Other Solar System Objects
There are 8 planets that orbit the Sun. But there are many other things that orbit the Sun as well. We'll take a look at these other objects here: dwarf planets, asteroids, Kuiper Belt Objects, comets, and meteoroids/meteors/meteorites.
Dwarf Planets
If you were to travel back in time to the distant past, 2000, and talked about dwarf planets, people would look at you funny. But now, we accept them (for the most part) as part of our Solar System. The story of dwarf planets starts back in 2003 when the first object of significant size was found beyond Neptune in the neighborhood of Pluto. It was even given a name, Quaoar. The Kuiper Belt had big things in it and one may be bigger than Pluto. Well, it happened in 2005. An object slightly bigger than Pluto was discovered way beyond Pluto. It was hailed as being the "10th planet." It was given a name, Eris (the goddess of strife and discord). But the discoverer had apprehensions. He didn't think it was a planet as much as a larger version of the other things found in the Kuiper Belt. And Pluto was more like it than the other planets. So, maybe Pluto wasn't a planet either. The IAU (International Astronomical Union) voted on the definition of a planet and decided that Eris did not fit that definition...nor did Pluto. They established a new category, dwarf planet. Amazingly, people are still upset that Pluto is not a planet (I really have no idea why. It doesn't affect their lives at all.). Keep in mind that at one point in history the Sun, Moon, and some of the asteroids were all considered planets and that Earth wasn't. So, yeah, the definition changes. Big deal. There are several recognized dwarf planets: Pluto, Eris, Ceres, Quaoar, Orcus, Haumea, Makemake (great story for this one; but, alas, not necessary for the SOL), and Sedna (maybe a dwarf planet, maybe not...it's really far away).
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Pluto
No, Pluto is not a planet. It's a dwarf planet. And we're going to finally see what it really looks like in July 2015 when New Horizons gets there. Discovered in 1930, Pluto became an instant sensation. Maybe it was because an American, Clyde Tombaugh, who discovered it or maybe it was because Disney named a dog after it; either way, it was popular. But it made an odd planet. Strike 1: It is tiny. It's smaller than the Moon. It's smaller than the United States. It would fit between the Appalachians and the Rockies. But it lives in the realm of the gas giants. Strike 2: It's a rock in a neighborhood of gas balls. Strike 3: It has 5 moons (Charon, Styx, Hydra, Nix, and Kerberos) whereas the other planets nearby have more than a dozen...each. Strike 4 (I know, 3 strikes and you're out, but Pluto has a lot wrong with it to be a planet): Its orbit is weird. For part of its orbit, it crosses the orbit of Neptune and is between Neptune and Uranus. No other planet does that. Strike 5: Its orbit is eccentric. While almost all other planets are on a fairly even plane of orbit with each other, Pluto's orbit is tilted and goes above and below the orbits of the other planets. Strike 6: It might be a double planet system. Charon is so big compared to Pluto that it orbits a point outside of Pluto, meaning that they orbit each other to a degree. Again, no other planet does this. Finally, Strike 7: Eris was thought to be bigger (by a little, but still bigger...we now know that Pluto is slightly larger, at least until we manage to visit Eris). Any wonder why Pluto's not a planet anymore? It never should have been a planet, but just because it was does not make it a planet forever (take a look at Ceres, below).
No, Pluto is not a planet. It's a dwarf planet. And we're going to finally see what it really looks like in July 2015 when New Horizons gets there. Discovered in 1930, Pluto became an instant sensation. Maybe it was because an American, Clyde Tombaugh, who discovered it or maybe it was because Disney named a dog after it; either way, it was popular. But it made an odd planet. Strike 1: It is tiny. It's smaller than the Moon. It's smaller than the United States. It would fit between the Appalachians and the Rockies. But it lives in the realm of the gas giants. Strike 2: It's a rock in a neighborhood of gas balls. Strike 3: It has 5 moons (Charon, Styx, Hydra, Nix, and Kerberos) whereas the other planets nearby have more than a dozen...each. Strike 4 (I know, 3 strikes and you're out, but Pluto has a lot wrong with it to be a planet): Its orbit is weird. For part of its orbit, it crosses the orbit of Neptune and is between Neptune and Uranus. No other planet does that. Strike 5: Its orbit is eccentric. While almost all other planets are on a fairly even plane of orbit with each other, Pluto's orbit is tilted and goes above and below the orbits of the other planets. Strike 6: It might be a double planet system. Charon is so big compared to Pluto that it orbits a point outside of Pluto, meaning that they orbit each other to a degree. Again, no other planet does this. Finally, Strike 7: Eris was thought to be bigger (by a little, but still bigger...we now know that Pluto is slightly larger, at least until we manage to visit Eris). Any wonder why Pluto's not a planet anymore? It never should have been a planet, but just because it was does not make it a planet forever (take a look at Ceres, below).
Eris
Eris was discovered in 2005 and was originally nicknamed Xena (a play on the idea of a "planet X" and a reference to the warrior princess on TV). It exists in the Kuiper Belt and has only 1 moon, Dysnomia. It seems to be slightly larger than Pluto. It was discovered by Mike Brown and his team.
Eris was discovered in 2005 and was originally nicknamed Xena (a play on the idea of a "planet X" and a reference to the warrior princess on TV). It exists in the Kuiper Belt and has only 1 moon, Dysnomia. It seems to be slightly larger than Pluto. It was discovered by Mike Brown and his team.
