It Might Be a Planet If...
What is a planet? Until recently, there was no exact definition. There were historically six planets. Uranus, Neptune, and Pluto were discovered after the invention of the telescope.
Pluto Until recently, considered the farthest planet from the Sun Smaller than any other planet Too distant to see surface features Photo taken by New Horizons Spacecraft 2015
What About A 10th planet? In 2005, Eris discovered Larger and farther from the Sun than Pluto Publicized at first as the 10th planet More and more objects discovered beyond Pluto
A New Definition Needed If there were many objects about the same size as Pluto located near Pluto s orbit, should they all be considered planets? If Pluto was a planet, why weren t these new objects planets as well?
What has been one source of confusion surrounding planets in our solar system? Because.. has been unclear, this has made somewhat confusing.
So what is a planet? In 2006 the International Astronomical Union came up with three rules for determining whether or not a body is a planet: Must orbit the Sun Must have spherical (ball-like) shape Must clear orbit of other debris
1. Planets orbit their stars. All planets in the Solar System orbit the Sun. If a body in the Solar System orbits around something other than the Sun, it is not a planet.
2. Planets are shaped like a ball (spherical). Planets have enough gravity that they were pulled into a spherical shape when they formed. If the body does not have a generally spherical shape, it is not considered a planet.
3. Planets sweep up their area around the Sun. Planets have enough gravity to clear their orbits of smaller debris. This debris is either captured by the planet and becomes that planet s moon or else it is pushed out of the planet s orbit.
What about Pluto? Pluto is roughly spherically shaped, and it does orbit the Sun. Pluto has not cleared its orbit of other debris. (Kuiper Belt) Scientists have found many other Pluto-like objects near Pluto s orbit. Pluto was given a new classification as a dwarf planet.
What characteristics define a planet? To be a planet, it must.
Introducing the Dwarf Planets Dwarf planets only fulfill two of the three requirements to be a planet: They orbit the Sun. They are roughly spherically shaped. They have NOT cleared their area of all other debris.
Our Eight-Planet Solar System Scientists now say that our Solar System has only eight planets. Pluto is no longer considered a planet. Our Solar System now has FIVE dwarf planets: Pluto, Eris, and Ceres, Haumea, and Makemake. Pluto, Eris, Haumea, and Makemake are located beyond Neptune- in the Kuiper Belt. Ceres is the largest body in the asteroid belt between Mars and Jupiter.
Other Members of the Solar Family Besides planets and dwarf planets, there are many other objects in the Solar System. Some of the major non-planet objects include moons, asteroids, and comets.
Moons Bodies that orbit other things in the Solar System besides the Sun. Many of the planets have moons. Earth has one moon. Mars has two. Jupiter has over SIXTY. Even some smaller objects like dwarf planets and asteroids have moons.
Asteroids Large pieces of rocky debris that orbit the Sun. Many are found in the Asteroid Belt between Mars and Jupiter. Thought to be debris from a planet that never formed.
Comets- Oort Cloud Large pieces of rock and ice that orbit the Sun beyond Neptune. Occasionally are bumped out of orbit and fall in toward the Sun. As they approach the Sun, ice and dust is burned off to form a tail stretching away from the Sun.
Our Solar System: THE SUN!!!!!! Eight planets Five dwarf planets Moons Asteroids
Is there a possible 9 th planet?
Does it... Orbit its star? Have a spherical shape? Have enough mass (and thus, gravity) to clear its surroundings of smaller debris? Mars Pluto Europa (one of Jupiter s moons) Comets Asteroids