Tuesday, October 20, 2015

Earth and natural satellites

Today's planet is Earth.  Earth is the third planet from the sun, and at just the right distance to stay warm enough to have liquid water, but not so close to the sun to not have liquid water.  In other words, it has liquid water, which seems to be very important for life, which is why Mars is looking so interesting recently.  But I digress. 
The human, boat, plane and house would be fine on most of the Earth, since they were built for Earth.  But, let's say you wanted to make the Earth uninhabitable.  Or, better yet, non-existent.  Luckily for you, someone has made a list of plausible ways to destroy the Earth. 

On to the Moon!  The Moon is unusual among solar system moons in its relative size to it's primary.  The most widely accepted explanation for the Moon's unusual size is that, approximately 4.5 billion years ago, a Mars-sized planet called Theia collided with Earth in a clanking blow, creating a field of debris from both Theia and Earth in orbit of Earth, which later coalesced into the Moon. 
The color of the Moon is surprisingly deceptive, it looks like a light grey, but it's actually an asphalt color:

The gravity on the Moon is about one sixth of Earth's gravity.  The plane wouldn't be able to fly, because of the lack of atmosphere.  The boat wouldn't be very interesting, because the lunar "seas" or "mares" are made out of hardened basalt flows.
The human would need a spacesuit, because of the lack of oxygen, and the temperature, ranging from 242 degrees F (100 K) during the day to -280 degrees F (100 K) during the night.  We know this is possible, because of the Apollo Moon landing program.  The house shouldn't have too much trouble, but probably cycles of hot and cold and solar radiation would eventually wear it down.
The Moon is habitable enough that food and water could be a problem.  Food would have to be brought with you, or farmed in a pressurized greenhouse.  Water is a problem, because at the equator, water wouldn't last very long, not near the surface, anyway.  However, at the lunar south pole, there are craters where sunlight never reaches the bottom.  This is a likely location for water ice, because that strong evidence for water ice has been found there.  Also, because sunlight never hits the bottom of the craters, a lunar base would have to deal with less temperature extremes. 

That's it for the Earth and Moon, see you on Mars!