Wednesday, August 29, 2012

A Quick Enceladus Note, And Other Stuff

Triton is the largest moon of the planet Neptune, discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. At 2,700 km in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to Pluto's, Triton is thought to have been captured from the Kuiper belt. Triton has a surface of mostly frozen nitrogen, a mostly water ice crust, an icy mantle and a substantial core of rock and metal.

... Triton is geologically active; its surface is young and has relatively few impact craters. Although Triton is made of various ices, its subsurface processes are similar to those that produce volcanoes and rift valleys on Earth, but with water and ammonia lavas as opposed to liquid rock. Triton's entire surface is cut by complex valleys and ridges, probably the result of tectonics and icy volcanism. The vast majority of surface features on Triton are endogenic—the result of internal geological processes rather than external processes such as impacts. Most are volcanic and extrusive in nature, rather than tectonic.

The Voyager 2 probe observed a handful of geyser-like eruptions of invisible nitrogen gas and entrained dust from beneath the surface of Triton in plumes up to 8 km high. Triton thus joins the Earth, Io, and Enceladus as one of the few worlds of the Solar System on which active eruptions of some sort have been observed. (Venus, Mars, Europa, Titan, and Dione may also be volcanically active.)

Triton at Wikipedia

Today I was reading about Triton, the moon of Neptune, at Wikipedia (wasn’t everyone?) and when I got to that part about Triton being one of the few places in the solar system along with only the Earth, Io and Enceladus where volcanism has been observed, I felt kind of proud—I mean that here at the blog I’ve done a post about Enceladus, Enceladus Was A Child Of Gaia.

And that reminded me that I had posted about “Gaia” in two different contexts, first as the name of the cool Roland synthesizer in Little Complicated Things And Stuff, and then as one of the Titans in The Occult Technology Of Guitars And Keyboards.

All that got me thinking that I haven’t said much about the moons of Jupiter, and I don’t think I’ve posted anything about the moon Io at all. I’m not sure why I’ve never posted about Io, because there are some interesting things there:

Io is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres (2,263 mi), the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus.

With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of the moon's silicate crust. Some of these peaks are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System, which are mostly composed of water-ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost.

Io at Wikipedia

I’ve posted about volcanism here on Earth, even in off-hand ways, like in When The Planet Convulses And Glowing Lava Flows. But I haven’t said much about volcanism in the solar system.

In fact, this has sort of underscored for me that I seem to be more interested in exotic snows than in volcanism in outer space.

Pluto In Magic And Alchemy

Dragon Storm: Ammonia Snow

Exotic Snows And An Ink Drawing Of Plants

And in addition to Enceladus I’ve certainly posted about the moons in the outer system. Just recently I posted about Pluto’s moons, and I enjoyed writing about Miranda, both the woman and the moon of Uranus:

Pluto’s Fifth Moon Has No Name (Yet)

Prospero I Know At The End

Miranda And Miranda And Miranda

The Moon Miranda (A Note)

So, anyway, there is a reason I was reading about Triton today but I’m not going to get to that now. Now I just wanted to review this business about the outer moons, and to note that I am more interested in exotic snows in outer space than volcanism in outer space.

Whatever that might say about me.

Finally on this topic of the outer solar system in general I’m going to end with one other link.

I’ve been fortunate to actually observe Neptune and Uranus in real life—although only through small refractor telescopes, a 2.4 inch and a 4 inch. Someday I hope to get back out there, so to speak, and observe them with a larger telescope.

And one of my favorite posts about this topic is: A Bird Who Could Fly To Neptune

Someday I still hope to meet that bird, too.

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