PV Gap

Carolyn Said:

Which Planet is now recently listed out from our Solar System?

We Answered:

I know you're probably thinking of Pluto,
which used to be called a planet but is now properly regarded
(along with Charon, and other far-away objects that do not sweep their orbits) as a "dwarf planet (which is a polite name for large asteroid).

However, there have been a number of celestial objects once classified as planets but since demoted. Long before Pluto (and Neptune) were discovered, some of the larger chunks in the asteroid belt were actually designated as "planets". These included Ceres, which is over 400 miles long (but far from round). Later, these were reclassified, since they don't sweep clear their orbit, etc.

Pluto should never have been called a "planet".
The famous astronomer, Percival Lowell, spent his last years searching for Planet X and never found it. (His calculations were wrongly based on incorrect mass values for Uranus and Neptune.) When Clyde Tombaugh found something out beyond Neptune, there was much pressure to name it after Lowell; "Pluto" was a compromise, since it began with the initials P and L, but it really wasn't a planet to begin with!

Now that we've found over a hundred real planets orbiting other stars, it's good that we've finally gotten our definitions straight!

The word "planet" means wanderer. The five visible planets do not rotate with the other stars and constellations, but wander across them. Uranus and Neptune (along with Ceres, Pluto, Vesta, Quauar, etc.) are not visible to the naked eye from Earth, so the name is a bit of a stretch in the first place.

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Jaime Said:

List Formation of Solar System (First to Last)?

We Answered:

formation of solar nebula
rotation of nebula
onset of collapse of nebula
accretion of sun
T-tauri event
onset of fusion inside sun
generation of solar wind
formation of protoplanetary disk
accretion of planets
stabilization of planetary orbits

Terrence Said:

List the features of our solar system that any theory of solar system formation must be able to explain.?

We Answered:

The orbits of the planets (angular momentum).
The elemental abundances for the planets.

Clara Said:

Using the new planets in our solar system, write an acrostic?

We Answered:

My Very Excellent Mother Carried Joe Smith Under Nets Positioned Chaotically in 2003

...Well it works lol

Carol Said:

Can anyone tell me the most recent list of planets in our solar system?

We Answered:

Official planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Official dwarf planets: Ceres, Pluto, Haumea, Makemake, Eris.

There are a number of other bodies in our solar system that might meet the requirements for dwarf planet status (many of which are in the Kuiper belt), but they've yet to be "officially" classified as such.

As far as I know, there are no other objects in our solar system that would qualify as planets, or at least any that have been discovered. There are always rumours about other trans-Plutoid planets being out there somewhere, but none have been confirmed.

Crystal Said:

Is This A Proper Definition Of A Planet and A Complete List Of Known Planets In Our Solar System?

We Answered:

This was the proposed definition and list of planets going into the IAU meeting in Prague two years ago. The eventual vote added a thrid criterion about having gravitational dominance (the phrase used was "cleared the neighbourhood of its orbit") with the result that only 8 bodies met the definition of planet (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.) Ceres, Pluto and Eris are considered "dwarf planets" (they meet your 2 criteria but not the third.) Pluto and Eris (and Makemake) are considered to be in a special category of dwarf planets called "plutoid." Charon is still classified as a natural satellite or moon.

Now some people, including some astronomers would agree that your definition does indeed make sense. I think they would probably still exclude Charon as a moon but they might add a few other names of bodies that in all likelihood are spherical due to the influence of gravity.