The Shifting Tails of Comet NEOWISE
Image Credit & Copyright:
Ignacio Llorens
Keep your eye on the ion tail of Comet NEOWISE.
A tale of this tail is the trail of
the Earth.
As with all comets, the
blue ion tail always points away from
the Sun.
But as Comet C/2020 F3 (NEOWISE)
rounded our Sun, its ion tail pointed in slightly different directions.
This is because between 2020
July 17 and
July 25 when the featured images were taken,
the Earth moved noticeably in its orbit around the Sun.
But the Earth's motion made the Sun appear to shift in the sky.
So even though you can't see the Sun directly in the featured image(s),
the directions of the ion tails
reveal this apparent solar shift.
The Sun's apparent motion is in the
ecliptic,
the common plane where all planets orbit.
The featured five image composite was meticulously
composed to accurately place each comet image --
and the five extrapolated solar positions -- on a single foreground image of
Turó de l'Home Mountain,
north of Barcelona,
Spain
Comet NEOWISE is no longer the
impressive
naked-eye
object it was last month,
but it can
still be found
with a small telescope as it heads back to the outer Solar System.