Huge Comet C/2021 A1 Leonard, solar wind disturbance seen from STEREO-A

[Holger Isenberg]

This highly enhanced view of Comet C/2021 A1 Leonard's tail structures in the solar wind extends not only visually from the Venus orbit to Earth's orbit, they are actually extending almost that far spatially as Leonard is only a few tens of million km away from Venus around December 17 and the tail is either following the Sun-Comet connection line or is bend along the Parker spiral slightly clockwise when seen from North.

Enhanced animated view from the HI2 camera on STEREO A, following 33 degree behind Earth on its orbit:
https://twitter.com/SungrazerComets/sta ... 3090157571

I tried a 3d visualization with the Celestia software and a hand-crafted description file for the comet with the position of STEREO-A estimated manually:

Comet_Leonard_20211217.jpg

https://areo.info/postfiles/Comet_Leonard_20211217.jpg

Please note that the tail in my visualization is not the tail optically visible from Earth, but my approximation of the highly enhanced solar wind disturbance shown in the animated view above.

The optically visible tail on Earth in long exposure photographs is also impressive with 35°, but it's smaller than the structure shown in the visualization and animation. Here a long term exposure from Earth: https://twitter.com/JanHattenbach/statu ... 7278368773

[Cargo]

Very Interesting! Thank you.

I would like to know more about the other objects in the image. There's a lot going on here every 4hr frame or so.

[Holger Isenberg]

In the Stereo-A animation Venus is the bright spot within the left vertical bar and Earth is the bright fuzzy two-lobe spot in the right vertical bar. That triangle is just some reflection inside the optic.

To avoid misinterpretation of my 3d visualization: That tail-like cloud in my visualization is more the extend of the solar wind disturbance as visible in the Stereo-A animation. My guess about the Stereo-A animation is some effect like Thomson Scattering of light on the electrons and protons disturbed in the solar wind by the comet. Similar to the streaks visible around the Sun in various coronagraph photos.

[JP Michael]

And i still havent had a clear evening to get my telescope out and watch it