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Questions tagged [horizon]

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55 votes
9 answers
11k views

Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
Jonathan's user avatar
  • 4,381
21 votes
2 answers
2k views

Are there any galaxies which fell out of sight horizon due to cosmic expansion?

If farthest galaxies run away from us with acceleration making them exceed speed of light, we should expect them to disappear from sky among time with increasing quantity. Did we observe this? Can we ...
Waldemar Gałęzinowski's user avatar
15 votes
3 answers
13k views

Would time go by infinitely fast when crossing the event horizon of a black hole?

If you were to fall into a black hole, my understanding is that from your reference point, time would speed up (looking out to the rest of the universe), approaching infinity when approaching the ...
Jonathan's user avatar
  • 4,381
10 votes
2 answers
755 views

Can moon set after being up when due north? (pseudo circumpolarity)

I'm in the northern hemisphere, facing north, and notice that the moon is due north (azimuth 0) and is still above the horizon, albeit barely. Does this mean the moon is necessarily circumpolar (...
user avatar
4 votes
1 answer
384 views

The furthest horizon in the Solar system

Where can I observe the furthest horizon in the Solar system ? And what the length of it ? The furthest horizon on Earth can be observed from mount Everest ~ 336 km, On Mars - from mount Olympus ~ 386 ...
user3715778's user avatar
15 votes
1 answer
3k views

Why does the Moon seem larger when it is close to the horizon? [duplicate]

I've noticed that when I look into the sky at night, sometimes the moon appears very large near the horizon. Sometimes it also looks like it has a yellow tint. Is this the light rays bouncing off ...
Timtech's user avatar
  • 1,685
5 votes
2 answers
268 views

Can Mercury be seen from the 60th parallel north on Earth? Shetland, Faroe, Norway, St Petersburg, Alaska

I'm originally from a city in Spain which is 40 degrees north, and I used to watch Mercury (naked eye and telescope) every time I had the opportunity, that is, when Mercury was at maximum elongation ...
we'll see's user avatar
  • 325
3 votes
2 answers
229 views

Is there any formulae to calculate whether the sun will depress 18 degrees or more below the horizon on a certain day / location?

I'm trying to code a piece of software which will calculate some times for me that would greatly help me in my day to day but none of my formulae work if the sun doesn't go at least 18 degrees below ...
15150776's user avatar