Question

Which of the following criteria do astronomers use to classify an object as a planet? orbits a star gravity makes spherical at least as large as mercury clears orbits of other objects

Answer 1

The correct answer is Orbits a star, gravity makes it spherical, and clears orbits of other objects. Planets can be smaller than mercury so it's not a criterium.

Answer 2

The correct answer of the question is : A) Orbits a star, B) Gravity makes spherical and D) Clear orbits of other objects.

EXPLANATION :

The classification of a celestial object to be a planet depends on some parameters.

The most important thing about the planet is that it must clear its orbit. It means it won't share its orbit with other planets. Otherwise, it will be considered as a dwarf planet.

The second thing is that it must move around any stars. The star becomes the centre of that solar system around which planets start revolving in different orbits.

The third thing is that planets are approximately spherical in shape.

The size of the planets does not play a crucial role in the classification of planets. Planets may be smaller than mercury also.

Hence, all the options except the third one are suitable.