Explanation:
Unusual shadows and dark rings appeared around Saturn near its equinox last month.
At that time -- early August --
Saturn's ring plane
pointed directly at the Sun.
Visible above,
Saturn's moon
Tethys casts a shadow visible only on the far right.
Saturn's own shadow
blacks out a large swath of rings on the right.
The night side of Saturn glows with
ringshine -- sunlight reflected by ring particles back onto Saturn.
Images near equinox at Saturn
are giving astronomers a
chance to search for unexpected shadows that may illuminate
previously unknown features of Saturn's complex
ring system.
Cassini,
the robotic spacecraft orbiting
Saturn that took
this image,
is not expected to survive to the next
Saturnian equinox
in 15 years.
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