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what are the planets on the solar system? Answered

well the earth is the third planet from the sun. Pluto is also a planet but it is the smallest planet and coldest one to. Earth is between Mars and Venus.


For a really long time, astronomers thought there was a small planet between Mercury and the Sun, due to the discrepancies in Mercury's orbit and its predictions. It turned out that the problems were caused by general relativity- the mass of the Sun was distorting time and mucking up Mercury's orbit.

They called this planet Vulcan.

Pluto is a "dwarf planet" not a planet. I will leave it to you to complete your homework by finding out why.

Because the IAU SAID so, and it made a lot of astronomers cross too.

Yes, they said so. And they provided a rational (if arbitrary) definition, which had never existed before. Prior to the 2006 IAU decision, the term "planet" was not well-defined at all, and was assigned, removed, and reassigned essentially at the whim of the astronomical community. Look up the history of early asteroid discoveries, for example.

What actually seems to have put the final nail in the coffin is the discovery of a bigger dwarf planet than Pluto, Eris,

Yes, indeed. That's the same thing that happened with the asteroids: originally, Ceres, Vesta, Pallas, and a couple of others were all being called "planets," with their own astronomical symbols and everything. Once about a dozen or so had been discovered, with an obviously large population still out there, astronomers basically said, "screw this," and came up with a different naming convention.

My definition - can I stand on it - will it: sake more than an hour to circumnavigate - if so its a planet (small) :-)

But that definition is incomplete -- circumnavigate at what speed? Low orbit? High orbit? Surface travel? With a human driver or with a robot rover? It also doesn't address any of the astronomical observational issues related to identifying a planet.

Pluto, Mercury, Saturn, Venus, Earth, Jupiter, Neptune, Mars

However they are not in the right order - That's for you to research.

Yeah. Pluto used to be called a planet,
but it got demoted after the discovery of half a dozen or so other rocks, now called trans-Neptunian objects (TNOs), that are similar in size, and orbit, to Pluto.  At the time of this writing, the Solar system is known to have about as many Pluto-sized TNOs as it does true planets. 

I found a nice graphic, here,

And the rest of the story is here: