10 Important Things About the Planet Mercury

My name's Eric Loberg, the director of the Taylor Planetarium at the Museum of the Rockies. I'm going to talk about 10 things that are important with Mercury. The first is that it's closest to the Sun, this seems kind of arbitrary. But a lot of this list wouldn't make sense or they wouldn't be the important things if it wasn't the closest planet to the Sun. Because Mercury is so close, a lot of other things happen. Like the fact that is has no moon. The Sun probably would pull any moon that Mercury might formed with, away from it. Mercury also doesn't have any rings. The same thing would happen if Mercury had rings, the Sun would just pull those rings away from the planet. Mercury doesn't really have an atmosphere, those solar winds blow the atmosphere away from Mercury. In fact those winds are so strong, they pummel the planet and little atoms fly off and it creates an exosphere, which is kind of an atmosphere that surrounds the planet. It's also a very rocky planet, mostly inner planets are rocky. Again, partly due to those solar winds. If there's any gases that formed around Mercury, it just blew them away. All that's left is the rocky remnant. Mercury, because it's the closest planet to the Sun, goes around the Sun as fast as any of the other planets. It has the fastest revolution around the Sun, about 88 days. Mercury does have a very long day, the second longest day of any of the planets. It's day is 58 days and 15 hours long, almost two Earth months long. It's a very long day as it goes around the Sun. Which makes our next point very important as well, the temperatures get down to a 180 degrees below zero Celsius. That go up to 430 degrees above zero Celsius. And so, those temperatures sit on Mercury for a long time. If Mercury takes two months to go around the Sun, that means one-half of that planet is in the baking hot sunlight for almost two months. And then, the other half stays freezing cold for almost two months as well. It has the greatest eccentricity, which is kind of a funny word. That's its orbit shape and so instead of being in a circle, most planets are mostly circular and even Mercury has a mostly circular orbit. But eccentricity means it's stretched out a little, it's a little like an oval. And Mercury has the greatest oval shape of all the planets. Which means it travels faster as it gets close to the Sun, and slower as it gets farther away from the Sun. And it's the smallest planet. And I put this point last, just as kind of an interesting point. If you want to talk about planets as a size, Mercury is in trouble. Mercury is actually smaller than Jupiter's moon, Ganymede, it's also smaller than Saturn's moon, Titan. It's almost as small as the Earth's moon. So it's a very small planet in scale of other things in our solar system. My name's Eric Loberg, this was 10 important things about the planet Mercury.