Posted on March 25, 2018
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| Galileo famously got in trouble with officials of the Catholic church for his idea that the Earth was NOT the immovable center of the universe. |
You may know that it took centuries - millennia! - of humans watching the sky before anyone saw a moon circling any planet other than Earth. When Galileo discovered four of Jupiter's moons, starting in 1610 and using his early telescopes, it shook the world and the worldview - we might actually say the "cosmic view" - of scientists, church officials, and the general public.
Of course, it being the early 1600s, it was a
looooooooonnnnnnnggggggg,
sllllllllloooooooooooooowwwwwww
shake up - because news didn't travel fast, and it took a long time before many people accepted or even knew about Galileo's observations.
But even though it was a slo-mo revolution, the sighting of four moons circling Jupiter was revolutionary because, for the first time, the observation of moons circling another planet established:
- Some things in the cosmos cannot be seen at all by the naked eye. The telescope can reveal things we had not even imagined existing before. (This seems obvious now, but until it happened, it wasn't!)
- Some things in the cosmos didn't orbit Earth. Before the Jovian moons, it seemed to humans that the Sun, Moon, planets, and even the stars circled around *US* - Earth, the center of the cosmos. Seeing moons circling Jupiter gave a big push toward unseating the Earth-centered-universe idea.
Flash forward almost half a century, and we come to the Dutch astronomer Christiaan Huygens. He and his brother, inspired by Galileo's discovery of moons around Jupiter, started building telescopes in 1650. They looked for a possible moon orbiting Saturn - and on this date in 1655, Christiaan found it!Usually, whoever discovers a new land or moon or whatever gets to name it...but Huygens (perhaps imagining that Saturn, like Earth, had only one moon) only gave it the name Saturni Luna, Saturn's moon. As you can imagine, that name had to give way once Giovanni Cassini discovered four more mons of Saturn (between 1673 and 1686). Cassini started naming the moons Saturn I, Saturn II, etc., with the smaller numbers (expressed in Roman numerals) being the moons that are closest to the planet. So at one point, Titan became Saturn II, and later it got changed to Saturn IV. (Translation: Saturn 2 and Saturn 4.)
That just got confusing, though, because, as scientists discovered more and more of Saturn's moons (there are 63 known, confirmed moons that we know of, so far), SOME of those moons were smaller moons that were closer to Saturn - so the "names" of the moons had to keep changing.
Like I said: confusing.
In 1789, the numbering scheme was frozen with the moons known then; Titan was Saturn VI. (Translation: Saturn 6.)
And in 1847, John Herschel suggested the names for the then-known moons of Saturn. There were seven known moons then, and since Saturn was the Roman god of agriculture (named Cronus in Greek mythology), Herschel proposed that the moons be named for brothers and sisters of Cronus, who were as a group of giants called Titans. And, since Titan is not only the first one discovered, but also the largest of Saturn's moons...it got the name Titan, which is also an English word meaning giant. (The word titanic means gigantic, or really-really-really large. Of course, a really large ship named Titanic once crashed into an iceberg and sank!)
Here are some things we humans have discovered about Titan since its first discovery:
It's larger than the smallest planet, which is Mercury. (Remember, Pluto isn't a planet, but rather a dwarf planet. Titan is larger than Pluto and all of the other dwarf planets, too.)
We actually landed a probe on the surface of Titan. This is a first for humans: the first landing of a probe on a moon in the outer solar system. (The probe is named Huygens, by the way.)
Here is a photo from the probe:
Titan has lakes!
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| This is an actual photo of a large lake on Titan. |
Granted, they're not water lakes; instead, liquid methane flows more slowly than water, like lava, forming streams, rivers, lakes, and seas.
As a matter of fact, just like Earth has a "water cycle," Titan has a hydrocarbon cycle. There are upwellings of methane that fall back to the surface in a sort of methane rainstorm!
Titan may be our best chance for discovery of alien life in the solar system. Because some of the hydrocarbon lakes have partially evaporated, the planet has a kind of smog that hides the surface.
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| NOT a large, humanoid alien like this! |
One of the most interesting things to contemplate is the possible beauty of the skies of he moons of Saturn, because Saturn has such a large system of rings. Space artists often paint pictures of possible landscapes of Titan:
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| Again, remember, the picture above and the two pictures below are just paintings by artists who are making guesses about what Titan looks like, based on what scientists knew at the time they create their art. |
Also on this date:
Independence Day in Greece
Anniversary of the Arengo in San Marino
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