Question

What do the terms perihelion and aphelion mean and how are they related?

Answer 1

Hint: The point of the Earth's orbit that is far away from the sun is called Aphelion and the point of the Earth's orbit that is nearer to the sun is called Perihelion.

Complete step by step answer:
We know that the Earth orbits the sun in an elliptical path which is oval. As the sun is not at the center of the elliptical orbit, the planets while orbiting moves closer towards the sun and moves farther away from the sun. Thus the place at which the planet is closer to the sun is called Perihelion and the place at which the planet is farther from the sun is called aphelion.
The southern hemisphere is in summer at perihelion and thus receives more sunlight as it is more closer to the sun also the southern hemisphere being the ocean, will retain the heat during the winter months. Similarly, the northern hemisphere will be warmer.
The distance of the aphelion between the Earth’s and Sun’s center is 152,097,700 km or 101671 Astronomical Units. The dates of aphelion and the perihelion will change from time to time mainly due to the precession and also due to other orbital factors that follow the cyclical patterns called Milankovitch cycles.

Note:
1. The Earth’s orbit around the sun will change its shape every 100,000 years. It may become either more round or more elliptical during these intervals.
2. The shape of the orbit is called eccentricity. At present, the Earth’s orbital eccentricity is about 0.0167 which indicates the orbit is closer.