# Astronomy Problems:

1. Oct 24, 2005

### astronomystudent

I don't even know how to begin these problems. If someone could leave me tips or formulas or anything to help me solve these it would be greatly appreciated. Here are the following:
1. What is the diameter (in Kilometers) of Mars if it appears 18 arcsec in sized when it is 0.520 AU from Earth?

2. What is the focal length of the Meade 12 inch LX200 (12 inch x 25.4 mm/inch aperture) when it is used at f/5.86? How would a 15 sec exposure at f/5.86 compare to an exposure at f/20? What would be the pixel resolution for a 9 micron pixel at f/5.86?

3. What is the rotation period of Io (in days) if it is in a 1:1 resonance with Jupiter like our Moon is with Earth. Jupiter has a mass of 318 M(earth). Io's mass is insignificant and it has a semimajor axis of 421,600 Km. Remember you must use EMDs and lunar sidereal months with Earth masses or change to Solar masses, years and AUs!

4. If the diameter of a new Kuiper object was found to be 1/10th the diameter of Earth and its mass was 1/3000th of Earth, what would its density be (in g/cc or kg/m^3).

5. If a new asteroid has a period of exactly one year, but an eccentricity of 0.25, wherer are the aphelion and perihelion points (in AU).

6. What woul be your weight on a planet with a mass of 5.67 times the mass of the Earth and a radius of 13,456 km? What would be the density of this planet?

2. Oct 24, 2005

### fasterthanjoao

if I don't say it, someone else will.... it'll really help your chances of getting helpful responses on these forums if you show at least some working or at least describe which parts it is that you don't understand, for instance; you're asking for formulas, but surely your lecture notes contain most things you need to know?

(i'll be on later and i'll give some of those questions a bash, seems like level 1 undergrad to me?)

3. Oct 24, 2005

### fasterthanjoao

if I don't say it, someone else will.... it'll really help your chances of getting helpful responses on these forums if you show at least some working or at least describe which parts it is that you don't understand, for instance; you're asking for formulas, but surely your lecture notes contain most things you need to know?
(i'll be on later and i'll give some of those questions a bash, seems like level 1 undergrad to me?)