Last night we got the celebrate the last day of January with a "super blue blood moon". "Super", while the moon was at is closest orbital point to Earth (although with naked eye its hard to discriminate a "super" moon from a normal full moon that is only 14% smaller). "Blue" while this is the second full moon within one month. Obviously, this doesn't has anything to do with the actual colour but it's nice to know where the saying "once in a blue moon" comes from. "Blood" refers to the actual colour of the moon and can be explained with optics. In the full eclipse the Earth completely block sun light being reflected directly. The Earth's atmosphere bends some sun light that is reflected from the moon back to Earth. This light is scattered by atmospheric molecules that act as Rayleigh scatterers. In the Rayleigh scattering the short (blue) wavelengths are scattered the most and the longer (red) wavelengths are past trough most efficiently causing the blood like appearance. The same phenomenon is observed during the sun set.
Lucky for me, I was in "down under" in Australia where the "super blue blood moon" spectacle was observable at night time from cloudless sky. My nigh sky photographing skills are improving since my corona blog post although a camera stative would have been helpful allowing a longer exposure. Next time.
Comments