Why summer arrives when Earth is farthest from the Sun: the Aphelion paradox

Even as record-breaking heat scorches much of the Northern Hemisphere, Earth is now farther from the sun than at any other time this year. On Thursday, July 3, at 3:55 p.m. ET, the planet reached its aphelion, the point in its orbit where it is farthest from the sun, roughly 3.1 million miles farther away than during its closest approach in early January.

And it continued to remain distant, so why is it still so unbearably hot if we're farther away?

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The answer may seem paradoxical and may not align with the common belief that the less the distance from a hotter object, the colder it is. But in reality, it is not in the planet’s distance from the sun but in how Earth is tilted.

It is Earth’s tilt

This axial tilt, not proximity, drives seasonal temperatures, and right now, the Northern Hemisphere is leaning directly into the sun’s rays.

Earth’s 23.5-degree axial tilt is the primary driver of seasonal changes, not its distance from the sun.

During July, the Northern Hemisphere is tilted toward the sun, resulting in longer days, more direct sunlight, and thus higher temperatures.

Despite being farther from the sun, cities like New York, Phoenix, and Denver are experiencing intense summer heat due to the sun’s high angle in the sky, which delivers concentrated solar energy.

Orbit shape plays a minor role

Earth's orbit around the sun is slightly elliptical, but the variation is relatively small, just a 3.3 per cent difference between aphelion and perihelion (its closest point, in early January).

This leads to a modest 7 per cent reduction in solar energy reaching Earth during aphelion, a minor factor compared to the effect of Earth's axial tilt.

In fact, solar energy in places like Columbus or Houston more than doubles between winter and summer, with levels jumping from about 145 watts to 430 watts per square meter, a nearly 300 per cent increase, due entirely to seasonal angles rather than proximity.

In essence, Earth’s hottest season in the north doesn’t result from closeness to the sun but from the angle at which sunlight hits the planet. The sun’s rays strike more directly during summer, heating land and the atmosphere more efficiently.

So, as strange as it sounds, Earth’s aphelion arrives right as many in the Northern Hemisphere sweat through the hottest days of the year, all because of the planet’s tilt.