What does a planet have to be to be a planet?

Answer 1

In our solar system, a planet needs to revolve directly around the Sun.

Also, it has to be (more or less) spherical due to its own gravity.

Finally it has to have cleared its orbital neighborhood so that it is the dominant body.

Answer 2

All that stuff the guy/girl wrote before didnt answer the question so i think I'll write a better one! Here goes....

for scientists its mainly these 10 things:

1) Mass

2) Radius / Diameter

3) Shape, spherical, spheroid, others

4) Location, around a star, substar, free floating

5) Orbits, only a star, substar, no star, another planetary object

6) Able to clear its orbit of other objects

7) Origins, from a disk or collapse globule. Maybe it formed to a Brown Dwarf but a nearby bright star reduced its mass

8) A solid surface, or least a liquid surface

9) Able to maintain an atmosphere

10) Does not create a cometary tail

Answer 3

According to the International Astronomical Union, the body authorized to decide such things, a planet must meet these three criteria:

1. It must orbit the Sun, not another planet.
2. It must be massive enough to achieve "hydrostatic equilibrium" - meaning, its gravity has crushed it into a spherical shape
3. It has cleared the neighborhood of its orbit.

Curiously, there never was any definition of "planet" until several teams of astronomers discovered a number of planet-like objects in the distant solar system; each had a claim to be the "Tenth Planet!!". In 2006, the IAU met to consider these claims and defined "planet" in a way that NONE of them would qualify - but which also disqualified Pluto.

The IAU also created the category of "dwarf planet" for any object which met the first two criteria but not the third. So Pluto, formerly the 9th planet, became a "dwarf planet", and Ceres, previously the largest asteroid, joined it. Three other planetary candidates were declared to be "dwarf planets" - Eris (whose provisional name was to be "Xena"), Haumea and Makemake.

It is absolutely certain that there are many other - probably HUNDREDS - of other "dwarf planets" in the Kuiper Belt.

Answer 4

To qualify as a planet, a body has to be approximately spherical (achieving hydrostatic equilibrium under its own gravity), it has to orbit the sun and it has to have cleared its orbit of all other objects - so that at that distance from the sun, there are no other sizable bodies. Some dwarf planets, like pluto, fulfill the first two requirements, but not the last one, this is why they are deemed dwarf planets rather than planets.

Answer 5

To be able to be inhabited?

well oxygen..water..plant life which goes with oxygen really

Answer 6

The first: The object must be in orbit around a star or the remnant of a star.

Answer 7

It has to be able to clear smaller objects in it's orbit, it has to be at least a moderate size, and it does NOT orbit any other planet, with the exception of duel star systems.

Answer 8

A planet - is a natural object that orbits a sun.

Answer 9

A planet must orbit around a star, have enough mass for gravity to make it nearly round, and have cleared its orbital path of other debris to be classified as a planet.