Beauty of sky

Total solar eclipse, 21.08.2017, Riverton, WY (United States)

Lunar shadow movement

When close to the totality, is easy to spot a shadow moving fast across the sky. The speed of the lunar shadow depends on a few factors, where the most important is solar altitude above the horizon. Due to this the umbral speed can vary from around 600m/s even to 55km/s (Macdonald, 2011). This enormous speed is to be seen especially on the sky and high-level clouds just before and after the totality. The sky colour and lunar shadow appearance changes significantly every second, especially when crossing the zenith sky. Sometimes this phenomenon is also possible to see on remote mountains in some rough areas.

Lunar shadow position at 2nd contact (credits: Piotr Dzikowski).
Lunar shadow position at the mid-eclipse (credits: Piotr Dzikowski).
Lunar shadow position at 3rd contact (credits: Piotr Dzikowski).

An umbral edge marked on the sky at the moment of 3rdcontact.
Solar prominences as seen after totality at over 97% obscuration, ISO 100, 1/4000s, f/5.6.

I have made a shadow-in and shado-out sequences, from my coleague footages as follows:

Shadow-in sky towards north (credits: Piotr Chabior).

Shadow-in sky towards WNW (credits: Tomasz Rac).

Shadow-out sky towards ESE (credits: Piotr Chabior).

Shadow-out sky towards ESE (credits: Tomasz Rac).

Short period before and after totality on WNW (shadow-in) and ESE (shadow-out) section of sky - comparison (credits: Tomasz Rac).
Shadow-in and shadow-out sky comparison during totality (credits: Tomasz Rac)

Lunar shadow was looking intruguingly just before the 2nd contact.

Lunar shadow position on the shadow-in sky at 30s before totality.
Lunar shadow position on the shadow-in sky at 30s before totality - saturated.
Lunar shadow position on the shadow-in sky at 30s before totality - modified

Lunar shadow position on the shadow-in sky at 30s before totality - explained.
Lunar shadow position on the shadow-in sky at 30s before totality with view towards Owl Creek Mts.
Lunar shadow position on the shadow-in sky at 30s before totality with view towards Owl Creek Mts - saturated.

Lunar shadow position on the shadow-in sky at 30s before totality with view towards Owl Creek Mts - explained.
Lunar shadow position on the shadow-in sky at 30s before totality - view towards W to NW direction (2 simple shots with amazing difference).
Lunar shadow position on the shadow-in sky at 30s before totality - view towards W to NW direction (2 simple shots with amazing difference) - saturated.

Lunar shadow position on the shadow-in sky at 30s before totality - view towards W to NW direction (2 simple shots with amazing difference) - explanation: 1 - shadow seen on clouds, 2 - shadow seen on haze (planetary boundary layer), 3 - shadow seen on the sky (likewise civil wedge).

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