35268 So what's the worst shock: being hit and ejected into space from Earth, or hitting the lunar surface? Good question. I don't think it's an easy answer. I expect both are pretty bad shocks, and going from Earth to Moon is worse on both sides than going from Moon to Earth, since the Moon lacks ...

The Apollo 14 astronauts might have found an Earth meteorite on the Moon.

Terrestrial-like zircon in a clast from an Apollo 14 breccia

Also a good paper to read: On the Survivability and Detectability of Terrestrial Meteorites on the Moon.

35258 Wat, is there a special term for meteorites that came from Mars or the Moon?   I remember a very famous one from Mars was discovered in Antarctica! Not really, just Martian meteorite and lunar meteorite. I've heard the latter as "lunaite" sometimes, which is cute but I think not oft...

35255 are those tektites?! No,  tektites are glass-like blobs of material that was melted and ejected by impacts occurring on Earth, so they are made mostly of Earthly materials. I have an impact generated glass ( Libyan desert glass ), which might be called an "impactite", but no tektite...

Further images of the "Promethean Fire" plasma effect, which changes over time as the gas mixture breaks in. Especially in the last month, the tendrils have slowed down dramatically, grown fuzzier and more colorful, creating gently waving ghostly structures like flowers or trees. It's been...

It's been a long while, but I've saved up and recently added a few new meteorites to the collection. I'm very excited about these ones! First is a piece of lunar meteorite NWA 11474. https://i.imgur.com/Qh00JwE.jpg Yes, this is a  rock from the Moon , with a fascinating history.   It is a breccia, o...

35218 Do you know the reasoning behind prioritising the young?  They are the most social age group, so if the idea is to achieve general immunity, it makes sense.  I'm not certain of the federal government's reasoning, but if I had to guess or give my own reasoning, I think it's exactly what you sa...

35216 Who should get it first, and how many? In the US the plan (as I've seen it presented thus far) appears to be: Phase 1: Emergency responders and health care workers Phase 2a: Those with multiple high risk factors Phase 2b: The elderly (65 and up) Phase 3: The young (30 and under) Phase 4: Ever...

35209 Didn't the 1918 pandemic also have three waves? https://i.imgur.com/L77d0k3.png COVID-19 thus far seems to have a seasonal cycle just like 1918's H1N1, which is not terribly surprising. But it's also important to recognize that these waves are not simply due to factors outside of our control,...

35205 But death rates lag behind and it may be too early, and a lot more people get tested this time.  Yeah, I think it's still a little too early. The page was last updated October 30th. New cases in the northern hemisphere were surging then, and deaths are still catching up in many places. The da...

Another analysis from the New York Times. The headline/conclusion is completely unsurprising, but the data and animated graphics demonstrating it are very nicely done. 

States That Imposed Few Restrictions Now Have the Worst Outbreaks

The US is recording over 2000 COVID-19 deaths per day again... a rate we have not seen since spring. https://i.imgur.com/WiTO4vT.png Considering the roughly 2-week lag between new cases and deaths, our case fatality rate is now about 1.5%, so our current rate of about 170,000 new cases a day implies...

Beautiful! I love how we did this completely independently. :D And yours does  clearly show how observers who are not very close will hear the sound from the supersonic flight first, which wasn't obvious. I also learned something interesting by doing this. I always imagined that if a plane suddenly ...

35154 This could probably be effectively visualised in an animation Always wanted to do something like that, so why not. :) I'll put up three different scenarios for comparison. For starters let's generate a typical Mach cone. A constant-frequency source passes by at 1.5 times the speed of sound. T...

35141 There is a similar sound heard in the Mythbuster cement truck explosion, which I'm not sure how to explain.  Hahaaa, that episode was so great. I'd completely forgotten the sound. Very weird. For fun, I plotted its spectrogram: https://i.imgur.com/MG3Flp6.jpg The downshift in frequencies is q...