Naturally, this brightest Sun cannot make up for its anemic lack of height in the sky. Its rays hit the ground at an oblique angle and are spread out and weakened, compared with solar strength when it’s high up. Still, the current brighter Sun makes our winters more moderate than they’d otherwise be.
In the Southern Hemisphere – enjoying summer right now – the added boost of having this seven-percent-greater Sun intensity should theoretically make seasons more extreme than ours, with hotter highs and colder lows. It doesn’t happen only because they have far more oceanic acreage. Water moderates temperatures, so that the two hemispheres, remarkably, have all factors balancing out.
To put real numbers on it, we’re now just 91 ½ million miles from the Sun, compared to the 94.8 million gap in July. That’s a difference of 3 1/3 million miles.
Besides the brighter Sun, we get other noticeable effects. Planets are whipped to faster orbital speeds when nearest the Sun, so that Earth now zooms along at a zippy 67,000 miles an hour compared to our summertime speed of 65,000. This 2,000-mph boost carries us more quickly through this depressing section of our orbit where our northern axis points anti-sunward, getting this chilly experience over with more rapidly. It hastens the end of winter, just as our slowest orbital speed from June through August extends summers. This is why our summers are five days longer than our winters.
There’s still more. By moving faster, the time from true solar noon – when the Sun is on the meridian and highest up – to the next day’s noon is longer by 16 seconds a day compared to July. Our planet has to spin around just a bit more these days to reach the place where it once again perfectly faces the Sun, whose position against the stars has shifted most rapidly due to our currently fast orbital motion. In other words, the day’s unvarying clock length of exactly 24 hours now maximally differs from the actual time between subsequent solar noons.
This correction appears on sundials, in case you frugally keep time that way. It’s also marked on globes in the form of a figure-eight called the analemma. It adds up, and helps make clock time and sundial time differ by about 15 minutes at a couple of occasions every year. It also explains why our earliest sunset is on December 7, while the darkest mornings (latest sunrises) are delayed until the first week of January. It’s because our clocks annually go out of synch with the Sun.
Lots of consequences – good ones – largely because our orbit isn’t round. Happy Perihelion!
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