Question

There are nine planets in the solar system.
A) True
B) False

Answer 1

A celestial body can be called a planet if it fulfils the following criteria: It must orbit a star (in our cosmic system, it is the sun). It must have enough mass to have enough gravity which forces it into a spherical shape.

Step-by-step solution:
Since the discovery of Pluto in 1930, it was known to us that our solar system has nine planets. In the late 1990s, astronomers started arguing about whether Pluto was indeed a planet. Based on the argument the International Astronomical Union ultimately decided to designate Pluto as a "dwarf planet," in 2006. It reduced the list of the solar system's true planets to just eight.

The order of the planets according to the distance from the sun, in order nearest to farthest; the eight planets in our solar system are as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
The first known model of the solar system that placed the Sun at the center of the known universe with the Earth revolving around it was presented by Aristarchus of Samos in the third century BCE, but it was not generally accepted. In16th century, the idea of the Sun at the center of the universe was revived by Nicolaus Copernicus.
In 2006, the IAU passed a resolution that defined the planet and established a new category, dwarf planet. And Pluto was categorized under the category of dwarf planet in 2006.

Therefore, our solar system consists of only eight planets.

Hence, the statement given is false.

Note:
-The number of planets can be changed if astronomers find any new planet.
-The celestial body must have all the characteristics to be called the planet, like it must revolve around a star and must have enough gravity which can shape it like a sphere (need not be a perfect sphere).