Astronomy Picture of the Day - 2017 July 5 - Aphelion Sunrise
Astronomy Picture of the Day
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.
Image Credit &Copyright: Stephen Mudge
Explanation
On July 3rd,planet Earth reached aphelion, the farthest point in its elliptical orbit around the Sun.
Each year, this day of the most distant Sun happens to occur during winter in the southern hemisphere. That's where this aphelion sunrise from 2015 was captured in a time series composite against the skyline of Brisbane, Australia. Of course, seasons for our fair planet are not determined by distance to the Sun, but by the tilt of Earth's rotational axis with respect to the ecliptic, the plane of its orbit.
Fondly known as the obliquity of the ecliptic, the angle of the tilt is about 23.4 degrees from perpendicular to the orbital plane. So the most distant sunrise occurs during northern summer, when the planet's north pole is tilted toward the Sun and the north enjoys longer, warmer days.
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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
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