# Tagged Questions

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2answers
215 views

### How do we measure distance using parallax?

This is a quick mock-up of how stars are measured using parallax method. My question is : How on earth (literally) do we measure the anfle $\theta$? Is theta measured from the zenith of Earth? ...
0answers
43 views

### Perturbations of planetary Orbits

I have, for years, been an Astronomy and physics nerd. For the first while, I was a total astronomy nerd. Then I slowly transitioned into physics and have been, for less than a year, a physics nerd. ...
2answers
6k views

### Converting between Galactic and Ecliptic coordinates

I was hoping someone would be able to tell me the formula to convert between ecliptic and galactic coordinates. I've been able to convert values using http://lambda.gsfc.nasa.gov/toolbox/tb_coordconv....
2answers
2k views

### How does one measure Earth's speed of revolution around the sun?

I know that there are several formulae that one can plug numbers into to arrive an estimate of Earth's speed around the sun (Kepler's third law for instance), but I'm wondering how these things are ...
0answers
168 views

### Calculating distance to an asteroid on a given day

I'd like to calculate the distance between the Earth and an asteroid at a given date. Is this possible using the data from JPL's small-body database? Is there a better way?
1answer
701 views

### Reverse Sun position algorithm?

To find the sun's position (elevation, azimuth) we can use many algorithms including the PSA algorithm. These algorithm share the fact that the input is the local time, longitude and latitude and the ...
6answers
413 views

### Given a photo of the Moon, taken from Earth, is it possible to calculate the position of the photographer's site?

Given a photo of the Moon, taken from Earth, is it possible to calculate the position (Earth longitude and latitude) of the photographer's site? I am thinking about photos taken with a normal camera ...
1answer
353 views

### A method to estimate the relative magnitude of a star using nearby stars

I remember a method to make a reasonable estimate of the magnitude of a given star X by using two other stars of known magnitude as references. The method used evaluation phrases like "the star X and ...
3answers
10k views

### How are Cepheids used to evaluate their distance?

Cepheids are used to evaluate distances. What is the math and physics behind their use?
1answer
681 views

### IRIS alternative on mac?

I need to process some images taken from a telescope to determine the intensity of an astroid. This way I can determine the rotation period of this asteroid. The pictures were taken the usual way (...
2answers
24k views

### How is distance between sun and earth calculated?

How has the distance between sun and earth been calculated? Also what is the size of the sun?