- Practical Exercise 1 RADIANS OR DEGREES?
- Practical Exercise 2 MARS IN OPPOSITION AND QUADRATURE
- Practical Exercise 3 MEASURING MERCURY AND VENUS
- Practical Exercise 4 “MERCUAN”
- Practical Exercise 5 THE EARTH FROM MARS
- Practical Exercise 6 HOW BIG IS THE MOON?
- Practical Exercise 7 THE MOON AGAIN
- Practical Exercise 8 PARAMETERS OF PLANET TRAJECTORIES
- Practical Exercise 9 LIKE FROM ANOTHER PLANET...
- Practical Exercise 10 FEET FIRMLY ON THE EARTH...
- Practical Exercise 11 GREEK, HOW BIG IS THE EARTH?
- Practical Exercise 12 THE MOON IN ACTION FOR THE THIRD TIME
Practical Exercise 5: THE EARTH FROM MARS
Calculate the angular distance of the Earth from the Sun from the point of view of an observer on Mars. You know that the sidereal orbital period of Mars is 687 Earth days.
Answer:
T♂ ≐ 687days ≐ 1,88 years. We start from the 3rd Kepler’s law T♂ ≐ 687days ≐ 1,88 years. We start from the 3rd Kepler’s law a'♂ = 
≐ 1,52 au. From a similar geometry as in Figure 1 (only we calculate for Mars instead of the Earth) we get: T♂ ≐ 687days ≐ 1,88 years.
(only we calculate for Mars instead of the Earth) we get: 
.