Size Comparison

I love seeing the actual sizes of planets and moons in our solar system compared side-by-side to each other. Maybe that's just one of those really nerdy things about myself, nonetheless, it is there.

So, here is a cool image that shows the size comparisons of Mars, Ganymede, Mercury, and The Moon. Now, in case you are wondering (and I know you are), "What is Ganymede?" Ganymede is the largest moon in our solar system and it orbits Jupiter. Everything is bigger at Jupiter. Ganymede is actually bigger than the planet Mercury and almost as big as Mars! And if you also happened to be wondering, the only other moon larger than Mercury is Saturn's moon Titan.


Mars' diameter is 4222 miles
Ganymede's diameter is 3270 miles
Mercury's diameter is 3033 miles
The Moon's diameter is 2160 miles

Now, the official name of The Moon really is The Moon. Weird right? I mean all the other moons in the solar system have names like Ganymede, Callisto, Titan, Ariel, etc. But our moon is just called The Moon. Wow...really? So that leaves us with no other option than to refer to ancient mythologies for names for the Moon. The Romans called it Luna and the Greeks called it Selene.

Since there's so much talk about the Moon, here's an image to the right of the side you never get to see *yawn* Yeah, our side is much more interesting.

Anyway, Selene sounds too girly, unless you're into the whole "mother" earth thing. I prefer to call it Luna (or Lua in Portuguese). Besides, most of the planets are named after Roman gods anyways.

Ceres, the coolest asteroid

Ceres is by far the coolest asteroid in our solar system. It's huge, it's round, and could have tons of water.

How big is it? Well, let's put it this way, if you took the combined mass of all the known asteroids Ceres' mass makes up more than 1/3 of that total.

That's big enough to take on a spherical shape apparently. If you want to know the exact size, it's 578 miles in diameter.

The picture on the left is from Hubble and is the best picture we have of Ceres. However, in 2007 a spacecraft was launched to visit Ceres by 2015. The spacecraft is called Dawn and will pass by Vesta first, which could be the second largest asteroid in the solar system with an irregular diameter that averages around 500 miles.

Ceres is icy like Jupiter's moons Callisto and Europa, but Vesta is all rock.

On the right is a picture comparing Ceres size to Earth.

Mysterious Saturn

Here's a really cool mystery to think about. Where do you find naturally occurring atmospheric hexagons? Why, Saturn of course!

This image is incredible and baffles scientists as they have no idea what could be causing this hurricane-like storm on Saturn's north pole to look like a hexagon.

"This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," said Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere, where circularly-shaped waves and convective cells dominate, is perhaps the last place you'd expect to see such a six-sided geometric figure, yet there it is."

The hexagon is nearly 15,000 miles (25,000 kilometers) across. Nearly four Earths could fit inside it. The thermal imagery shows the hexagon extends about 60 miles (100 kilometers) down into the clouds.

Another interesting mystery our universe continues to surprise us with.