Questions tagged [angular-diameter]
For questions regarding the angular diameter of astronomical bodies
44 questions
0 votes
2 answers
133 views
Why don’t we observe the stellar wobbling of the Sun?
If one calculates the location of the center of mass of the Sun-Jupiter system, they obtain that the CM is about $1.06\ R_\odot$ away from the center of the Sun, so it lies above the solar surface, ...
- 1
5 votes
0 answers
161 views
Accurate angluar diameter calculations of the Moon and the Sun
I'm looking for two accurate calculations for the perceived angular diameter of the Moon and the Sun, for a given observer (of known latitude and longitude) at a given moment in time (UTC). I ...
2 votes
0 answers
195 views
Two Suns vs Two moons in the Sky
How rare is it to have 2 stars or 2 celestial bodies at least as big as our moon and sun in the sky of a habitable planet? What are the chances of both?
3 votes
3 answers
436 views
About angular diameter, parallax and image of the nearest neutron star RX J185635-3754
I have a big doubt about our allegedly nearest (X Ray isolated) neutron star, also known as the Walter star, one of the members of the "Magnificent Seven stars": RX J185635-3754. So I came ...
- 201
2 votes
0 answers
103 views
Angular diameter and length of baseline
How did they determine the angular diameter, please? How to predict the baseline length with the first lobe? Thank you. https://www.chara.gsu.edu/public/basics-of-interferometry If they are ...
- 783
1 vote
1 answer
133 views
Visible angular size
Is it true that given two celestial objects of the same size and at the same distance, the fainter one will appear smaller? Is there a calculation that can be made about how smaller? Is it the same ...
- 11
3 votes
1 answer
111 views
Angular size of an object falling into a black hole
People often say that an object freezes over a black hole’s event horizon as it falls in. This is because only a finite amount of proper time passes for the object before it crosses the event horizon. ...
- 31
2 votes
0 answers
138 views
When Only 50% percent of the sky will be filled with stars?
Answers to Approximately what percent of the sky has nothing in it? seem to suggest that with enough depth, we will finally hit something hence the sky is basically 100% full for any given resolution. ...
- 1,715
20 votes
5 answers
5k views
Approximately what percent of the sky has nothing in it?
From my persepective here on Earth, the sky seems to look like a few large-ish things and a bunch of tiny things. Hubble teaches us that even the apparent void between the tiny things has many very ...
- 337
9 votes
2 answers
3k views
What would Betelgeuse look like from Earth if it was at the edge of the Solar System
If we parked Betelgeuse just outside the Solar System, how big would it look from Earth?
- 388
1 vote
0 answers
192 views
What is the brightness and size of Jupiter from the Galilean moons, the closest moon, and the farthest moon?
From the Moon, Earth would appear 4 times larger than the Moon seen from Earth, and the magnitude of a "full earth" is around -17. However, Jupiter from the Galilean moons appear much larger ...
3 votes
1 answer
171 views
Minimum redshift for galaxies receding $\geq c$ when light transmitted
What is the minimum redshift for galaxies receding $\geq c$ when light was first transmitted that are visible today from Earth? Is that value the same as maximum angular size distance? This question ...
- 181
17 votes
4 answers
3k views
Can the Earth be seen from the moon when we have a total lunar eclipse at the perigee?
We know that the Moon doesn't have an atmosphere; thus the sky is seen dark. Also, from this question, the angular diameter of the Earth viewed from the Moon is a bit bigger than $2^\omicron$ at the ...
- 1,359
21 votes
2 answers
5k views
Where in space would the Earth and Moon appear to be the same size?
If I'm directly in between the Earth and Moon, what distance from the Earth would I have to be so that the Earth and Moon have the same apparent size? How big would the moon appear compared to it's ...
- 624
4 votes
3 answers
954 views
Understanding conversion to angular diameter
I was trying to better understand the concept of angular diameter and was hoping for some clarification. Given some object's coordinates in RA and dec, is it possible to find that object's angular ...
