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The Comet C/2020 F3 (also known as "NEOWISE") appears to move compared to stars in the background:
(Screenshots from Stellarium)

enter image description here

enter image description here

Those images are one hour apart as seen from Germany.

Is this parallax primarily caused by the motion of earth or by the comet's motion? We know that Earth is moving at around $30 \frac {km}{s}$ around the sun and C/2020 F3 has a speed of about $77.6 \frac {km}{s}$.

I assume that the parallax is a combination of the movement of both objects, but given the distance between earth and the sun (~149 million km) and the distance between the earth and C/2020 F3 (~103 million km at its closest approach) as well as the distance between the comet and the sun (~43 million km at its closest approach), can we determine whether the motion of one of the objects is (a lot) more dominant in causing the parallax?

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The parallax of the Sun is 1 degree per day. The distance of comet Neowise from Earth is currently 0,7 AU, so its parallax is 1.4 degree per day. The comet's apparent motion is about 3 degrees per day, so its parallax is about half of that.

In Stellarium it is possible to look below the horizon, and see the motion of the Sun. It should resemble this:

enter image description here Red: my comet observations; Green: parallax of the Sun. © star map: Dominic Ford

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