Explanation:
Why does Comet Leonard's tail wag?
The featured time-lapse video shows the ion tail of
Comet C/2021 A1 (Leonard) as it changed
over ten days early last month.
The video was taken by NASA's
Solar Terrestrial Relations Observatory-Ahead (STEREO-A)
spacecraft that
co-orbits the Sun at roughly the same distance as the Earth.
Each image in this 29-degree field was subtracted from
following image to create frames that highlight differences.
The video clearly shows Comet Leonard's long ion tail extending,
wagging, and otherwise being
blown around by the
solar
wind -- a stream of fast-moving
ions that stream out from the
Sun.
Since the video was taken,
Comet Leonard continued plunging toward the Sun, reached its
closest
approach
to the Sun between the orbits of Mercury and Venus,
survived this closest approach without
breaking apart,
and is now fading as heads out of our
Solar System.
Tuesday over Zoom: APOD editor to present the
Best APOD Space Images of 2021
