The year 2018 isn’t even a day old yet, but we’re already bathing in the most intense sunlight of the year. That’s because tomorrow Earth will be closest to the Sun for the year — a million and a half miles closer than the average distance of 93 million miles. That means that the amount of solar energy Earth receives at this time of year is a few percent greater than average.
The distance changes because Earth’s orbit is an ellipse — like a slightly flattened circle. All the planets follow elliptical paths around the Sun. Venus’s is the most nearly circular, while Mercury’s is the most lopsided.
You might expect Earth to warm up when it’s closest to the Sun, but that’s not really the case. Our planet does a good job of keeping the temperature about the same all year ’round. The atmosphere, oceans, and ground absorb the extra heat when we’re close to the Sun, and release it when we’re farther away.
The varying distance does affect the amount of energy produced by solar panels — how much sunlight they receive determines how much electricity they produce. Of course, the situation is complicated by other factors. At northern latitudes, for example, the Sun is lowest in the sky for the year right now, so it doesn’t shine as directly on the panels at those locations. The sunlight also has to pass through a thicker layer of air, so more of it is absorbed before it reaches the ground — a real-world challenge presented by our varying distance from the Sun.
Script by Damond Benningfield