Europe on the Earth, Europa in Outer Space

Ah, Europa. When we look at our own moon and then take a peak at the fourth largest of Jupiter we see a good number of differences.

Well, ladies and gentlemen, those brown gashes across the icy surface are silicate rock; what the moon is primarily composed of. Why are there no craters? Not only is there ice on this baby, there's water, so there aren't any craters left behind, it gets filled in and re-frozen after any collisions. Neato!

She's got a diameter of 3000 km and is the sixth largest moon in the entire solar system (just beneath ours, of course). Galileo found her in January of 1610

That suspected ocean beneath the ice layer is quite fascinating, I must say. With an energy source of tidal heating, no wonder there's thought of the possibility of life being on this special moon. That heat keeps the water liquid and makes a high possibility of geological activity. Imagine? A world of water beneath that surface of ice and rock? Reminds me of something we'd see in Star Trek and it's in our own solar system.

I was surprised to find out that Europa's name wasn't used for a period of time after it's designation and was instead called Jupiter II. How boring. I know I wouldn't like it if I was called Hollett IV just because my parents didn't feel like calling me by my name for a couple of years. Terrible. Too much wine, probably. Thankfully, in the 20th century, they put the bottles back in the cellar and decided to call her (and a few other Galilean satellites) by her proper name. She was called Jupiter II because she was the second satellite to be found orbiting Jupiter. Later on, four more were found and were actually closer to the massive gas giant, and she was then demoted to sixth position. But she's still called Jupiter II. They took away her name but won't change it to make it appropriate again. *Sigh*

As one of the smoothest objects in the solar system, Europa's albedo (light reflectivity) is one of the highest for satellites at 0.64 due to it's icy surface. That's pretty darn bright; no wonder we can see it from Earth on a good clear night.

The Smaller Ice Giant

That is, the eighth planet; beautiful Neptune. In grade six I did a project on this blue gas giant and so I've decided to re-visit it and write a blog for my astronomy class.

This blue beaut is named after the Roman god of the sea. The trident above is that of Poseidon's, which is the planet's symbol. I had no idea planets had symbols, go figure.

Neptune is 17 times the mass of Earth but only 1/18th of Jupiter's mas. It's near-twin, Uranus, being 14. Neptune's density is greater because of the fact that it's volume is less than the other blue gas giant. It's the furthest planet from the sun in our solar system (*cough* stupid definition of a planet *cough*), the fourth largest in diameter, and third largest in mass.

The methane in it's mostly hydrogen and helium atmosphere is what gives it the beautiful blue colour. Its winds gail at up to 2100 km/h, making it the planet with the strongest winds in the solar system, and are generally located in the massive storm in its southern hemisphere; the Great Dark Spot. The temperature at the top of its clouds has been measured at -218 degrees C, one of the coldest in the solar system but that only makes sense because it's the furthest from the sun (*cough* besides poor Pluto *cough*). The core of the planet is, of course, a great deal hotter, at about 7000 degrees C.

It was discovered on September 23, 1846 by three astronomers; Urbain Le Verrier, John Couch Adams, and Johann Galle (but apparently Galileo viewed it in 1612 but he mistook it as a fixed star). Voyager 2 was the only spacecraft to visit it, and flew past the last gas giant on August 25, 1989.

Thirteen satellites circle Neptune, Triton being the largest of them. It's the only one of Neptune's moons large enough to be spherical and was discovered 17 days after the planet itself. There is thought that Triton was once a Kuiper Belt object before it was captured by Neptune's gravitational field. The cool part about the names of Neptune's moons is that since the planet itself is named after the great god of the sea, they are all named after lesser sea gods. I enjoyed that creativity of the astronomers who found them. There was definitely wine involved with the naming of the constellations but not so much with the naming of the planets and their moons.

Though it may not be visible in very many of the pictures (and not in the ones I have placed above), our lovely Neptune has rings! They are (obviously) much less substantial than those of Saturn, but they are azure in colour and are slightly "clumpy". This could be the result of the slight gravitational pulls from the orbiting moons but it's not certain.

There's definitely lots more to be discussed about the pretty blue gas giant (that's clouds aren't boring to look at) but I'll end my blurb for now. Wikipedia is where I got this information and there's plenty left if you're interested to take a look! Good old Neptune, the most respected and feared of gods next to Zeus, and the most beautiful planet next to Earth. Well, someone has to come in second place.