Planet George
Published on Nov 15, 2005 at 8:03 pm.
2 Comments.
Filed under astronomers, planets.
I just gave a little public seminar on planets, and in particular the “new” tenth planet announced back a couple months ago. I’ll say more about that in a later blog, though, if y’all are interested.
In order to talk about planets, you need to know what you are talking about. So, what is a planet? The term comes from the Greek for a wanderer. The ancients would look up and notice that the stars were always in the same place relative to one another, and so you could imagine shapes and figures in the sky, and these shapes and figures would remain constant. That was true except for five “stars” that moved from constellation to constellation at varying speeds. These were Mercury, Venus, Mars, Jupiter, and Saturn. Oh, and the Moon also moved between the constellations. And, if you dimmed the Sun enough to see the stars behind it, then it, too, seems to move between the constellations. So, that makes seven “planets.” Hey, there are seven days of the week, too. The Sun’s day, the Moon’s day, and even Saturn’s day. The others are named after more Teutonic gods, but in Latin, French, or Spanish, they are clearly named for the planets.
Astronomers eventually realized that the Sun is not a planet, and in fact the planets orbit the Sun. The Moon orbits Earth, so they figured that it shouldn’t be a planet. That made the planets Mercury, Venus, Earth, Mars, Jupiter, and Saturn. Additionally, moons were found around Jupiter and Saturn. Eventually, in 1781 William Herschel and his sister Caroline Herschel discover a small disk in the sky using his telescope. Well, after observing for a bit, he realizes that the disk moved. But, the only things that moved were comets and planets. It wasn’t a comet. So, he realized eventually that it was a planet. He decided to name it George (actually, Sidus Georgium) after King George III, in whose name he had gotten a grant to build a telescope. So, the Solar System was Mercury, Venus, Earth, Mars, Jupiter, Saturn, and George. The name didn’t stick, so the planet was renamed Uranus. However, King George III made William Herschel and his sister Caroline royal astronomers to the king.
Not long afterwards, astronomers began to find tiny objects between Mars and Jupiter. At first they were thought to be planets, but no matter the magnification, they were never more than dots in the telescope. That meant that they had to be very small — too small to be planets they figured. So, the term asteroid was coined to describe them. They are small rocky things. Some are the size of houses, others are hundreds of miles across, with every size in between. At one time, there was speculation that the asteroids might be a planet that somehow was destroyed, but we now believe them to be relics of the formation of the Solar System. They never did get together to form a planet.
After watching the orbit of Uranus for long enough, astronomers also realized that there must be another planet beyond it that is interacting with it gravitationally. A search for the object netted Neptune. That is a really fascinating story, too, about how Neptune was discovered.
Pluto is weird, so we won’t deal with it just now. It is way too small to make the list of planets if it were discovered today. It made the list by accident. The new object is slightly larger than Pluto, so that is why the media called it a planet. But, there are objects of the same composition that are just a tiny bit smaller than Pluto, and some a tiny smaller than they, and so on. Where do you make the cutoff?
Unfortunately, it turns out that astronomers never got around to making a definition of a planet. It just seemed so obvious. Hmm. Oh, well. It is really just a label, anyway. So, if you ask me, there are multiple categories of objects, and it isn’t fair to lump them all together under one umbrella term “planet.” After all, Jupiter and Earth have very little in common other than that they orbit the Sun. Earth and Venus have a lot in common, and Jupiter and Saturn have a lot in common with one another. So, maybe we need to refine our definitions.
-Astroprof
Astroprof’s Page » Planetary Symbols on September 28, 2007 at 11:43 pm: 1
[…] There are two commonly used symbols for the planet Uranus. The first of these resembles a cross between the symbols of the Sun and of Mars. It is sometimes referred to as a very stylized shield and spear. Uranus is a Latinized form of the Ouranus, which was the Greek god of the sky and father of Saturn and many of the other gods. Interestingly, this symbol was also sometimes used by alchemists to represent the element platinum. This is the symbol that I have most often seen for the planet Uranus. However, there is another one that is sometimes seen. This second symbol has the form of a stylized H, reportedly honoring William Herschell, who discovered the planet Uranus. At the time of his discovery, he originally wanted to name the planet “George,” but that name wasn’t accepted by the astronomical community as a whole. Johann Bode suggested that Herschell name the planet “Neptune” because of its bluish-green color. However, Herschell didn’t go along with that. If he couldn’t name the planet George, he wasn’t going to name it Neptune. So, he eventually settled on the name Uranus. That makes sense, since in mythology Uranus was the father of Saturn who was the father of Jupiter. That put successively the outer planets as representing older and slower gods the farther they were from the Sun (and the slower that they moved). […]
Mirhan on February 15, 2011 at 4:31 am: 2
Wednesday also sounds like “Venus’s day”