Prof. Sam Lawler16h ago

RE: https://fosstodon.org/@AkaSci/116359971598652059

Spent all day driving through gorgeous mountains towards home, now trying to catch up on Artemis stuff so I can talk about it at stupid-o-clock in the morning on live Saskatchewan radio tomorrow morning (I'm baaack. Apparently).

Thanks to @AkaSci for a great summary of the closest approach!

The absolutely coolest detail (to me): the astronauts could SEE flashes from meteors hitting the surface?!! From 4,000km away?! (And they want to build a moon base???) Lots to think about, wow.

Show threadMichael Busch16h ago

@sundogplanets

I would like to see the recordings of those flashes.

Because the cameras will tell between actual impact flashes and phosphenes from cosmic ray hits.

Show threadAmin, minor deity of the legume realm8h ago

@michael_w_busch @sundogplanets

Oh, wow, excellent point.

Show threadMichael Busch8h ago

@amin @sundogplanets

Nearly all astronauts report seeing phosphenes in the dark when they are not paying attention to something else: https://pubmed.ncbi.nlm.nih.gov/16676658/ .

But any given cosmic ray will hit just one camera or eyeball, while actual flashes will show up in everything looking in the right direction.

Phosphenes in low earth orbit: survey responses from 59 astronauts - PubMed

Comparisons with earlier studies of light flashes in space and several ground-based studies during the 1970s are made. One interesting observation from this is that it seems that a small fraction of the light flashes is caused by Cherenkov radiation, while the majority is probably caused by some kin …

PubMed
Show threadAmin, minor deity of the legume realm

@michael_w_busch @sundogplanets

Sure! I wonder, though, if phosphenes might be differentiable from what they're describing. I presume the impacts would appear to be on the surface of the moon, while I would imagine phosphenes to look more obviously like something occluding the vision? Having not experienced them, of course, I have no idea. :)

1:52pmWeb
Show threadMichael Busch7h ago

@amin @sundogplanets

Phosphenes from particle hits in the eyeball look like brief white streaks; rather than the larger effects that happen from hitting the nerves with electromagnetic interference.

Or so I am told by biophysicists I know who get to play with medical scanners.