What are perihelion and aphelion?
The perihelion is the point in the orbit of the Earth, or any planet, comet, asteroid, or orbiting object, where it is closest to the sun
The aphelion is the opposite, the point in the orbit when the object is farthest from the sun
Most orbiting bodies have elliptical orbits, not circular orbits, therefore the bodies are not a fixed distance from the sun at all times.
Here, (1) is the aphelion, (2) is the perihelion, and (3) is the sun (not to scale).
The distance of the Earth to the Sun is:
147.1 million km (91.4 million miles) at perihelion in early January
152.1 million km (94.5 million miles) at aphelion in early July
Both words come from Greek, where 'peri' means 'near', and 'Helios' is the Greek god of the sun, and 'apo' means 'away'.
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Perihelion is the point in an object's orbit around the Sun where it is closest to the Sun. Aphelion is the opposite, representing the farthest point from the Sun in an object's orbit.
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When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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