STEREO Orbits

 

Challenge Part 2

 

In part 1 of the challenge we were assuming that the orbit of the Earth and both spacecraft is circular around the Sun.

 

In reality the orbits are elliptical.

 

Circular                                     Elliptical

             

 

The words ‘Perihelion’ and ‘Aphelion’ are used to describe the shape of an ellipse.

Perihelion is the smallest distance between the centre of orbit and a point on the orbit.

Aphelion is the greatest distance between the centre of orbit and a point on the orbit.

 

 

Try drawing a diagram with the Earth’s orbit virtually circular around the Sun.

Now draw in an ellipse where the distance between the Earth and the Sun is its Perihelion, which spacecraft could this be?

(Hint – is the orbit inside or outside that of the Earth?, look back at your answer to Part 1)

Now draw in an ellipse where the distance between the Earth and the Sun is its Aphelion, which spacecraft could this be?