why is that for the two weeks after the solstice, the Sun rises later each day but sets at almost the same time?
Is it because the angle of the earth's axis changes with respect to the sun?
2007-06-21 04:25:40 · 4 answers · asked by OOGLY 4 in Science & Mathematics ➔ Astronomy & Space
One would expect the sun to rise later and set sooner in equal amounts.
2007-06-21 04:27:59 · update #1
No, it's because we are farther from the sun in summer that what we are in winter. Therefore the earth moves slower on its yearly orbit now (expressed in degrees per day) than what the orbit angular speed is in winter. Because our normal 24 hr day is a MEAN solar day, the sun is either fast or slow to this mean value. From local solar noon to local solar noon the earth has to rotate 360° plus the angle of the path of the orbit that was done between the two noons. This makes the drifting of the solar noon (and midnight) in respect to our clocks which run according the yearly mean value.
2007-06-21 04:36:35 · answer #1 · answered by Ernst S 5 · 3⤊ 0⤋
You would expect it to work like you say if the sun traced a simple line in the sky as it went north to south and back again. But the truth is, it traces a figure 8 in the sky. Sometimes the morning moves, sometimes the set time moves, sometimes they move together.
http://www.perseus.gr/Astro-Solar-Analemma.htm
Look at these cool photos. They are taken at the same time every week for year to get the dots in the sky as traced by the sun. The figure eight pattern is easy to see this way.
This pattern is caused by our orbit not being a perfect circle. It is an elipse with the sun off center at one of the focii of the elipse.
2007-06-21 06:49:58 · answer #2 · answered by Owl Eye 5 · 2⤊ 0⤋
That figure-8 that the Sun traces out is called an analemma. It is caused both by the fact that Earth's axis of rotation is tilted, and by the fact that Earth's orbit is an ellipse and not a perfect circle. A great website that explains it all using animations is http://www.analemma.com/
2007-06-21 07:15:07 · answer #3 · answered by kris 6 · 2⤊ 0⤋
I never thought of it before, but, off the top of my head, your axis-tilt theory may explain it. I presume you have witnessed what you ask about with daily precision.
2007-06-21 04:33:40 · answer #4 · answered by Anonymous · 0⤊ 0⤋