This is the beautiful comet C/2021 A1 Leonard after its closest approach to the Sun:

The coma is greenish and the tail is reddish. The tail became very long as it approached the Sun – up to about 60 degrees long!

This is what the comet looked like on December 30, 2021 – a few days before its closest approach to the Sun:

The tail here is showing a disconnection event caused by the solar wind.

These images were processed using PixInsight. As an experiment, I processed the same data from the second image using DSS and Photopea.com, and this is the result:

The difference between the two images is dramatic: there’s much less detail in the DSS-processed image. It also took a long time to process using DSS and I had to perform a number of adjustments in both DSS and Photopea.com to get the resulting image.