDT Monday 30 March on Reflect Orbital. If you wrote in a comment, please please please write in again saying that they did not address your concerns in their letter (which is very hard to find in the FCC dumpster-fire-of-a-website). Instructions here: https://aas.org/posts/advocacy/2026/02/how-submit-comments-satellite-applications-fcc

The most horrifying part in their "consolidated reply": they agree that they could in fact cause permanent eye damage to people using medium-sized telescopes. WILD.

I got to go to an A&P show yesterday (the equivalent of a ...

2026-03-28T22:49:38+01:00

I got to go to an A&P show yesterday (the equivalent of a county/town/agricultural fair in N. America) and HOLY SHEEP. It was everything I could hope for, with the added bonus of a vegetable sculpture contest and the prizewinning alpacas (and cows and horses) marching behind the town's bagpipe band! It ended with a sheep shearing speed contest, where everyone was hanging around drinking beers and taking turns shearing sheep (the shearers were averaging 2 min per sheep. Wow.)

RE: https://mstdn.ca/@Paulatics/116295875711029533 I am so proud ...

2026-03-26T19:34:42+01:00

RE: https://mstdn.ca/@Paulatics/116295875711029533

I am so proud Senator Paula Simons🇨🇦 (npub12j4…vque) is part of my government!! Thank you for talking about this huge issue! This is such an excellent speech, and I hope this makes some sort of difference (as I'm pulling my hair out trying to help write responses to Reflect Orbital's horrifying FCC proposal for space mirrors)

Also, this speech means that I'm officially recognized by the Canadian Senate as a goat farmer and orbital dynamics expert. That's right up there with having an asteroid named after me!

quoting
note1reh…85jz

Elon Musk wants to put a million new satellites into space. Meantime, his old ones keep falling out of the sky - and landing on the Canadian prairies! This week, I rose in the Senate to launch my inquiry in the many problems caused by satellite pollution. (With many thanks to Prof. Sam Lawler (npub1dgc…cla4)) https://youtu.be/mH-FDPCtiXM?si=zOZV-GPn4qyOVkOf #cdnpoli #Starlink #SpaceX #saskatchewan #Canada

For no reason at all, please give me your favourite cow-related ...

2026-03-26T08:10:19+01:00

For no reason at all, please give me your favourite cow-related figures of speech! (Stuff like "No use crying over spilled milk" or "until the cows come home", puns extremely welcome)

Yesterday my partner and kids visited the Antarctic Centre in ...

2026-03-25T22:58:08+01:00

Yesterday my partner and kids visited the Antarctic Centre in Christchurch, and they were all delighted by the penguins and huskies. They were less impressed by the "cold room" (which was -8C and had fans that also blow wind at 40km/hr, they have parkas you can borrow...)

Saskatchewan has completely changed our standards for cold weather! My 9yo: "It didn't even freeze my boogers! That's not cold!" My partner: "It was nice dog walking weather."

Fuck. Reflect Orbital apparently had more time than we thought to ...

2026-03-25T10:13:33+01:00

Fuck. Reflect Orbital apparently had more time than we thought to respond, and they just did. We have a lot more writing to do. Hopefully some of you who wrote comments will also write and submit replies to Reflect Orbital's FCC response. I'm sure it's total bullshit, and I am not sure when I will have the strength to read it.

Fuck you, Reflect Orbital. I hate absolutely everything you are planning to do. Really tempted to submit THAT to the FCC...but I will rethink when not 100% exhausted.

The American Astronomical Society's 2nd round petition to ...

2026-03-24T18:58:27+01:00

The American Astronomical Society's 2nd round petition to deny (written by me and many others) is now published: https://pub-92a1d770e9be416e8558d475b4b5b847.r2.dev/afb0661e-408a-4b87-b72e-87c20f38b0cd.pdf

Every single section starts with "SpaceX's Opposition does not resolve the concerns raised by AAS" because they fucking didn't resolve anything (but at least they didn't openly mock astronomers like they did with Amazon a Viasat. Wild.)

Special shout-out to the fedi-person who suggested the Indianapolis 500 crash analogy, which made it in to our response!

I just proofread the American Astronomical Society response to ...

