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Earth's orbit, closest to the sun in January and furthest away...?

 
 
Reply Sun 22 Jun, 2014 12:24 pm
What? Earth's orbit, closest to the sun in January and furthest away in
July? Isn't Janaury cool (or cold) while July hot?
Yet closest to the sun keeps cool and furthest stays hot? It goes against common sense.
What do you think?

Context:

zone at all, even at its closest approach to the sun, which it reaches
once every 560 Earth years. The temperature of Halley's Comet
varies between about 47!C at perihelion and minus 270!C at
aphelion. Earth's orbit, like those of all the planets, is technically an
ellipse (it is closest to the sun in January and furthest away in
July*);
but a circle is a special case of an ellipse, and Earth's orbit
is so close to circular that it never strays out of the Goldilocks zone.
Earth's situation in the solar system is propitious in other ways that
singled it out for the evolution of life. The massive gravitational
vacuum cleaner of Jupiter is well placed to intercept asteroids that
might otherwise threaten us with lethal collision. Earth's single
relatively large moon serves to stabilize our axis of rotation, and
helps to foster life in various other ways. Our sun is unusual in not
being a binary, locked in mutual orbit with a companion star. It is
possible for binary stars to have planets, but their orbits are likely
to be too chaotically variable to encourage the evolution of life.
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chai2
 
  2  
Reply Sun 22 Jun, 2014 12:57 pm
@oristarA,
The difference between the two is 5,003,451 km, (3.3 percent), and not enough to cause the seasons. Even though, at this time of year, we're as close to the Sun as we can get, for the Northern Hemisphere, it will always be winter.

http://www.space.com/3304-earth-closest-sun-dead-winter.html

The change in seasons has to do with the tilt of the sun, not how close it is.

Remember however, in the Southern Hemisphere Summer is in January, and Winter is in July (or thereabouts)
Setanta
 
  1  
Reply Sun 22 Jun, 2014 01:10 pm
@chai2,
No, it has to do with the tilt of the Earth. The Earth's axis is not perpendicular to the plane of the ecliptic--it tilts at a 23 1/2 degree angle, and that is why we have seasons.
Setanta
 
  1  
Reply Sun 22 Jun, 2014 01:15 pm
This thread on the solstices explains both the seasons and our positions relative to the sun--perihelion (near the sun) and aphelion (far from the sun).
0 Replies
 
chai2
 
  1  
Reply Sun 22 Jun, 2014 01:17 pm
@Setanta,
Setanta wrote:

No, it has to do with the tilt of the Earth. The Earth's axis is not perpendicular to the plane of the ecliptic--it tilts at a 23 1/2 degree angle, and that is why we have seasons.


****.

I said tilt of the Sun, didn't I?

I'm an idiot.
timur
 
  1  
Reply Sun 22 Jun, 2014 01:21 pm
@chai2,
No, you are not.

Sun has tilt too:

Quote:
The Sun's axis tilts almost 7.5 degrees out of perpendicular to Earth's orbital plane. (The orbital plane of Earth is commonly called the ecliptic.) Therefore, as we orbit the Sun, there's one day out of the year when the Sun's North Pole tips most toward Earth. This happens at the end of the first week in September. Six months later, at the end of the first week in March, it's the Sun's South Pole that tilts maximumly towards Earth.
There are also two days during the year when the Sun's North and South Poles, as viewed from Earth, don't tip toward or away from Earth. This happens at the end of the first week in in June, and six months later, at the end of the first week of December.
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