Rotation

With a time lapse video in the winter and in the summer, I could cover the whole northern sky: When it’s getting bright in one of the videos, it starts to get dark in the other one. Probably best to watch fullscreen:

Winter night sky time lapse. For full screen: https://youtu.be/SqYlLvelal8 (unfortunately, dew on the lens made the stars less visible)
Summer night sky time lapse. For full screen: https://youtu.be/qDIjs-YaC5Q

The reason behind is between the two videos, the earth has done half a round around the sun and so at midnight, when looking at Polaris, one looks from opposite directions.

Moon halo (22° halo)

The moons 22° halo, as seen in a March night. This photo was taken by Ronny Errmann in his garden.
The moons 22° halo, as seen in a March night.

Recently I was made aware about an impressive moon halo, also know as moon dog. I have seen light versions of it before, but not as clear.

It happens when a layer of ice crystals forms high in the atmosphere. Each of the crystals then acts as a prism, refracting the light into a certain way. It’s a similar (and yet not) effect like when a rainbow forms. And actually a moon halo also has a colour gradient, the inner bit is red, the outer bit is blue. However, in my image that is not visible, a longer exposure time would have been good. Next time 🙂

Instead, what I did was recording a time lapse for 30 minutes:

30 Minute time lapse of a moon halo

While some clouds move very quickly, the only apparent change of the halo is caused by earth’s rotation (the moon and halo moving along the image). This also made clear, what are stars and what are optical effects/defects from the lens. Right to the moon are Castor and Pollux of constellation Gemini, and below the moon, next to the tree, is Procyon. All stars fainter than magnitude 2 are invisible due to the scattered moon light (which itself is just reflected sun light).

More information can be found on the Wikipedia article about moon halos: https://en.wikipedia.org/wiki/22%C2%B0_halo

Two and a half years earlier a got a glimpse of a sun halo:

Shitty sun halo (see small area below)
Shitty sun halo (see small area below)
Sun halo, seen from a moving train, which is just not ideal
Sun halo, seen from a moving train, which is just not ideal

Nicer examples of sun halos can be found on Wikipedia: https://en.wikipedia.org/wiki/Halo_(optical_phenomenon)

Create a time lapse from individual images: https://ronnyerrmann.wordpress.com/2022/02/12/commands-to-create-time-lapse-videos-from-individual-frames/