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.

2024 December 8
A picture of Saturn is shown with tan clouds and light
rings. Surrounding the north pole at the top are bright
blue swirls.
Please see the explanation for more detailed information.

Aurora around Saturn's North Pole
Image Credit: NASA, ESA, Hubble, OPAL Program, J. DePasquale (STScI), L. Lamy (Obs. Paris)

Explanation: Are Saturn's auroras like Earth's? To help answer this question, the Hubble Space Telescope and the Cassini spacecraft monitored Saturn's North Pole simultaneously during Cassini's final orbits around the gas giant in September 2017. During this time, Saturn's tilt caused its North Pole to be clearly visible from Earth. The featured image is a composite of ultraviolet images of auroras and optical images of Saturn's clouds and rings, all taken by Hubble. Like on Earth, Saturn's northern auroras can make total or partial rings around the pole. Unlike on Earth, however, Saturn's auroras are frequently spirals -- and more likely to peak in brightness just before midnight and dawn. In contrast to Jupiter's auroras, Saturn's auroras appear better related to connecting Saturn's internal magnetic field to the nearby, variable, solar wind. Saturn's southern auroras were similarly imaged back in 2004 when the planet's South Pole was clearly visible to Earth.

Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)
Tomorrow's picture: how many sisters?


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