July 22, 2019

Event of the Week: 13.07.09: Volcanic Sunsets?

 

 

Have you noticed that summer sunsets and sunrises have been a tad… scarlet as of late? This is not just your imagination… there are literally tons of volcanic dust currently aloft.  The source is mainly Sarychev Peak volcano, located in the Russian Kuril islands. Part of the Pacific Ring of Fire, Sarychev has been in the throes of eruption as of late, producing some fairly mind blowing pictures as the International Space Station orbits high overhead. One of the most active volcanoes in the world, Sarychev last erupted en-mass in 1989. The current eruption has placed a large sulfur dioxide plume circling the Earth’s northern hemisphere, causing spectacular twilight shows. Unfortunately, there are no total lunar eclipses for the remainder of the year, but sky observers should be on the watch for odd hued Moons, none the less. Near sky phenomena can be just as fascinating as distant faint fuzzies, and all you need for equipment is your eyes!

This week’s astro-word of the week is Rayleigh scattering. Ever wonder why the sky is blue? Rayleigh scattering is caused by the scattering of light waves by gases in the Earth’s atmosphere. The clearer the skies are of dust and aerosols, the lower the wavelength threshold and deeper blue the sky will be. Conversely, when the Sun or Moon are at a low angle, it must travel through more air to reach your eye. Shorter wavelengths such as blue and green get filtered out, leaving dramatic oranges and reds. Relatively large particles from volcanic eruptions such as Sarychev can effect this process for years, producing dramatic crimson twilight skies and deep-dark lunar eclipses all over the globe.

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