2026-03-22T23:49:10+01:00

I just proofread the American Astronomical Society response to SpaceX's response to AAS's petition to deny on SpaceX's million sat filing. It's a great document, but the fact that we need to say any of this (and spend volunteer time fighting SpaceX's highly paid lawyers) is completely infuriating.

I need to go outside now, really tough that I'm in a city and don't have a hay field available for easy rage-screaming.

And last but not least, HOLY SHIT the stars were fucking ...

2026-03-20T20:21:09+01:00

In reply to nevent1q…vtz5
_________________________

And last but not least, HOLY SHIT the stars were fucking incredible last night!!!! (No auroras visible from here but the stars were so good who cares)

(Lots of satellites, of course. Sigh.)

And it appears that Reflect Orbital missed the deadline to ...

2026-03-20T20:09:47+01:00

In reply to nevent1q…am74
_________________________

And it appears that Reflect Orbital missed the deadline to respond to the nearly 2000 comments and petitions to deny that were submitted to the FCC!!!! Thank you to everyone who wrote in!!

This is amazing. It unfortunately probably doesn't mean that they will stop the process of launching, the FCC will still consider it, and may approve it. But at least I don't have to help write a new response by like... Tuesday. Fuck you, FCC, this process is awful and stupid.

I have another email from ...

2026-03-20T20:07:48+01:00

In reply to nevent1q…jvau
_________________________

I have another email from [@planet4589.bsky.social](https://bsky.brid.gy/r/https://bsky.app/profile/planet4589.bsky.social ) saying that he's already put the brand new proposed AI data center megaconstellation on his website https://planet4589.org/space/con/conlist.html

That's now 3 new AI data center megaconstellations proposed in the last month or so, one of which has a million satellites (thanks, SpaceX. You suck.)

Thanks to many hours from many astronomers, the response to SpaceX's response to AAS's petition to deny is ready for approval, has to be submitted by Monday.

I have an email from my collaborator saying he just re-ran the ...

2026-03-20T20:03:54+01:00

In reply to nevent1q…cxvw
_________________________

I have an email from my collaborator saying he just re-ran the CRASH Clock code, and we are now under 3 days for the first time ever! Good work on bringing us that much closer to Kessler Syndrome, everybody. Special congrats to SpaceX on that one. Hope you take full credit when it starts!

https://outerspaceinstitute.ca/crashclock/ (Website hasn't been updated yet, but here's info on what the CRASH Clock tells us about how close we are to Kessler Syndrome)

WOW what a rollercoaster looking at my email and texts this ...

2026-03-20T20:02:02+01:00

WOW what a rollercoaster looking at my email and texts this morning. First piece of context: I am staying in an (incredibly nice) sheep shearer's hut (actually bigger than my house) in the Aoraki Mackenzie Dark Sky Reserve and THIS is what the sunrise looks like right now. Wow.

I presented at the local planetary journal club this morning ...

2026-03-20T01:30:36+01:00

I presented at the local planetary journal club this morning about the 3 articles I co-authored for The Conversation in the past weeks about the effects that one million satellites would have on the night sky, the atmosphere, and the orbital environment (spoiler alert: all very very bad)

https://theconversation.com/a-new-space-race-could-turn-our-atmosphere-into-a-crematorium-for-satellites-276366

https://theconversation.com/too-many-satellites-earths-orbit-is-on-track-for-a-catastrophe-but-we-can-stop-it-275430

And one on light pollution that I thought would get published today but might not be out until after the weekend.

I'm supposed to drive to the Tekapo dark sky preserve later ...

2026-03-19T21:34:06+01:00

I'm supposed to drive to the Tekapo dark sky preserve later today, to give my last (planned) talk in the #ProfSamLectureTour, but wow I am tired. It will be totally awesome, I even get to stay in a sheep shearer's trailer on a sheep station!! But... actually packing up and driving, again, after so many other trips within trips is definitely starting to get to be too much.

But it will be awesome! I just have to... make myself (and my family) pack up yet again.

Grant me the (Saskatchewan pirate?) strength to not throw my ...

2026-03-18T22:08:53+01:00

In reply to nevent1q…r20n
_________________________

Grant me the (Saskatchewan pirate?) strength to not throw my laptop out the fucking window as I try to write parts of the text for the American Astronomical Society's response to SpaceX's infuriating, arrogant, ignorant, irresponsible non-response.

