[Red Badger]

It’s in a rather large elliptical orbit as per the diagram.

The Sun is just one focus. Where is the other?..........

[alexander_busek]

The Sun is just one focus. Where is the other?..........

The ellipse is always symmetrical. The other focus would be at the opposite side of the ellipse, at the same distance to the ellipse itself. Just draw a straight line through the entire ellipse, intersecting the perihelion and the Sun.

In the above image, the foci are at F and F'.

In the case of a perfectly circular orbit, the two foci collapse to a single point.

Regards,