Happy Aphelion Day, what? Earth is farther from the sun than any other day of year

Time machine concept with elements furnished by NASA | Composite image by Lukaves, iStock/ Getty Images Plus, St. George News

ST. GEORGE — It’s “Happy Aphelion Day,” an annual event when the earth is at its greatest distance from the sun, which may be surprising to Southern Utahns with triple-digit temperatures scorching the region Friday.

Earth’s annual orbit around the sun carried it to its furthest point from its star, its aphelion, Friday at 10:46 MDT, according to Space.com. At that moment Earth was more than 94.5 million miles from the sun, which is about 1.5 million miles farther than the third planet’s average distance, or twice as far away as it was Jan. 3 during the perihelion, when Earth was closest to the sun. That is about a 2 percent difference in distance, an inestimable amount in the cosmic scheme of things.

Infograph depicting Earth’s orbit at aphelion, when it is farthest from the sun and its perihelion | Image courtesy of NASA, St. George News

Consistent with all planets in the solar system, Earth has an elliptical, or oval, orbit around the sun that is located 1.5 million miles off-center.

As such, all planets have a point where they are closer to the sun, or the perihelion, and a point of farthest approach, the aphelion.

The aphelion typically falls two weeks after the June solstice, which marks the first day of summer on the Northern Hemisphere and winter on the Southern Hemisphere.

Johannes Kepler, a 16th century mathematician, was the first to discover that the orbits of the planets were ellipses, or oval-shaped paths the planets take around the sun, according to an information sheet published by the University of Oregon.

Kepler also concluded that orbiting objects sweep out equal areas in equal times, so they are faster at perihelion and slowest at aphelion.

There will be no noticeable difference here on Earth, as NASA scientists say that seasons are “shaped primarily by the 23.5-degree tilt of the planet’s spin-axis and not by the mild eccentricity of Earth’s orbit,” George Lebo, an astronomer with NASA’s Marshall Space Flight Center in Huntsville, Alabama, said in a 2001 interview – the year Kepler’s defined aphelion fell on the Fourth of July.

This 2014 NASA image shows Earth over Brazil taken from the International Space Station, June 12, 2014 | Image courtesy of NASA, St. George News

In other words, the earth is lopsided.

Days are longer during summer months as Earth’s North Pole tilts toward the sun and sunlight is directed downward, Lebo said, “more nearly straight down.”

Strangely, sunlight hitting Earth July 6 is less intense than during the perihelion in January, when Earth is closest to the sun – about 7 percent less. This is because most of the sunlight in July is hitting land on the Northern Hemisphere, due to the Earth’s tilt, which is an elliptical orbit, has a lower heat capacity because dirt and rocks aren’t in motion; they are stationary and those materials heat up more quickly.

Water, on the other hand, has a high heat capacity that comes from the ability to store heat, which in turn moderates the underwater environment.

It may seem contradictory with July being the hottest month on a planet that is farther away from the sun than at any other point in the year. Likewise, in January the situation is reversed when Earth is closest to the sun but will be cooler, thanks to its water-dominated hemisphere facing the sun.

Email: cblowers@stgnews.com

Twitter: @STGnews

Copyright St. George News, SaintGeorgeUtah.com LLC, 2018, all rights reserved.

 

 

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24 Comments

  • IPFreely July 6, 2018 at 4:33 pm

    Holy crap… this did not occur by chance. The universe was created and is sustained by a higher power.

    • John July 6, 2018 at 5:24 pm

      B&F will argue with you… be careful..hahahahahahahahahaha!

      • comments July 7, 2018 at 12:19 am

        blah blah blah. Still doesn’t make your BOM or your HOLY BUYBULL anything more that a bunch of fairytales. IP and john: 2 man clown circus, hahaha 😉

        • IPFreely July 7, 2018 at 8:34 am

          Geez… anger management dude

        • John July 7, 2018 at 9:24 am

          Go away failed mormon.. damn you are one bitter ignorant old fool!

          • comments July 7, 2018 at 1:11 pm

            that’s not very xtian of you to say johnno. Aren’t you hypocrites supposed to “bring in the lost sheep”? hahahahah 😉

          • John July 7, 2018 at 2:59 pm

            I’m not the failed mormon “bob”.. you just couldn’t cut the funeral potatoes..hahahahahahahaha! You’re not even good at being a troll.. LOSER!

          • IPFreely July 7, 2018 at 4:09 pm

            Coma has a problem. He is angry at the world and has to lash out at everything

          • comments July 7, 2018 at 4:12 pm

            I’m sorry John. Truth is I am angry at myself because I didn’t get my way as a child and wanted so much for the mailman to hug me

    • Chris July 7, 2018 at 12:16 pm

      You are correct that it did not occur by chance. It occurs according to Newtonian mechanics and can be predicted quite precisely with an elementary knowledge of physics and calculus. How you get from that to “a higher power” is anything but precise.

      • John July 7, 2018 at 12:57 pm

        Chrisp, and Newtonian mechanics were created by that same higher power, so nice of you to agree….

      • John July 7, 2018 at 1:02 pm

        Chrisp, I’d like to add, Newtonian Mechanics is just one way humans try to explain the workings of that “higher power”.. Think about it, If you can wrap your mind around it for a minute..

        • comments July 7, 2018 at 5:28 pm

          But that’s not logical I can’t trust or have faith in anything not logical and can’t be proven by humans. My brain is only so small

          • John July 7, 2018 at 10:08 pm

            we know..hahahahaha!

      • IPFreely July 7, 2018 at 4:08 pm

        Hahaha… just because we have a name for it. Who created the power? Huh huh

        • comments July 7, 2018 at 6:21 pm

          Still doesn’t make your BOM or you BUYBULL true, clown circus

          • IPFreely July 7, 2018 at 7:41 pm

            I never said it did, but you would just assume

  • comments July 7, 2018 at 6:22 pm

    Looks like someone made a little “comments” clone troll account. You people are absolutely adorable <3 😉

    • John July 7, 2018 at 10:09 pm

      your’e the original bob.. your’e the original. nobody is as miserable as you.!

      • comments July 7, 2018 at 11:04 pm

        hahaha. You nutters sure get touchy on topics of religion. 😉

        • IPFreely July 8, 2018 at 7:17 am

          Go find the mailman comments

      • John July 8, 2018 at 7:56 am

        your’e the one having a tantrum litte girl! waah waaah waaah! if you had half a brain you would be bikeandfish!

        • ladybugavenger July 8, 2018 at 12:41 pm

          Dont be mean to Bob and say something like that

          • John July 8, 2018 at 1:35 pm

            Laughing out loud…..Just pointing out the fact that he’s a crybaby loser and complains about everything. hahahahaha! Have a great day LBA!!!

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