Burnt by the sun (Hollywood inspired question)

Factual Questions
1

So, Deep Impact was on TV this morning, and the quality of the movie aside, I scoffed at a particular bit, but have had second thoughts, that, maybe I’m being too harsh.

I think I can do this without spoilers given the age of the movie, plus I’m not giving away major plot points.

So a point is reached where the astronauts were on the comet and the comets rotation places them on the sunny side’ of it, in the full face of the sun. One of the astronauts doesn’t get his reflective visor down in time, and if the movie is to be believed, he is essentially permanently blinded and gets what looks to be 3rd degree burns on his face.

I chuckle and say BS, but what would be the effect on an ‘unshielded’ person in the full face of the sun, unprotected by an atmosphere, etc. From memory the comet was a few days from Earth at that stage, as far as distance from the sun goes. Also in the movie the comet was portrayed with a quite marked coma and tail, wouldn’t that have provided some serious protection from the sun down on the surface of the comet?

As a secondary question, the comet was ~7miles long, would it have had any humanly discernible gravity, even standing on its surface?

2

Just a WAG, but considering that the effects of gravity seemed to have been considerably diminished for the astronauts on the moon, I doubt they’d be able to stay on from gravity alone. Maybe it could hold them there at rest, but if they jumped I think they’d be screwed. Maybe their shoes had spikes or sticky stuff. : )

3

I looked into the burning question for a while, but couldn’t find any good cites.

What I did find:

  • The atmosphere blocks out about 97% of solar UV
  • Solar UV in space can cause severe sunburn
  • Staring at the sun, even through an atmosphere, can cause significant retinal damage
  • Whether the damage will occur in just a few seconds isn’t clear
  • Spacesuit helmets are shielded, partially to block out harmful solar radiation

So eventually there will be irreversible damage, but how much and how quickly is uncertain…

4

You might notice the gravity if you were very still and paying close attention, but probably not if you’re out and about and busy wrangling nukes into position. That’s easily small enough that you could jump at escape speed, if you weren’t careful. Incidentally, note that when the craft is “landing”, they shoot out harpoons to tether the surface: That’s one of the many places in the movie where they actually paid attention to the science advisor.

And the astronauts on the Moon didn’t need anything more than a permanent tinting on the glass of their helmets to protect them from the Sun-- No need to make things more complicated with a movable visor. I’m not sure about the timing, though: Was that really only a few days before impact? Because if it was longer than that, they might plausibly have been much closer to the Sun.

5

IIRC it was the glare from the comet’s ice which was the issue.