Solar Energy – JNNSM, Solar Cities, Solar Pumps, etc.

What is Aphelion?


From UPSC perspective, the following things are important :

Prelims level: What is Aphelion?

Mains level: Does aphelion affect temperatures on Earth?

Why in the News?

Early on July 5, the Earth reached aphelion, its farthest distance from the sun in our year-long journey around our nearest star.

What is Aphelion? 

  • Aphelion is a term used in astronomy to denote the point in the orbit of a planet or celestial body where it is farthest from the Sun. 
  • The Earth’s orbit around the Sun is not a perfect circle but rather an ellipse, with the Sun situated at one of the two foci of the ellipse. 
  • Aphelion marks the moment when Earth is at its maximum distance from the Sun along this elliptical path.
  • The concept of aphelion was crucial in Johannes Kepler‘s formulation of his laws of planetary motion during the 17th century.

How far is the Earth from the Sun at aphelion? 

  • At aphelion, which occurs around July 4th– 5th each year, the Earth is approximately 152.1 million kilometers (about 94.5 million miles) away from the Sun. 
  • This distance is about 3.3% greater than its average distance from the Sun, known as its semi-major axis, which is about 147.1 million kilometers.

Does aphelion affect temperatures on Earth? 

  • Aphelion has a slight effect on temperatures on Earth, but its impact is minimal compared to other factors such as axial tilt and atmospheric circulation patterns. 
  • Despite being farther from the Sun during aphelion, the Earth’s tilt towards the Sun during the northern hemisphere’s summer results in warmer temperatures for that region. 
  • This phenomenon is primarily responsible for the seasons on Earth.

What would happen if there were no aphelion? 

  • If Earth’s orbit were perfectly circular, without aphelion or perihelion (the closest point to the Sun), the distance between Earth and the Sun would remain constant throughout the year. 
  • This scenario would result in less variation in seasonal temperatures between the northern and southern hemispheres. 
  • The distinct seasons that we experience today, which are essential for ecological diversity and agricultural cycles, would be significantly altered.

[2013] Variations in the length of daytime and night time from season to season are due to-

(a) The earth’s rotation on its axis

(b) The earth’s revolution round the sun in an elliptical manner

(c) Latitudinal position of the place

(d) Revolution of the earth on a tilted axis



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