Linked Questions

1 vote
2 answers
2k views

Does the Sun's atmosphere have a scale height?

Much of the Earth's atmosphere has a scale height $h$ of roughly 7 to 8 kilometers such that the local density varies as $\exp(-(r-r_0)/h)$ where r is the radius vector and $r_0$ would be some ...
uhoh's user avatar
  • 31.3k
6 votes
1 answer
1k views

At what depth below the Sun's surface does the density reach that of water?

I'd like to write a short supplementary answer to A probe floating in Sun's surface but in order to do so I need to know at roughly what depth relative to the Sun's surface the mass density reaches 1 ...
uhoh's user avatar
  • 31.3k
3 votes
3 answers
645 views

Is it ever possible to see Earth's shadow on other planets?

Is it ever possible to see Earth's shadow on other planets? How would the shadow present, and what would be the magnification, equipment, or other conditions necessary to see it? Is there any way of ...
ErikE's user avatar
  • 143
3 votes
2 answers
410 views

How to understand exactly why gravity darkening happens on rotating stars?

Phys.org's TESS delivers new insights into an ultrahot world links to KELT-9 b's Asymmetric TESS Transit Caused by Rapid Stellar Rotation and Spin–Orbit Misalignment (readable in arXiv) The assymetric ...
uhoh's user avatar
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4 votes
1 answer
594 views

Calculate how far we could see through Earth's atmosphere if it had the opacity of the solar photosphere?

I've newly started studying astrophysics. There is a question in the book "An introduction to modern astrophysics" by W. Carroll: Calculate how far we could see through Earth's atmosphere if ...
M.Ramana's user avatar
  • 143
4 votes
2 answers
636 views

Precision in the measurement of the distance to the Sun

How precisely can the distance to the Sun be measured? Wikipedia says the distance to the Moon can be measured upto millimeter precision. But Wikipedia article on distance to the Sun says only about ...
Youngsub Yoon's user avatar
4 votes
2 answers
194 views

Accuracy of Mercury transit calculations

What is the error range for calculations for the time of 1st-4th contacts for a given GPS coordinate on Earth? I observed through a telescope the 3rd and 4th contacts and compared against SkySafari ...
Automaton's user avatar
3 votes
1 answer
146 views

How is a planet (or star's) radius defined?

The radius of a rocky planet like earth is fairly easy to define based on the fact that the ocean's surface is fairly smooth, and it is a natural point to measure. Other planets like Mars, the surface ...
Fraser Orr's user avatar
6 votes
0 answers
127 views

Source of information on density profile of a red giant star?

Is there a good source of information of the expected density profile inside a red giant star? I have read that when a star such as the sun has converted much or most of the hydrogen in its core into ...
PAUL MILENKOVIC's user avatar
3 votes
0 answers
113 views

Density of a sunspot compared to the surrounding photosphere?

Is the density of a sunspot different by more than a factor of ten compared to the area surrounding the sunspot?
Bob516's user avatar
  • 1,447