Ceres
Ceres resides in the Asteroid Belt. It was discovered after Uranus at the beginning of the 19th century. Originally, it was considered a planet (technically, it is: planet means "wanderer"). But the discoverer of Uranus, Sir William Herschel, was not pleased by sharing the spotlight of planet discovery. He was the Astronomer Royal for England and pointed out that Ceres existed between Mars and Jupiter. That must mean it's small if we could see those two planets but not Ceres until now. So, he proposed an ultimately silly name, asteroid which means "star-like." Asteroids are definitely not star-like, but they're not planets either. So, Ceres languished as an asteroid until 2006 when the designation of dwarf planet was created. So, if any object has reason to object because of reclassification, it's Ceres.
Ceres resides in the Asteroid Belt. It was discovered after Uranus at the beginning of the 19th century. Originally, it was considered a planet (technically, it is: planet means "wanderer"). But the discoverer of Uranus, Sir William Herschel, was not pleased by sharing the spotlight of planet discovery. He was the Astronomer Royal for England and pointed out that Ceres existed between Mars and Jupiter. That must mean it's small if we could see those two planets but not Ceres until now. So, he proposed an ultimately silly name, asteroid which means "star-like." Asteroids are definitely not star-like, but they're not planets either. So, Ceres languished as an asteroid until 2006 when the designation of dwarf planet was created. So, if any object has reason to object because of reclassification, it's Ceres.
Asteroid Belt
Between Mars and Jupiter, there exists a large number of rocks ranging in size from pebbles and dust to the dwarf planet, Ceres, orbiting the Sun. The Asteroid Belt is typically depicted as being a congested area of rocks of varying sizes. In actuality, we could travel through the Asteroid Belt without seeing a single asteroid. The average distance between asteroids is millions of miles. There's a lot of room in space. Asteroids are not restricted to the area between Mars and Jupiter. Many asteroids move within the inner Solar System often crossing paths with Earth's orbit. Any one of these could potentially hit us. The more we find, the more cluttered we find that the inner Solar System is.
Between Mars and Jupiter, there exists a large number of rocks ranging in size from pebbles and dust to the dwarf planet, Ceres, orbiting the Sun. The Asteroid Belt is typically depicted as being a congested area of rocks of varying sizes. In actuality, we could travel through the Asteroid Belt without seeing a single asteroid. The average distance between asteroids is millions of miles. There's a lot of room in space. Asteroids are not restricted to the area between Mars and Jupiter. Many asteroids move within the inner Solar System often crossing paths with Earth's orbit. Any one of these could potentially hit us. The more we find, the more cluttered we find that the inner Solar System is.
Kuiper Belt
In the 1950s, a scientist proposed the existence of rocky objects beyond the orbit of Neptune. In 1992, we discovered the first Kuiper Belt Object. Similar to the Asteroid Belt, the Kuiper Belt is made of rocks and ice orbiting the Sun in the outer part of the Solar System. Most of the dwarf planets are found out here. It's unknown just how big the Kuiper Belt is, but if Sedna is in it, then it's very big.
In the 1950s, a scientist proposed the existence of rocky objects beyond the orbit of Neptune. In 1992, we discovered the first Kuiper Belt Object. Similar to the Asteroid Belt, the Kuiper Belt is made of rocks and ice orbiting the Sun in the outer part of the Solar System. Most of the dwarf planets are found out here. It's unknown just how big the Kuiper Belt is, but if Sedna is in it, then it's very big.
Comets
Dirty snowballs. That's how comets are typically described. Made of rock and ice, comets appear to slowly streak (oxymoron) across the sky. Long considered to be harbingers or messengers of doom and destruction, comets have no bearing on our personal lives. The most distinct feature of a comet is its tail. When the Sun's light comes into contact with the comet, the ice vaporizes and causes bits of rock and gas to form a tail. The tail always points away from the Sun. The Sun is what creates the tail, so no matter which direction the comet is moving, the tail will point away from the Sun.
Dirty snowballs. That's how comets are typically described. Made of rock and ice, comets appear to slowly streak (oxymoron) across the sky. Long considered to be harbingers or messengers of doom and destruction, comets have no bearing on our personal lives. The most distinct feature of a comet is its tail. When the Sun's light comes into contact with the comet, the ice vaporizes and causes bits of rock and gas to form a tail. The tail always points away from the Sun. The Sun is what creates the tail, so no matter which direction the comet is moving, the tail will point away from the Sun.
Meteoroids/Meteors/Meteorites
Location, location, location! That is the defining characteristic that distinguishes meteoroid from meteor and from meteorite. While there are different types of meteorites, a specific type of meteoroid will become that same type of meteor and, possibly, that same type of meteorite.
Meteoroid - A rock in space
Meteor - A rock that has entered our atmosphere (shooting or falling stars)
Meteorite - A meteor that makes contact with the surface of the Earth
Location, location, location! That is the defining characteristic that distinguishes meteoroid from meteor and from meteorite. While there are different types of meteorites, a specific type of meteoroid will become that same type of meteor and, possibly, that same type of meteorite.
Meteoroid - A rock in space
Meteor - A rock that has entered our atmosphere (shooting or falling stars)
Meteorite - A meteor that makes contact with the surface of the Earth