APHELION
1. Context
Behind elliptical orbits lies gravity. “All the planets tend to jostle each other around,” pulling their orbits from perfect circles, Runyon said. “It’s literally this chaotic tug of war between small amounts of gravitational influence that the planets have on each other.”
2. What is Aphelion?
- Aphelion is the point in the orbit of a planet, comet, or other celestial body where it is farthest from the Sun. For Earth, this occurs once a year, typically in early July. During aphelion, Earth is about 152.1 million kilometers (94.5 million miles) from the Sun. This distance is greater than the average Earth-Sun distance, known as an astronomical unit (AU), which is about 149.6 million kilometers (93 million miles).
- Aphelion is part of the concept of an elliptical orbit, described by Kepler's laws of planetary motion, where planets orbit the Sun in ellipses rather than perfect circles.
- The opposite of aphelion is perihelion, the point in the orbit where the celestial body is closest to the Sun. For Earth, perihelion occurs in early January.
- Despite being farther from the Sun during aphelion, the difference in solar energy received by Earth is relatively small and does not significantly affect the seasons, which are more influenced by the tilt of Earth's axis
- Elliptical orbits are governed by gravity. Planets exert gravitational forces on each other, causing deviations from perfect circular paths, explained Runyon. This interaction creates a chaotic gravitational tug-of-war among the planets.
- Jupiter has the strongest influence due to its massive size
- Eccentricity measures how much an orbit deviates from being circular. Higher eccentricity indicates a more elliptical orbit. Some solar system bodies have significant eccentricity: Mars has an eccentricity of 0.094, while Pluto's is 0.244. In contrast, Earth's eccentricity is relatively low at 0.017
3.What causes aphelion and when does it happen?
Aphelion is caused by the elliptical shape of Earth's orbit around the Sun. According to Kepler's laws of planetary motion, planets orbit the Sun in an ellipse rather than a perfect circle. This elliptical orbit means that there are points in Earth's orbit where it is closest to the Sun (perihelion) and farthest from the Sun (aphelion).
The gravitational interactions between Earth and other celestial bodies, particularly the other planets, also influence Earth's orbital shape, causing slight variations in its distance from the Sun throughout the year.
Aphelion occurs once a year, typically in early July. During aphelion, Earth is about 152.1 million kilometers (94.5 million miles) from the Sun, which is the farthest point in its orbit
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How far are we from the sun at aphelion?
At aphelion, Earth’s distance from the sun is about 94.5 million miles. Six months later, at the start of January in the winter, Earth is at its closest point to the sun at 91.5 million miles. This location is known as perihelion
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4.What is Perihelion?
Perihelion is the point in the orbit of a planet, comet, or other celestial body where it is closest to the Sun. For Earth, perihelion occurs once a year, typically in early January. During perihelion, Earth is about 147.1 million kilometers (91.4 million miles) from the Sun, which is closer than the average Earth-Sun distance, known as an astronomical unit (AU), which is about 149.6 million kilometers (93 million miles).
Key points about perihelion include:
- It is part of the elliptical orbit of celestial bodies, as described by Kepler's laws of planetary motion.
- The variation in distance between perihelion and aphelion (the farthest point from the Sun) is due to the gravitational forces exerted by the Sun and other celestial bodies
- During perihelion, Earth receives slightly more solar energy than at aphelion, but this difference does not significantly affect the seasons, which are primarily influenced by the axial tilt of Earth
- The point where Earth is farthest from the Sun, occurring in early July
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For Prelims: Aphelion, Perihelion
For Mains: GS III -Elliptical Orbits, Kepler’s Laws of Planetary Motion
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Source: Indianexpress
