Comet NEOWISE Was Spiraling and Spinning as it Passed by Earth

Earlier this week, we shared an image of Comet NEOWISE (C/2020 F3) taken by the Hubble Space Telescope. And now, here are a group of images from the 8.1-metre Gemini North telescope in Hawaii. Like Hubble, Gemini North focused in on the comet’s nucleus and coma, instead of its stunning, gossamer tails. But Gemini zoomed in and caught something Hubble didn’t: Comet NEOWISE was rotating, which created a spiraling stream of molecular gas.

The close-up observations, led by Michal Drahus and Piotr Guzik of Jagiellonian University in Krakow, who were looking to try and see and study the rotational dynamics of the comet. Despite limitations imposed by the comet’s proximity to the Sun, the researchers were able to confirm a 7.5-hour rotation period by measuring the spiral outflow of molecular gas as NEOWISE spun about.

The rotation of Comet NEOWISE is revealed in eight images captured over one-and-a-half hours on 1 August by the Gemini North telescope using the Gemini Multi-Object Spectrograph. In the compressed time-lapse sequence below, the images are looped nine times. Image: International Gemini Observatory/NOIRLab/NSF/AURA/M. Drahus/P. Guzik

Here’s a timelapse video created by all the images taken by the team at Gemini North:

The prevailing notion is that most comets “release gasses in geyser-like jets and that is what researchers think is happening in the Gemini images,” the National Science Foundation’s NOIRLab said in a description. NOIRLab is US national center for ground-based, nighttime optical and infrared astronomy. “As the vaporized material erupts from the comet its rotation causes it to appear to spiral outward, much like the water from a spinning garden hose. The very same material impacts the comet’s rotation causing its nucleus to spin-up or spin-down, though for most comets, the effect is too weak to detect.”

In another set of impressive ground-based observations, an amateur astrophotographer from Germany, Bernd Gährken, was also able to capture some of the rotation as well.

Spiral rotation of Comet NEOWISE (C/2020 F3) as seen on July 26, with a with an 80cm f/10 Cassegrain at the Bavarian Public Observatory in Munich, Germany. On the right,Gährken has highlighted the spirals in the comet’s rotation. Credit and copyright: Bernd Gährken.

Gährken was able to see the details of the spiral rotation, and he created a gif animation:

An animation of Comet NEOWISE (C2020 F3) was created from 4 pictures, approximately 6 minutes apart, each (total time lapsed is 25 minutes) from July 29, 2020. Images taken with an 80cm f/10 Cassegrain at the Bavarian Public Observatory in Munich, Germany. Credit and copyright: Bernd Gährken.

You can see more of his Comet NEOWISE images at his website.

Astronomers will certainly be studying Comet NEOWISE’s fascinating pass by our planet for quite some time!

Hat tip to Daniel Fischer (cosmos4u) on Twitter