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Credit & Copyright: Giuseppe Petricca
Explanation:
Does the Sun return to the same spot on the sky every day at the same time?
No.
A more visual answer to that question is an
analemma,
a composite image taken from the same spot at the
same time over the course of a year.
The featured analemma was composed from images taken every few days at 4 pm near
the village of
Callanish in the
Outer Hebrides in
Scotland,
UK.
In the foreground are the
Callanish Stones, a stone circle built around 2700 BC during humanity's
Bronze Age.
It is not known if the placement of the
Callanish Stones has or had astronomical significance.
The ultimate causes for the
figure-8 shape of this an all analemmas are the
tilt of the Earth axis
and the
ellipticity of the
Earth's orbit
around the
Sun.
At the solstices,
the Sun will appear at the top or bottom of an analemma.
Equinoxes, however,
correspond to analemma middle points -- not the intersection point.
Today at 1:54 am
(UT)
is the
equinox ("equal night"),
when day and night are equal over all of planet Earth.
Many
cultures celebrate a change of season at an
equinox.
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day