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Credit & Copyright: Giuseppe Petricca
Explanation:
If you went outside at the same time every day and
took a picture that included
the Sun, how would the Sun's position change?
A 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 noon 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 and 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.
The featured image was taken near the December solstice and so the Sun appears near the bottom.
Equinoxes, however,
correspond to analemma middle points -- not the
intersection point.
In two days there will be an
equinox ("equal night"),
when day and night are equal over all of planet Earth.
Many
cultures celebrate a change of season at an
equinox.
APOD's main NASA site is
moving:
From apod.nasa.gov to
science.nasa.gov/apod
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: equinox
Publications with words: equinox
See also:
- APOD: 2026 March 20 Á Spring Equinox at Teide Observatory
- APOD: 2026 March 15 Á Equinox at the Pyramid of the Feathered Serpent
- APOD: 2025 September 22 Á Equinox at Saturn
- APOD: 2025 September 21 Á Equinox Sunset
- APOD: 2024 September 22 Á Chicagohenge: Equinox in an Aligned City
- Sunrise Shadows in the Sky
- APOD: 2024 March 19 Á A Picturesque Equinox Sunset