On January 2, 2021, the earth is closer to the sun on its elliptical orbit than on any other day of the year, indicating an annual event known as perihelion.
The word perihelion is translated from the Ancient Greek, meaning “near the sun”. According to EarthSky, the Earth would reach perihelion on Saturday morning at 08:51 ET.
The sun is about 3% larger in the sky on Saturday – not enough to notice with the naked eye. Remember: never look at the sun without proper eye protection, and sunglasses are not a sufficient substitute for sunglasses.
The orbit of the earth is not a perfect circle, which means that the planet is sometimes a little closer to our star and sometimes further away. The distance varies over the course of the year by about 3 million miles – almost 13 times the distance from the earth to the moon.
Perihelion also indicates the moment when the Earth moves the fastest in its orbit around the sun. The planet is currently orbiting the sun at almost 19 miles per second – about .6 miles per second further than when it is its furthest point from the sun in July.
“If you run east at midnight, you will move to your place as fast as possible (at least centered in the coordinates of the sun),” NASA said.
As a result, summer in the Northern Hemisphere, according to EarthSky, lasts about five days longer than winter. The opposite is true in the Southern Hemisphere.
Although the sunlight is stronger on Saturday, the winter in the Northern Hemisphere is not affected, due to the 23.5 degree tilt of the Earth’s axis. Closer to the sun does not change the tilt of the earth, so the North Pole is still tilted from the sun.
Six months from now, on July 5, the earth will be the furthest from the sun, known as its aphelion, meaning “far from the sun.” At perihelion the earth is about 91.5 million miles from the sun, and at aphelion it is about 94.5 million miles away.
Between perihelion and aphelion, there is about 6.7% difference in the intensity of sunlight when it hits our planet. According to NASA, this is one explanation for more extreme seasons in the Southern Hemisphere compared to the Northern Hemisphere.
The perihelion is not the only heavenly event this weekend. Saturday night to Sunday morning is also the highlight of the Square meteor shower – one of the best of the year.