All Questions
30
questions
-1
votes
1
answer
58
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How exactly did Harrison's chronometer circumvent the impulse problem of time-keeping on a moving ship?
According to folklore, around the time of the exploration of the New World, there was a quandary regarding how to measure time on the open sea. Time keeping then was based on the pendulum clock, which ...
- 179
3
votes
3
answers
329
views
Comparison of clocks running at different heights in a gravitational field
I hope this question has not yet been asked. If so then please link me to the answer.
If I build an apparatus which, on flicking a switch, sends a light beam, a distance to a mirror, and reflects it ...
0
votes
0
answers
31
views
If I levitate at the same place will I come back to the same place after Earth taking it's one complete revolution? [duplicate]
so i have this question if i mean if we can levitate and decide to levitate and not stay on ground but at a place to look the ground, and we that earth rotates right and we rotate along with it cause ...
4
votes
3
answers
410
views
How would it be possible to measure the day's length for the past?
According to this recent article [1], Earth spins faster now than in the past, switching its trend.
Besides the main focus of the above-mentioned article, what captured my attention was the knowledge ...
- 219
3
votes
1
answer
152
views
Why is the slowest point of Earth's rotation in the middle of the year?
The following image is taken from Wikipedia's article on the leap second.
Why is the slowest point each year in the middle of the year around July? Does being further from the Sun cause the Earth's ...
- 870
0
votes
0
answers
72
views
How long would it take for down becoming the opposite on earth?
Sorry if the question is unclear, I will try to explain it better.
Let's say that I am standing still somewhere on the planet and I say while pointing at my feet :"Down is this way", how ...
- 261
17
votes
1
answer
2k
views
Is Earth’s rotation slowing down or speeding up?
Section ‘Slowing down of the Earth’ of the Wikipedia article Leap second has the following paragraphs:
A mathematical model of the variations in the length of the solar day was developed by F. R. ...
- 271
0
votes
1
answer
81
views
What are the sources of error in the formula I derived to estimate sunrise and sunset times, and how can I improve its accuracy? [closed]
I derived the following formula to estimate sunrise and sunset times:
$$ t=\pm\cos^{-1}\frac{\sin\theta-\sin L_{loc}\sin L_{sun}}{\cos L_{loc}\cos L_{sun}} $$
$L_{loc}$ is the local latitude
$L_{sun}$...
- 101
2
votes
1
answer
403
views
How big (in meters) could the difference be between ECI and ECEF coordinates at midnight UTC?
Is the only difference due to leap seconds, etc. or other differences between UTC and updated forms of universal time, such as UT1? In other words, are all earth-centered inertial (ECI) coordinate ...
- 145
21
votes
7
answers
5k
views
Finding how much time it takes for a complete Earth revolution around the Sun
Long story short, my brother made a joke about how stupid it is to celebrate the Earth making one "trip" around the Sun: New Year's Eve.
So I got curious and was wondering: how could the first ...
- 320
20
votes
4
answers
14k
views
How can a day be exactly 24 hours long? [closed]
The longest solar day of year is approximately 24 hours 0 min 30 seconds (occurs at mid to late December) while the shortest solar day of year is approximately 23 hour 59min 38 seconds. If I average ...
- 1,005
0
votes
3
answers
65
views
Since astronomers are adding 'leap seconds' to our years nowadays, does that mean Earth's orbital period is getting longer?
How long was an Earth year several billion years ago? (I'm assuming constant days, even though I know days were much shorter back then).
- 4,509
0
votes
3
answers
268
views
Special Relativity and Time Dialation
I have trouble understanding why time dilation occurs for objects moving towards you at no angle.
There are two example in my physics textbook:
A woman is on a moving train holding two light bulbs ...
- 1
5
votes
2
answers
350
views
What is the easiest way to prove that the earth is more than 10000 years old? [closed]
How do you prove the earth is old in the easiest way possible? If you decide to go with atom decomposition, you have to also be able to show the decomposition rate and the exponential law which ...
- 159
3
votes
2
answers
58
views
How long do you have to wait outside of the orbit of the Earth for desired location to be right below?
My father had a (very theoretical) idea of a transportation system, where shuttle would be shot directly up from the Earth, it would stay still in the space for so long that the destination would be ...
- 131