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In which way do the Earth's rotational axis tilted 23.5°.

enter image description here

see in the image we have been told that the axis of rotation of Earth is tilted 23.5° from the perpendicular to path. But can anyone say in which direction the earth is tilted .AO or BO. Is the axis of rotation tilted towards sun or away from sun. And still it is confusing in solstices. Where the rotation axis of Earth at one solstice is towards the sun and at other solstice away from sun.

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    $\begingroup$ Have you not seen something like en.wikipedia.org/wiki/Axial_tilt#/media/… ? $\endgroup$ – Eric Towers Nov 2 '20 at 20:31
  • $\begingroup$ @EricTowers Thanks. There is also written that "tilt is constant relative to some fixed stars" but not specified. $\endgroup$ – Debakant Nov 3 '20 at 2:57
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It's tilted with the N pole toward the sun at Summer Solstice, and S pole toward the sun at Winter Solstice (assuming you are in the northern hemisphere, and winter is in December).

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The tilt is always 23.5 degrees, and it always points in the same direction (roughly to the Polaris star), but that means that it does not always point towards the sun or away from it. That depends on the time of year.

Let's say that in your drawing Polaris is "above" the earth orbit, and "left" from the center. Then the earth axis is tilt "to the left", matching your A direction.

At the "right" end of the orbit (as seen in your drawing), the axis points towards the sun, and that corresponds to June, meaning lots of sun (= summer) for the northern hemisphere.

Half a year later, in December, the earth is at the "left" end of its orbit (invisible part of your drawing), its axis still pointing to the left, which now means "away from the sun", resulting in less sunlight (= winter) for the northern hemisphere.

So, to literally answer your question:

Both A and B are correct, with A matching in June, and B matching in December (and looking into the solar system from the opposite direction).

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  • $\begingroup$ Appreciated.... basically the "Polaris star" helped a lot. $\endgroup$ – Debakant Nov 2 '20 at 15:44
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    $\begingroup$ Technically, the axis precesses over a long time period, so Polaris will not always be the north star... $\endgroup$ – Lawnmower Man Nov 2 '20 at 18:26
  • $\begingroup$ @LawnmowerMan btw it helps to visualize current position. When it will change I will change my visualisation. No problem 😊. $\endgroup$ – Debakant Nov 3 '20 at 2:44
  • $\begingroup$ I hope you live long enough to be able to update the drawing, when the axis no longer points to Polaris (meaning a significant portion of 25772 years). $\endgroup$ – Ralf Kleberhoff Nov 3 '20 at 9:05
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The angle of tilt is measured between the axis of rotation and a line which is perpendicular to the plane of the orbit. The direction of tilt relative to the “fixed” stars changes very slowly (over thousands of years); a precession caused by a variable torque primarily from the moon. (It pulls harder on the closer side of the equatorial bulge.

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    $\begingroup$ I asked which side relative to anything the tilt angle is measured around the axis perpendicular to the path not whether it changes or not $\endgroup$ – Debakant Nov 2 '20 at 15:40
  • $\begingroup$ @Debakant that's like asking which way a spinning ice skater is pointing. $\endgroup$ – Lawnmower Man Nov 2 '20 at 18:27

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