Happy Perihelion Day

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  • Member since
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  • From: PA, USA, Earth Moderator
Happy Perihelion Day
Posted by DaveMitsky on Saturday, January 04, 2014 9:17 PM

The Earth was at perihelion (147,104,781 kilometers or 91,406,673 miles distant from the Sun) at 12:00 UT today.   At perihelion, the Earth is about 3% (5.0 million kilometers or 3.1 million miles) closer to the Sun than at aphelion. 

http://earthsky.org/tonight/earth-comes-closest-to-sun-every-year-in-early-january

The latest sunrise of 2014 at latitude 40 degrees north also occurred today.
 
Dave Mitsky 

Sic itur ad astra!

Chance favors the prepared mind.

A man is a small thing, and the night is very large and full of wonders.

  • Member since
    May, 2007
Posted by Bullfox on Sunday, January 05, 2014 10:50 AM

Dave,

How much does perihelion day change from year to year?

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  • From: PA, USA, Earth Moderator
Posted by DaveMitsky on Sunday, January 05, 2014 2:34 PM

Sic itur ad astra!

Chance favors the prepared mind.

A man is a small thing, and the night is very large and full of wonders.

  • Member since
    May, 2007
Posted by Bullfox on Sunday, January 05, 2014 8:30 PM

Fascinating!  I would have thought it progresses backward or forward over time in a consistant way instead of oscillating over time.

  • Member since
    May, 2005
Posted by Centaur on Sunday, January 05, 2014 9:50 PM

Bullfox

Fascinating!  I would have thought it progresses backward or forward over time in a consistant way instead of oscellating over time.

The oscillation is due to the influence of the Moon. If perihelion were measured relative to the Earth-Moon barycenter, then modest jumps would mainly reflect our point in the four-year leap year cycle. Although there would be a slow progression of the date over the long run. As it is, the position of the Moon significantly affects the date on which the Earth reaches perihelion.

For astronomical graphics, including monthly wallpaper calendar, visit:

www.CurtRenz.com/astronomical


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