Right now, the northern hemisphere is in the dead of winter, which means it's cold. The winter solstice has just ended, which means it gets dark very early and stays that way far into the morning. And yet, at 2:19 a.m. ET on January 2, Earth slid by the perihelion—the point at which our planet is as close as it gets to the sun.
Earth passes the perihelion every January and the aphelion (the point at which we're farthest away from the sun) every July.
** MERRY PERIHELION ** Overnight January 2 / 3, Earth at Perihelion: The closest distance to the Sun in our annual… https://t.co/3exn51eErP— Neil deGrasse Tyson (@Neil deGrasse Tyson)1546451880.0
Nottingham Trent University astronomer Daniel Brown joked on Twitter about the perihelion, calling the day's sun a "super sun" (referencing how we call the moon a "super moon" when its at its perihelion).
It's here! This year's SUPER SUN. 😮😮 When it rises it will be appear the biggest this year. 4% larger than in July… https://t.co/bHqveKdzFw— Daniel Brown (@Daniel Brown)1546500886.0
@AstronomyMag Wow the earth is going to be on fire. Hurry build space station so i can finally go where no man has gone before.— Sweet love (@Sweet love)1546508809.0
For those who don't remember from science class, the earth's distance from the sun is constantly changing due to the fact that its orbit isn't circular—it's elliptical, with the sun at one of the ellipse's focal points.
@AstroDanNTU @SophiaCentre @fraumichel1 @FSilva_Archaeo Nobody expects(notices) a super sun - British folks in wint… https://t.co/bP2Ft7INTR— Jill Arnold (@Jill Arnold)1546513096.0
Similarly, though it seems counter-intuitive for the planet to be extra close to the sun just as things are extra cold, Earth's seasons are caused by the tilt of its axis rather than its proximity to heat. During the winter, the northern hemisphere is tipped away from the sun's light, causing winter, while the southern hemisphere is tipped towards, receiving more direct sunlight, which causes summer.
Happy Perihelion Day Thursday! That's the day Earth is closest to the sun at 91 million miles away. We are farthest… https://t.co/f5TQqIdVZz— Wes Hohenstein (@Wes Hohenstein)1546461273.0
@neiltyson This so confuses my 8th grade science students 🤔 Why cold then they ask. Because northern hemisphere ti… https://t.co/yDnPNsZC0Z— Toby Baugher (@Toby Baugher)1546454455.0
On Twitter, science-fans everywhere were wishing each other a Merry Perihelion!
@neiltyson I prefer this one. 😁 https://t.co/ubv74tSv8W— Carlos Pazos (@Carlos Pazos)1546502687.0
@neiltyson Merry Perihelion!— Lawrence E. Jahn (@Lawrence E. Jahn)1546572462.0
@neiltyson https://t.co/fZlyrYbmHl— spontane (@spontane)1546463077.0
@neiltyson What a joyous event! How will you be celebrating? 🥳— Eleanor Dennison 🐻 (@Eleanor Dennison 🐻)1546455799.0
@neiltyson So glad we can say Merry Perihelion!— Mr. Hobbes (@Mr. Hobbes)1546455780.0
Meanwhile, Bob Henson, a meteorologist writing for Weather Underground, wrote for Weather Underground that our orbit around the sun isn't completely stable, and our dates of perihelion and aphelion are drifting forward ever so slightly:
"In addition, these date ranges of perihelion and aphelion are also sliding forward on the calendar ever so gradually—less than two days per century—as Earth's tilt itself undergoes a slow-motion wobble. In 13,000 years, perihelion will be arriving in July and aphelion in January."
The sun itself also experiences cycles of activity and non-activity. It's now entering a phase known as the solar minimum, where sun spots fade and the star remains relatively "quiet." This inactivity should come to a "peak" around 2020 before heading back towards a solar maximum in 2024.
Earth just made its closest approach to the Sun as we enter the solar minimum https://t.co/fWYE5lNvnt https://t.co/RuiSw1uIP9— Newsweek (@Newsweek)1546511404.0
Happy Perihelion, everybody! May we grow even closer to the sun next year?
Happy Perihelion! You won’t be any closer to the Sun this year. https://t.co/XFPenkabjW— Mr. Showell (@Mr. Showell)1546458416.0