Caption: "Negative photograph of the 1919 solar eclipse taken from the report of Sir Arthur Eddington (1882--1944) on the 1919 Solar Eclipse Expedition to verify Albert Einstein's (1879--1955) prediction of the bending of light around the Sun: i.e., of gravitational lensing by the Sun." (Somewhat edited.)
Because it is a negative photograph, bright is dark and dark is bright. We are seeing near side of the Moon in its nighttime (it's the white circle) during a total solar eclipse. The sky is whitish and the solar corona is black.
To digress into thermodynamics and statistical mechanics, there are negative temperatures on the Kelvin scale: i.e., temperatures below absolute zero.
What the Devil you say. Himself is illustrated in the figure below (local link / general link: dore_satan.html).
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Recall absolute zero is the state
where all microscopic
energy
that can be removed from a system
has been removed.
Note quantum mechanics
dictates that there is an irremovable amount of energy,
the zero-point energy.
So there is a coldest: absolute zero.
Now temperature (i.e., Kelvin temperature) is fundamentally a parameter controlling the distribution of energy among the microscopic states of matter.
The negative temperature states have removable amounts of energy, but it is distributed among the microscopic states in a weird way that requires a negative temperature: i.e., a negative parameter controlling the distribution of energy among the microscopic states of matter.
So in the view of yours truly, the negative temperature states are NOT colder than absolute zero---they could be hot to the touch.
Negative temperature states are rather delicate things to create in the laboratory. They must occur in nature, but probably pretty rarely and fleetingly in most places.
Credit/Permission:
Sir Frank Watson Dyson (1868--1939),
Sir Arthur Eddington (1882--1944),
Charles Rundle Davidson
(1875--1970),
1919
(uploaded to Wikimedia Commons
by User:Fastfission,
2005) /
Public domain.
Image link: Wikimedia Commons:
File:1919 eclipse negative.jpg.
Local file: local link: 1919_solar_eclipse_negative_thermo.html.
File: Thermodynamics file:
1919_solar_eclipse_negative_thermo.html.