Astrophysicist and planetophysicist, professor at Arizona State University. Fan of sci-fi, eighties music, running, and Scrabble, but who isn't?
Sep 1, 2023 • 21 tweets • 5 min read
Since so many have asked, here’s my hot take on the spherules Loeb found and the manuscript he’s loudly rushed to the world. These are pretty typical cosmic spherules. Had he done the *obvious*--a control sample 100 km away from the meteor--he’d have found the same thing. 1/20
To claim these spherules were interstellar one must establish: 1) the 2014 meteor was interstellar; 2) it didn’t burn up completely; 3) debris was concentrated where they looked; 4) the spherules came from THAT meteor; AND 5) a solar system source is ruled out. 2/20
May 24, 2021 • 5 tweets • 1 min read
btw glad to meet you! Yes, multiple asteroid taxonomic classification schemes don’t help! But that screenshot does, thanks! For these purposes any asteroid that deposits “carbonaceous chondrite” material (54Cr, etc.) counts, so I think ”C” = C plus B, P, D and some X.
These comprise >10%, and “C” types are even more common among Chicxulub-size 5-20km asteroids throughout the belt (deMeo & Carry). Bottke+07 said 30% of asteroids like Chicxulub hitting Earth are “carbonaceous chondrite”, and 40% of those (~10% of all) were CM2 specifically.
May 22, 2021 • 16 tweets • 3 min read
So I guess I’ll comment on the SL21 paper and their latest non-refereeable comments on arXiv. The whole point of SL21 is to say a comet is quantitatively more likely than an asteroid. Not to introduce the idea of a comet, that was done in 1984. Not to suggest a comet could 1/n
break up so fragments are more likely to hit Earth, that idea is in Bailey et al. 1992, which they cite but fail to acknowledge. Not to say maybe a comet could be more likely depending. No, their conclusions and press release demand a comet IS more probable than an asteroid. 2/n