Yet another Conversation article about why SpaceX's million ...

2026-03-18T20:23:34+01:00

Yet another Conversation article about why SpaceX's million satellite plan is ludicrous is approved for publishing! Will link once that's out, possibly later today but maybe not until after the weekend, depending on the editor's schedule.

I AM TIRED OF EDITING AND WRITING AND YELLING BUT I CAN'T ...

2026-03-18T03:56:52+01:00

I AM TIRED OF EDITING AND WRITING AND YELLING BUT I CAN'T STOP BECAUSE THERE ARE SO MANY THINGS I NEED TO FIGHT

-The really fun tidbit of info from today's meeting: ...

2026-03-17T22:57:35+01:00

In reply to nevent1q…dhvy
_________________________

-The really fun tidbit of info from today's meeting: apparently there are still 40 or so Soviet uranium-fueled nuclear reactor cores in orbit at about 900km altitude. Just to make any possible future Kessler syndrome even more exciting? (Maybe someone should model how likely the Kessler Syndrome collisional cascade is to reach 900km altitude... or maybe not)

A super interesting but depressing podcast about Kosmos 954 here: https://www.cbc.ca/arts/operation-morning-light-podcast-soviet-satellite-exploded-traditional-dene-land-1.6650994

-439 new objects were catalogued in orbit in the last ~month. 410 ...

2026-03-17T22:51:51+01:00

In reply to nevent1q…a85j
_________________________

-439 new objects were catalogued in orbit in the last ~month. 410 of those are Starlink satellites.
-there were 16 Falcon 9 launches, 15 of which were just for Starlink satellites
-there were 102 uncontrolled reentries, 38 were Starlink satellites
-One bigger reentry was the NASA Van Allen Probe A, which NASA issued a press release about having a 1 in 4,000 chance of killing someone. (But it didn't. Roll the dice again!)

One of the best parts of my academic committee work is that I get ...

2026-03-17T22:48:30+01:00

One of the best parts of my academic committee work is that I get regular meetings with [@planet4589.bsky.social](https://bsky.brid.gy/r/https://bsky.app/profile/planet4589.bsky.social ), who is a lovely human and has the best public database on launches and reentries https://planet4589.org/space/index.html

The worst part is hearing all the stuff that happened in orbit since the last time we met.... A few highlights from today's meeting:

-There are now 10,049 Starlink satellites above our heads. More than 1,500 have already been burned up in Earth's atmosphere.

Yesterday I borrowed a book off ...

2026-03-17T20:30:33+01:00

In reply to nevent1q…mtpp
_________________________

Yesterday I borrowed a book off [@astrokiwi.bsky.social](https://bsky.brid.gy/r/https://bsky.app/profile/astrokiwi.bsky.social )'s bookshelf written by Annalee Newitz 🍜 (npub1hhs…rl5g). Feeling slightly homesick for Saskatchewan after a few weeks in New Zealand, I was DELIGHTED to find that the book begins with "The Last Saskatchewan Pirate" https://www.youtube.com/watch?v=DuGGNsE3_8Y and I'm totally going to channel that Saskatchewan pirate energy into the talks, writing, and meetings I have today fighting satellite pollution.

Aaaarrrr, Matey! Get it? Métis?

I am feeling seriously depressed about this, and also Reflect ...

2026-03-17T20:27:01+01:00

In reply to nevent1q…pzyw
_________________________

I am feeling seriously depressed about this, and also Reflect Orbital's no doubt similarly infuriating response that's due in a couple of days. I'm not sure what I expected, I guess I'm just not cynical enough to deal with current reality yet. Kessler Syndrome, here we come!!

SpaceX's highly paid lawyers responded to the hundreds of ...

2026-03-17T19:48:37+01:00

SpaceX's highly paid lawyers responded to the hundreds of comments and oppositions submitted to the FCC in one letter, that basically shows they didn't actually read our petitions to deny. And now we astronomers and dark sky advocates who are volunteering our time have to do a shitload more work to respond to their non-response. By Friday.

Fuck you, SpaceX.

It is truly impressive how many time zone mistakes I made before ...

