238Views13Replies

Author Options:

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.

Discussions

0
None
mrmerino

6 years ago

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.

0
None
kelseymh

6 years ago

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

0
None
steveastroukkelseymh

Answer 6 years ago

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

0
None
kelseymhsteveastrouk

Answer 6 years ago

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.

0
None
steveastroukkelseymh

Answer 6 years ago

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

0
None
kelseymhsteveastrouk

Answer 6 years ago

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.

0
None
rickharriskelseymh

Answer 6 years ago

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

0
None
kelseymhrickharris

Answer 6 years ago

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.

0
None
rickharrisJayefuu

Answer 6 years ago

+1
Pluto, Mercury, Saturn, Venus, Earth, Jupiter, Neptune, Mars

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

0
None
Jack A Lopezsteveastrouk

Answer 6 years ago

Yeah. Pluto used to be called a planet,
http://en.wikipedia.org/wiki/Planet#Solar_System
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,
http://en.wikipedia.org/wiki/File:EightTNOs.png

And the rest of the story is here:
http://en.wikipedia.org/wiki/IAU_definition_of_planet
http://en.wikipedia.org/wiki/Trans-Neptunian_object
http://en.wikipedia.org/wiki/Pluto