Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our
fascinating universe is featured, along with a brief explanation
written by a professional astronomer.
2020 September 22
Equinox in the Sky
Image Credit & Copyright: Luca Vanzella
Explanation: Does the Sun set in the same direction every day? No, the
direction of sunset depends on the time of the year. Although the Sun
always sets approximately toward the west, on an equinox like today the
Sun sets directly toward the west. After today's September equinox, the
Sun will set increasingly toward the southwest, reaching its maximum
displacement at the December solstice. Before today's September
equinox, the Sun had set toward the northwest, reaching its maximum
displacement at the June solstice. The featured time-lapse image shows
seven bands of the Sun setting one day each month from 2019 December
through 2020 June. These image sequences were taken from Alberta,
Canada -- well north of the Earth's equator -- and feature the city of
Edmonton in the foreground. The middle band shows the Sun setting
during the last equinox -- in March. From this location, the Sun will
set along this same equinox band again today.
Tomorrow's picture: open space
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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
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