The Earth is closest to the Sun (perihelion) every year around:

The Earth reaches perihelion, the point in its orbit nearest to the Sun, in early January, usually around 3 or 4 January.

Meaning of the term:

• "Perihelion" comes from the Greek words "peri" (near) and "helios" (Sun).
• Its opposite is aphelion ("apo" means away), the point in the orbit farthest from the Sun, which the Earth reaches in early July.

Distances:

• At perihelion, the Earth is about 147 million km from the Sun.
• At aphelion, it is about 152 million km away.
• The difference is only about 5 million km, or roughly 3 percent, because the Earth's orbit is nearly circular, with a low eccentricity of about 0.017.

Why the Northern Hemisphere has winter at perihelion:

• Many people think the Earth should be warmest when it is closest to the Sun, but seasons are not caused by distance.
• Seasons are caused by the tilt of the Earth's axis.

In early January, the Northern Hemisphere is tilted away from the Sun, so sunlight falls on it at a low angle and days are short. This makes it winter in the north, even though the Earth is nearest the Sun.

At the same time, the Southern Hemisphere is tilted towards the Sun and has summer.

Effect on the Earth's speed:

• According to Kepler's second law, a planet moves faster when it is closer to the Sun.
• So the Earth moves fastest around perihelion and slowest around aphelion.

Effect on sunlight:

The Earth receives about 7 percent more solar energy at perihelion than at aphelion.

Why not the other options?

• ✗4 July is around aphelion, when the Earth is farthest from the Sun.
• ✗15 April and 10 October are not linked with the Earth's nearest approach to the Sun.