Is the moon a planet
Further, the Moon is a satellite not a planet because it does not satisfy IAU’s “definition of a planet.” IAU stands for International Astronomical Union.
| Conditions for to be a Planet | Moon |
|---|---|
| It must revolve around a “star” | It revolves around “Earth” (which is a planet not a star) |
| It needs to be sufficiently big such that its gravity can keep it into a “spherical shape” | The Moon has an egg-like form; it is not spherical/circular. The Moon’s mass is about 1/80th (or roughly 1.2%) of Earth’s mass. The width of the Moon is around “one-fourth” (or a quarter) that of Earth. The moon has a lesser gravitational pull — roughly one-sixth that of Earth |
| It must have cleared its orbital path from “asteroidal debris” and objects of similar size | The Moon has not ‘cleared its orbit’; there are still things that are ‘approaching or crossing’ its orbit, including “meteoroids, space debris, and occasionally asteroids.” The Moon is continuously hit by space debris and meteorites. On average, the Moon is impacted by meteoroids about once a month |
Moreover, there are no moons of the Earth’s Moon. Also, the Earth’s Moon is ringless.
Earth has one moon, Mars has 2, Jupiter has 95, Saturn has 146, Uranus has 28, Neptune has 16, and Pluto has 5 moons. Only few of them are named here.
| Planet | Satellite |
|---|---|
| Earth | Moon |
| Mars | Deimos |
| Mars | Phobos |
| Jupiter | Adrastea |
| Jupiter | Amalthea |
| Jupiter | Callisto |
| Jupiter | Europa |
| Jupiter | Ganymede |
| Jupiter | Himalia |
| Jupiter | Io (EYE-oh) |
| Jupiter | Metis |
| Jupiter | Thebe |
What is a planet -
Three requirements are listed in the International Astronomical Union’s (IAU) “definition of a planet”:
- It must revolve around a “star” (e.g., the Sun, in our cosmic neighborhood).
- It needs to be sufficiently big such that its gravity can keep it into a “spherical shape” (known as a ‘hydrostatic equilibrium’ (almost round) state).
- It must have cleared its orbital path from “asteroidal debris” and objects of similar size. By “clearing the orbit,” we mean that no other bodies of similar size share its orbit around the Sun because its gravitational pull has either ‘absorbed or destroyed’ other objects from its neighborhood.
The IAU also declared that planets and other entities in our Solar System — aside from satellites — should be divided into three different groups: planets, “dwarf planets,” and “small solar system bodies.”
What is a Satellite -
Anything that orbits a “bigger” object is called a satellite. A ‘moon, planet, or spacecraft’ in orbit around a ‘star or planet’ is called a satellite.
The moon orbits Earth, making it a satellite. The moon orbits the earth through balance of the combined effects of “centrifugal force, velocity, and gravitational pull.”
The earth orbits Sun, making it a satellite. The moon and earth are referred to as “natural” satellites. Also, Earth is orbited by thousands of ‘artificial or man-made’ satellites.
“Planetary satellites” are naturally occurring celestial bodies that orbit planets. The Moon rotates on its own axis at the same speed as it revolves around the Earth (synchronous rotation), by which the same ‘hemisphere’ is always facing Earth.
While some “planetary moons” are captured objects that originated elsewhere and ‘absorbed into orbit around the planet,’ the majority most likely formed from the discs of gas and dust circling planets in the early solar system.
*the aforesaid data came from “science.nasa.gov/solar-system/planets/what-is-a-planet/”, “science.nasa.gov/solar-system/moons/”, “ssd.jpl.nasa.gov/sats/”, “science.nasa.gov/mission/ladee/outcome/”, etc.
That’s all friends.
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