Earth closest to sun on January 3-4
Earth at perihelion in January
Earth’s orbit around the sun isn’t a circle. Earth’s orbit around the sun isn’t a circle. Instead, it’s an ellipse. So it makes sense that Earth swings closest to the sun once each year. For 2022, that moment happens at 6:52 UTC (12:52 a.m. CST) on January 4 … tonight for us in North America. This closest Earth-sun distance is called perihelion, from the Greek roots peri meaning near and helios meaning sun. In early January, we’re about 3% closer to the sun – roughly 3 million miles (5 million km) – than we are during Earth’s aphelion (farthest point from the sun) in early July. That’s in contrast to our average distance of about 93 million miles (150 million km).
So Earth is closest to the sun every year in early January, when it’s winter for the Northern Hemisphere.
And we’re farthest away from the sun in early July, during our Northern Hemisphere summer.
Earth’s orbit doesn’t cause seasons
So Earth’s orbit isn’t a circle. But it’s very nearly circular. And it’s not our distance from the sun that creates winter and summer on Earth. Instead, it is the tilt of our world’s axis that causes seasons.
In winter, your part of Earth is tilted away from the sun. In summer, your part of Earth is tilted toward the sun. The day of maximum tilt toward or away from the sun is the December or June solstice.
Earth’s orbit slightly affects length of the season
Though not responsible for the seasons, Earth’s closest and farthest points to the sun do affect seasonal lengths. When the Earth comes closest to the sun for the year, as we do every year in early January, our world is moving fastest in orbit. Earth is rushing along now at almost 19 miles per second (30.3 km/sec), moving about 0.6 miles per second (one km/sec) faster than when Earth is farthest from the sun in early July. Thus, the Northern Hemisphere winter and – simultaneously – the Southern Hemisphere summer are the shortest seasons as Earth rushes from the solstice in December to the equinox in March.
In the Northern Hemisphere, the summer season (June solstice to September equinox) lasts nearly five days longer than our winter season. And, of course, the corresponding seasons in the Southern Hemisphere are opposite. Southern Hemisphere winter is nearly five days longer than Southern Hemisphere summer.
The 30-second YouTube video below illustrates how a planetary body speeds up around perihelion and slows down at aphelion. It’s due to Kepler’s second law of planetary motion: a line connecting the sun and a planet sweeps out equal areas in equal times.
Bottom line: In 2022, Earth’s perihelion, its closest point to the sun, is on January 4 at 06:52 UTC.