the 13 (for now) Planets of the Solar System

[gareb]

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Of the dwarf planets on the list, Pluto remains the most famous. At only 1,455 miles (2,352 kilometers) across, Pluto is only 20% as big as Earth, and only 0.2% as massive. Did we mention how freaking cold it is? Due to its extremely elliptical orbit, it cruises around the sun at a distance of 3.65 BILLION miles (or 5.87 billion km), taking 248 years to complete one full revolution around the sun. Since Pluto is so distant, we haven't directly observed the dwarf planet, so not much is known about it. However, that will soon change in 2015 when "New Horizons" arrives at Pluto to study the dwarf planet and its four known moons (One of which, Charon, is about half as big as Pluto itself) before heading off to observe asteroids in the Kuiper Belt.

Eris has a name that's quite fitting. Due to the controversy of demoting Pluto, this icy body was named after Eris in greek mythology, whom is the Greek goddess of discord and strife. She stirred up jealous among other goddesses, leading to the Trojan War. As far as size is concerned, Eris is virtually the same size as Pluto, but it's about 25% more massive. This has led scientists to believe Eris contains considerably more rock than its distant neighbor, Pluto. Eris has one known moon, Dysnomia and it takes Eris 557 years to complete one full revolution around the sun.

Haumea is perhaps one of the strangest objects in the solar system, and it's certainly the strangest dwarf planet on this list. Haumea is about 1,200 miles (1,931 km) across, making it almost as wide as Pluto, but it only has 1/3rd of Pluto's mass. That's partly due to it's oblong shape. Unlike the other dwarf planets on this list, Haumea is not spherical. In fact, the dwarf planet's super charged spin (it makes one complete rotation on its axis every four hours) has caused the dwarf planet to be pushed outward at its equator, which forces it to be shaped like a football!

Not much is known about Makemake other than the fact that it orbits the sun from an average distance of 4.26 billion miles (6.85 billion km), slightly farther away than Pluto and that it completes a full orbit around the sun every 310 years.

Last (but certainly not least) is Ceres. Ceres is the only dwarf planet that isn't found in the Kuiper Belt. Rather, it can be found in the asteroid belt that's between Mars and Jupiter. For that reason, it makes a complete orbit around the sun every 4.6 years. Ceres was found long before any of the other protoplanets on this list. In fact, it used to be regarded as a true planet before it was discovered that there are several bodies with significant mass hurtling through space in the asteroid belt. Ceres contains about 1/3rd of the mass in the asteroid belt and astronomers believe Ceres would have continued growing into a full fledged planet the size of Mars had Jupiter not shaken up the asteroid belt long ago.

Meet the Solar System's Dwarf Planets | Pluto, Eris, Ceres & Dwarf Planets | Solar System Exploration & Planet Definition | Space.com

Ceres: Largest Asteroid in Asteroid Belt and Dwarf Planet
Haumea - Icy Dwarf Planet in Kuiper Belt - Discovery and Composition
Makemake - Dwarf Planet in Kuiper Belt - Temperature and Composition
Eris - Dwarf Planet - Tenth Planet - Moon Dysnomia - Discovery

[geo25]

eight ra man. pluto got demoted and is now a dwarf planet like eris and ceres.

[ChaosOrb]

bag.o ra gani nisulti ug 13 planet, 8 jud imo.

BTW, nice find sir gareb, very informative!

[stew_griff]

eight ra man. pluto got demoted and is now a dwarf planet like eris and ceres.

by planet, ts meant dwarf and major planets

[gareb]

4 rocky planets + 4 gas planets + 5 dwarf planets

[GanahanKoNimo]

Informative Now I know ..

[edoy]

13 as of now and still counting, maybe for the next decades

[___iamjana]

very informative.... thanx TS

[jidosha]

neil degrasse tyson says 8 main planets and also the IAU. anything after neptune ky gi consider lng as trans-neptunian objects, with the exemption of five dwarf planets

[rodsky]

Kulang. There are four more, if we push aside the IAU "officiality report" and instead focusing on the CRITERIA.

They are:

1) Orcus 90482 Orcus - Wikipedia, the free encyclopedia

2) Sedna 90377 Sedna - Wikipedia, the free encyclopedia

3) Quaoar 50000 Quaoar - Wikipedia, the free encyclopedia

4) Varuna 20000 Varuna - Wikipedia, the free encyclopedia

I respect the set criteria (agreed by most astronomers and planetary geologists around the world) rather than the IAU "officiality" statement

Furthermore, if criteria is again followed, then at the moment, we actually have more than 1000 dwarf planets or TNU's in the Kuiper Belt. The reason why the IAU decided to declare the 8 planets plus 5 dwarf planets as "official" is more a political decision, so that education departments around the world can declare it to be such so that kids in schools won't be obliged to memorize more than 1000 planets (imagine that)!

-RODION