Coordinate system

Question 1

Give 3 different coordinate systems

Answer 1

1. geocentric-inertial frame
2. heliocentric-inertial frame
3. geographical body-fixed system

Question 2

what does body-fixed mean

Answer 2

measures motion relative to that body

Question 3

what does inertial frame mean

Answer 3

referenced to stellar position (vernal equinox is primary reference)

Question 4

What is vernal equinox

Answer 4

• 2 days in a year when Earth is located at the intersection of the equatorial and ecliptic planes
• spring and autumn

Question 5

How do geocentric and heliocentric inertial frames differ

Answer 5

geocentric - uses Earth as the centre

heliocentric - use Sun as the centre

Question 6

Describe geographical-body-fixed coordinate system

Answer 6

• z axis is the Northern polar axis
• prime meridian is circle between Earths poles and Greenwich
• x axis is line intersection between prime meridian and equatorial plane

Question 7

What 3 things are required to describe spatial position of an orbit

Answer 7

• inclination, i
• argument of periapsis, w
• longitude of the ascending node, Ω