Coordinate system Flashcards
1
Q
Give 3 different coordinate systems
A
- geocentric-inertial frame
- heliocentric-inertial frame
- geographical body-fixed system
2
Q
what does body-fixed mean
A
measures motion relative to that body
3
Q
what does inertial frame mean
A
referenced to stellar position (vernal equinox is primary reference)
4
Q
What is vernal equinox
A
- 2 days in a year when Earth is located at the intersection of the equatorial and ecliptic planes
- spring and autumn
5
Q
How do geocentric and heliocentric inertial frames differ
A
geocentric - uses Earth as the centre
heliocentric - use Sun as the centre
6
Q
Describe geographical-body-fixed coordinate system
A
- 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
7
Q
What 3 things are required to describe spatial position of an orbit
A
- inclination, i
- argument of periapsis, w
- longitude of the ascending node, Ω
