# Astronomy Problems PLEASE HELP! PLEASE PLEASE

okay so i was given this graph and questions and have no clue where to start! any help or tips would be great!! thanks!! if you cant really see the graph i have attached the actual paper with the graph so u can see it!

Planet M (kg) R (km) a A (AU) MStar (kg) SStar P0(bar) T0(K)
Coruscant 6 x 10'25 17400 0.1 0.44 5 x 1029 1600 1.9 295
Dagobah 1.2 x 10'24 3500 0.05 3.3 6 x 1031 1100 1.1 315
Hoth 3.5 x 10'24 9500 0.8 4.6 2 x 1030 900 0.6 168
Tatooine 6 x 10'23 2400 0.1 0.75 5 x 1030 2900 0.5 328
Yavin IV 8 x 10'25 19000 0.3 0.01 6 x 1028 1700 0.85 290

. The columns are M for mass of the planet, R for radius of the planet, a for albedo of the planet, A for distance of the planet from the parent star, MStar for mass of the parent star, SStar for Solar Flux of the star at the planet (in W/m2), P0 for pressure at the planet’s surface, and T0 for average temperature at the planet’s surface. Tatooine is technically a double-star system, but we can consider the planet to orbit around the center of mass of the two stars.

What are the densities of these planets?

What do these imply about these planets compositions?

What are their surface gravities?

How much would you weigh on these planets?

What are the periods of these planets around their parent star (or gas giant, in the case of Yavin IV) in earth years?

With the pressure and temperature shown, determine if the planet could have abundant liquid water.

Determine if the planet has a greenhouse effect. What should the temperature of the planet be without the Greenhouse effect? What might this imply about the composition of the planetary atmospheres?

#### Attachments

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## Answers and Replies

mgb_phys
Science Advisor
Homework Helper
Would you like to make an attempt at some of the questions?

i just dont know the formulas or else i would.... thats what i need help on mostly

mgb_phys
Science Advisor
Homework Helper
What are the densities of these planets?
I'm sure you can find the formula for the volume of a sphere.
Then density is just mass/volume

What do these imply about these planets compositions?
Are rocks denser than water? Is gas less dense than water?

What are their surface gravities?
You are looking for an equation for gravitational force on a mass, at a distance = radius of the planet.

How much would you weigh on these planets?
Once you have found 'g' in the above question then weight is just = m g