2026-03-16T22:30:17+01:00

It is truly impressive how many time zone mistakes I made before 9am this morning. Fuck you, daylight savings time.

Just had an excellent interview for the New Zealand Young Farmers ...

2026-03-16T02:01:29+01:00

Just had an excellent interview for the New Zealand Young Farmers podcast about farming careers, non-farming careers, why farmers are so important for dark sky access, why farmers are more reliant on Starlink than most people and how to change that, why farmers are the ones most impacted (sometimes literally) by space debris, and having good relationships with the land you live on and the sky you live beneath. That was fun!

Any journalists want to write an article about all the ...

2026-03-15T23:42:17+01:00

Any journalists want to write an article about all the environmental costs of the more than 10,000 Starlinks that are now in orbit? All I'm seeing are breathless articles mindlessly worshiping That Awful Billionaire for crossing the 10,000 satellite mark.

Every single one of those will come down in an uncontrolled reentry. That's a lot of metal in the atmosphere, and a lot of dice-rolling to see if any more pieces will make it to the ground.

SpaceX is truly awful.

Oh, and here's one from just a few minutes earlier that is ...

2026-03-14T22:32:03+01:00

In reply to nevent1q…fdvg
_________________________

Oh, and here's one from just a few minutes earlier that is full of satellite streaks 😭

(Follow up note: it was just barely visible to the naked eye, and ...

2026-03-14T22:23:59+01:00

In reply to nevent1q…nqw0
_________________________

(Follow up note: it was just barely visible to the naked eye, and just looked totally white with maybe a hint of red. A camera was required to see the colours)

I saw southern auroras last night!!!! Rakiura! Holy cow that was ...

2026-03-14T22:21:57+01:00

I saw southern auroras last night!!!! Rakiura! Holy cow that was AMAZING

(View from a bit south of Arthur's Pass, New Zealand)

Kia Ora, Nelson! (In a few hours, hopefully, I haven't left ...

2026-03-11T00:35:41+01:00

Kia Ora, Nelson! (In a few hours, hopefully, I haven't left Christchurch yet, but I'm posting now so I don't forget)

Due to unexpected very bad things last week, my lecture in Nelson got moved back by 1 week (though their website hasn't been updated, oops): https://nelsonastro.space/event/bht-lecture-astronomy-vs-the-billionaire-space-race-dr-samantha-lawler/

Same time and location, but now on Thursday March 12! Hope to see a few of you there #ProfSamLectureTour

My poll about mansplaining was mansplained to me. Deleted. Done. ...

2026-03-09T09:44:15+01:00

My poll about mansplaining was mansplained to me. Deleted. Done. Time to sign off for a bit.

Please submit your FCC comments about why you think Reflect Orbital's idea for giant mirrors in orbit is terrible. Tomorrow (March 9) is the last day to submit, instructions here: https://darksky.org/news/two-satellite-proposals-threaten-the-night-sky-the-window-to-act-is-now/

Happy International Women's Day! Women* (for my ...

2026-03-09T06:31:47+01:00

Happy International Women's Day!

Women* (for my non-scientific polling purposes, this is everyone who does not identify as a man): how many men have mansplained to you something you're an expert on in the last 24 hours? (I just blocked a ridiculous mansplaining dude, so yeah.)

RE: https://mastodon.social/@sundogplanets/116053742685475452 ...

2026-03-08T21:19:11+01:00

RE: https://mastodon.social/@sundogplanets/116053742685475452

Monday morning in NZ feeling extremely Monday (especially as it's still Sunday for a lot of the people I work with and talk to and follow here).

Trying not to fall into the despair hole. I need to refocus so I can keep fighting the fights I can make a big difference in. That probably means fighting you, Reflect Orbital, as the FCC deadline for comments is March 9 (end of day EST): https://darksky.org/news/two-satellite-proposals-threaten-the-night-sky-the-window-to-act-is-now/

Let's see where today takes me...
nostr:note127g8v89kd8lzf9mnnhyswg6v9k48xdfp7xl4m5sqy69ty6pgqzaqwqdvgp

You know what's really cool? Sociable eels in small streams ...

2026-03-08T09:05:46+01:00

You know what's really cool? Sociable eels in small streams on a university campus in New Zealand.