Comments on: Ynet – A Falling Star Down Under Punditry in the Middle East Thu, 03 Sep 2015 00:11:07 +0000 hourly 1 By: JF Thu, 21 Feb 2013 17:44:43 +0000 Actually, the Moon and the Earth form a double planet system, where you could call either one of them the “planet”.

If you have a proper planet-moon system, the moon “falls away” from the sun during part of its orbit – the moon’s orbit is, part of the time, convex toward the sun. A moon’s orbit is always concave toward the planet it orbits and the planet’s orbit is always concave towards the sun it orbits.

However, for the Earth-Moon system, both orbits are always concave towards the Sun. If you were to plot either orbit on its own, the orbit would form a circle with wobbly edges – it just doesn’t look that way in conventional pictures.

However, people are happier calling the Moon “a moon”, so who am I to argue?