Distant Sun

To some otherwise intelligent northern hemisphere lifeforms it is counterintuitive, but the point at which Earth is furthest from the sun currently occurs during the summer. I say currently, as that point in Earth’s orbit – the aphelion – cycles over a timescale of around twenty-five thousand years, owing to a phenomenon known as apsidal precession.

This afternoon, Earth will be around five million kilometres further away from the heart of the solar system than at perihelion: the point of closest approach. That five million kilometres translates to a seven percent difference in the amount of sunlight falling on the Terran surface.

So what does this mean for weather and climate? Not a lot, as seasonal weather patterns are controlled largely by the tilt in out planet’s spin axis relative to its orbital plane. That tilt explains why northern summer equates to southern winter. On a global scale, Earth’s surface is on average a couple of degrees warmer at aphelion than at perihelion, and the reason for this has to do more with land mass and ocean distribution than orbital mechanics. There is more land in the northern hemisphere, and soil and rocks have a lower capacity than water for absorbing heat.

To understand this on a conceptual level, one could study pictorial representations of Earth’s orbit, and I recommend that you do. But a purely prosaic description has some value, and not just for those who like to boast of their ignorance of mathematics.