2,370 reputation
923
bio website infosecfrog.blogspot.com
location Scotland, United Kingdom
age 42
visits member for 3 years, 1 month
seen Apr 11 at 17:18

Apr
28
comment Why are there more vertical takeoff than horizontal for spacecrafts?
Yes, but they couldn't do it successfully, which is why it is only recently beginning to work.
Apr
28
comment Energy and Matter
I really think this needs to go to Physics - especially with the imminent demise of Astronomy. The physics guys would be able to give very straightforward answers on the interchangeability of energy and matter.
Apr
24
comment Why can't dark matter be black holes?
I removed the deliberately over the top artists impression :-)
Apr
11
comment Do the stars imaged by a telescope even exist at present?
@Carl - I want to know about the other missions - the ones aimed at stars :-)
Mar
12
comment What is behind the cosmological horizon barrier?
Just checked your profile and realised you certainly know the maths in much greater depth than I - so I am more than happy to believe that 2 is more likely :-)
Mar
12
comment What is behind the cosmological horizon barrier?
Option 1 or 2 both seem more likely than 3. The tricky thing is that the models could allow any of them to be true. Inflation can work as viewed for option 1 as easily as option 2.
Mar
11
comment Can you damage your eyes viewing Venus?
Additionally, the OP probably only felt like they had arc-eye as their eyes were accustomed to the dark, and the contrast from Jupiter to Venus that night may have been a bit of a jump. It takes your eyes a while to adjust to changes in light level at night as your pupils are wide open.
Mar
2
comment How can I determine if my telescope mirror is parabolic?
Thanks for those links - really interesting!
Feb
28
comment How is it that some nebulae are rotating and others are not?
I think you have partially answered your own question. There are all sorts of motion from very large to very small scale. The probability of the sum of these resulting in a net zero rotation is low.
Feb
4
comment Why is 1 AU the distance between the Sun and the Earth?
I think it does involve the earth as one of the two involved bodies. The other end of the 1AU line is at the sun.
Feb
3
comment How far into space does one have to travel to see the entire face of earth?
according to Wikipedia, as linked by FrankH above, yes
Feb
2
comment The Moon during the day
Earthshine is not what makes the moon visible during the day - it is the sun's rays reflecting off the moon that make it visible. Earthshine is what lets you see (dimly) the dark areas of the moon at night
Feb
2
comment The Moon during the day
@YUASK - it is more visible when full than when new, but also, 50% of the time you can't see it in the sky during the day because it isn't in the sky at all, but round the other side of the world.
Jan
31
comment How far into space does one have to travel to see the entire face of earth?
there you go - think my geometry is right
Jan
25
comment How bright are auroras (aurorae)?
@KeithThompson Yup - lovely crackling and fuzzing noise!
Jan
25
comment How bright are auroras (aurorae)?
sadly, at 21 N, I don't think you're ever going to see one...unless something really big happens on the Sun
Jan
21
comment sun-moon-earth anomaly
I have never seen that effect - I need to check again in case my memory is flaky, but I always showed people that if they follow that perpendicular line they will hit the sun...
Jan
2
comment How can we know, today, that there's something from 100 light-years from here?
@TomBrito - but we can tell which ones are the same or similar.
Dec
7
comment How can we know, today, that there's something from 100 light-years from here?
If you look at a car in the distance, what you are seeing is light that has travelled from it to your eye. We can work out how far it must be by comparing how small it looks against other cars. There are similar techniques to compare a distant star to others that look similar.
Oct
13
comment Parallax Cloud Displacement - Angular Distance from Geostationary Satellite
If this doesn't get an answer here, I'm guessing math.stackexchange.com could rustle one up for you pretty easily