On January 2, 2021, Earth will be closer the sun in its elliptical orbit than on any other day of the year, marking an annual event known as perihelion.
The word perihelion is translated from Ancient Greek and means “near the sun”. According to EarthSky, Earth was expected to reach perihelion on Saturday morning at 8:41 a.m. ET.
The sun is about 3% bigger in the sky on Saturday – not enough to see with the naked eye. Remember, you should never look at the sun without proper eye protection, and sunglasses are not a sufficient substitute for sunglasses.
Earth’s orbit is not a perfect circle, which means that sometimes the planet is a little closer to our star and sometimes further away. Its distance varies by about 3 million miles over the course of the year – almost 13 times the distance from Earth to the Moon.
Perihelion also marks the moment when the Earth moves fastest in its orbit around the sun. The planet is currently racing around the sun at nearly 30 kilometers per second – about 0.6 miles per second further than when it reached its farthest point from the sun in July.
“If you run east locally at midnight, move as fast as you can (at least in coordinates in the center of the sun) for your location,” NASA said.
As a result, summer in the northern hemisphere lasts about five days longer than winter, according to EarthSky. The opposite is true in the Southern Hemisphere.
Although the sunlight is more intense on Saturdays, winter in the Northern Hemisphere is unaffected by the Earth’s 23.5 degree tilt. When you are closer to the sun, the tilt of the Earth does not change, so the north pole is still away from the sun.
In six months, on July 5, the Earth will be furthest from the sun, known as its aphelion, meaning “far from the sun.” At perihelion, the earth is about 147.5 million miles from the sun and about 94.5 million miles from aphelion.
Between perihelion and aphelion there is a difference of about 6.7% in the intensity of the sunlight hitting our planet. According to NASA, this explains more extreme seasons in the Southern Hemisphere compared to the Northern Hemisphere.
The perihelion isn’t the only celestial event this weekend. Saturday evening through Sunday morning also marks the peak of the Quadrantid meteor shower – one of the best of the year.