Category Science

What are the “Morning Star” and the “Evening Star”?

Mercury and Venus, due to their inferior orbits, always appear close to the Sun and are difficult to see except in the Twilight hours. Mercury and Venus are sometimes referred to as “Morning Star” and “Evening Star”. However, they are really not stars but planets.

Why did the ancients mistake the planets Mercury and Venus for stars?

Mercury and Venus appear bright during twilight hours when the stars are usually faint. Mercury is sometimes as bright as the bright-stars Sirius. Venus appears brighter than Mercury <sometimes even ten times brighter>.

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What are “Inferior” and “Superior” Planetary orbits?

Mercury and Venus are said to have inferior orbits due to their greater nearness to the Sun than Earth. The other planets which are farther from the Sun than Earth are said to have superior orbits.

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What is an Astronomical Unit?

An Astronomical unit (usually abbreviated as “a.u.”) is a unit of measurement of measuring distances in the Solar System one a.u is equal to 149,597,870 km which is the mean or average distance between the earth and Sun during the elliptical orbit on the earth around the Sun.

Do the planets orbit the Sun in the same plane?

Except Pluto, the entire planet orbit the Sun nearly in the same plane. The plane of the orbit of Pluto is titled by about 170 to the mean plane of orbit of then other planets.

Continue reading “The Solar System”

What is meant by “Inner” and “Outer” Solar System?

The Inner Solar System refers to the region between the Sun and Mars where the planets are relativity close together. Beyond this is the Outer Solar System, where the planets are spaced relatively wider apart.

What are the main constituents of the Solar System?

The solar System consists of the Sun and all the heavenly bodies that orbit it, such as the planets, moons, asteroids, comets, etc.

The term Solar System is also synonymously used to refer to the region of space occupied by the Sun and the other bodies of the Solar System.

Name the planets and their symbols.

The nine planets orbiting the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Sometimes specific symbols are used to denote the planets.

Can a Heavenly body be a temporary member of the Solar System?

Yes. For example, a comet following a hyperbolic trajectory can enter the Solar System, go around the Sun Partially and leave the Solar System never to return.

Are the names of the planets usually mentioned in ascending order of their distance from the Sun?

Yes, up to Uranus. Pluto has a highly eccentric orbit which partially overlaps the orbit of Neptune. Sometimes Pluto is the outermost planet and at other times Neptune is the outermost one.

 So all the planets orbit the Sun in the same direction?

Yes.

Do all the planets rotate about their own axes white orbiting the Sun?

Yes.

        Newton’s Laws of Motion are:

1. A body at rest or moving in a straight line continues to do so unless disturbed by an external force.
2. The rate of change of momentum (product of mass and velocity) of a body is directly proportional to the force applied to it and is the applied force.
3. For every action force (force A) there is an equal and opposite reaction force (force R).