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Feb
11
answered Have Sterling Engines Been Used In Outer Space?
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
answered Why don't any of the gas giants have moons of Earth's mass (or greater) that orbit them? Is this generalizable to exoplanet gas giants?
Feb
3
comment How far into space does one have to travel to see the entire sphere 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.
Feb
1
answered Is it safe to observe the sun through binoculars with welding glass in front?
Feb
1
answered Automated telescope system
Jan
31
comment How far into space does one have to travel to see the entire sphere of earth?
there you go - think my geometry is right
Jan
31
answered How far into space does one have to travel to see the entire sphere of earth?
Jan
27
answered Is it possible that I just saw Jupiter's moons?
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
25
answered How bright are auroras (aurorae)?
Jan
23
answered sun-moon-earth anomaly
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.
Dec
6
awarded  Critic
Dec
6
awarded  Citizen Patrol