Earth Will Be Farthest From The Sun On July 7. Know The Exact Timing, And The Science Behind The Event

When Earth reaches aphelion, it will be at a distance of 15,20,93,251 kilometres from Earth. This is almost equal to 152.1 million kilometres. 

Every year, Earth reaches aphelion in July, a few days after summer solstice in the Northern Hemisphere, and winter solstice in the Southern Hemisphere. 

Source : NASA

Earth will be at its farthest from the Sun on Friday, July 7. This is because the Blue Planet will be at aphelion, which refers to the point in the orbit of a celestial body most distant from the Sun. This year, Earth will reach aphelion at 20 UTC on July 6 (1:30 am IST on July 7), according to Earth Sky. The planet will be at a distance of 15,20,93,251 kilometres from Earth. This is almost equal to 152.1 million kilometres. 

Every year, Earth reaches aphelion in July, a few days after summer solstice in the Northern Hemisphere, and winter solstice in the Southern Hemisphere. 

The word aphelion is derived from the Greek words apo, which means away or apart, and helios, which is the Greek God of the Sun. Therefore, aphelion means "apart from the Sun". 

The science behind aphelion

Since Earth orbits the Sun in an elliptical orbit, there is a point closest to the Sun, and a point farthest away from the Sun. 

The gravitational influences of other planetary objects, including the Moon, cause the shape of Earth's orbit around the Sun to change. The path changes from being nearly circular to elliptical, every 100,000 years, according to timeanddate.com. 

The difference between an ellipse and a perfect circle is called eccentricity. Therefore, a perfect circular orbit has an eccentricity value of zero, while an elliptical orbit has an eccentricity value of 1. Therefore, the eccentricity of Earth's orbit changes every 100,000 years.

The dates when Earth reaches its aphelion and perihelion, the point in the planet's orbit nearest to the Sun, are not fixed due to variations in the eccentricity of Earth's orbit. About eight centuries back, in 1246, the day of December Solstice and the day Earth reached perihelion were the same. Every 58 years since 1246, the dates of perihelion and aphelion have drifted by a day. 

In some cases, there can be a difference of two days between the dates of perihelion or aphelion in two consecutive years. 

More than 4,000 years from now, in 6430, the perihelion will coincide with the March Equinox, the beginning of astronomical summer in the Northern Hemisphere, according to astronomers. 

Apogee is another word for aphelion.

Aphelion will occur on July 5 in 2024, on July 4 in 2025, July 6 in 2026, and July 5 in 2027.