|Posted on September 3, 2010 at 12:11 PM|
From Sharon Fangonon
I thought someone ought to make a computation of how much closer Mars would have to move away from its current orbit in order to be as large as the Moon.
Let's see if I can figure it out with some back-of- the-envelope computations. The moon is around 27% the size of Earth and it's around 30 times as far as the Earth's diameter. Mars is 53% the size of Earth.
On the average, the Moon is 384,400 km from the Earth. At Mars' closest approach in 2003 (perihelic opposition), it was 55,758,006 km from Earth. At that distance it wasn't even a tiny disc to the naked eye. If it's a simple ratio and proportion, then Mars ought to be 750,553 kms away from Earth to be the size of the Moon.
The average distance of Mars from the sun is 227,700,000 km. Earth's is 149,500,000 km. That's a difference of 78,200,00 km. This means Mars' new orbit should have a radius of around 150,250,000 km. That's only 59 Earth diameters away instead of the normal perihelic distance of 4,370 Earth diameters away.
I don't know what sort of catastrophic event would push Mars closer to the sun. Maybe a huge meteor strike? It would probably be catastrophic for the solar system and Earth, too. Even if Earth doesn't get struck, I wonder what sort of havoc the gravitational pull of a very close planet would mean.