Montana Skies: Planet Venus

Hey, check it out: The planet Venus has returned to the evening sky, and is visible low in the Southwestern sky, for an hour or two after sunset.

Venus is the brightest thing anywhere in the evening sky, so if you see a bright star-like object in the Southwestern sky at 6 or 7pm:  That's it.  In a decent telescope, Venus looks something like this:

The planet is permanently covered in a thick layer of whitish clouds, so it's impossible to see any surface detail.  This makes a meteorologist's job on Venus really easy:  "We have a 100% chance of overcast skies, from now until FOREVER!"  From far away, Venus looks a lot like the Earth's twin:  It's made of a similar mix of rocks and metals, it has 82% of the Earth's mass, and 95% of the Earth's diameter.  However, the atmosphere of Venus is mostly carbon dioxide and is 93 times thicker than ours, making it hot enough on the surface of Venus to melt lead.  If Venus is our twin, it must be our EVIL twin!  So how did Venus end up with such a different atmosphere?  The answer is that we have oceans:  Liquid water loves to dissolve carbon dioxide.  Then once the carbon dioxide is in the water, a bunch of chemical reactions turn it into limestone and other carbonate rocks.  Our oceans are constantly sucking the carbon dioxide out of our atmosphere, keeping things nice and cool.  Over on Venus, there are no oceans, so the carbon dioxide builds up thicker and thicker, making it a not quite so nice place to take a vacation.  Just in case you were thinking about it! So take a look at the planet Venus, low in the southwest for a couple of hours after sunset, up in our Beautiful Montana Skies!