Super harvest blood moon a combination of three lunar phenomena
It was a lunar hit for a triple.
Everyone with clear skies across the Americas had a front-row seat Sunday night, September 27 to a rare total eclipse of the super-harvest moon (until the clouds moved in near the 9:48 p.m. peak time in the Mountain Lake area).
Three separate lunar events converged. The total eclipse coincided with the full moon nearest the fall equinox – or harvest moon. What’s more, the moon was at its closest approach to Earth for the year, making it also a supermoon (perigee moon). This means the moon appeared slightly large than it usually does – 13% larger (and 30% brighter). That’s why it’s called a Super Harvest Blood Moon.
This lunar trio event has happened only five times since 1900. According to NASA (National Aeronautics and Space Administration), the last celestial triple combination was in 1982 – and it won’t repeat until 2033.
As noted on http://news.nationalgeographic.com/2015/09/150924-super-total-lunar-eclipse-moon-sky-watching-viewing/, this blood moon will be the last in a series of four lunar eclipses – dubbed a tetrad – over the last two years. That pattern won’t repeat for another 20 years or so.
The most spectacular part of the eclipse was the totality phase, when Earth’s shadow completely covered the moon and turned it an eerie red. At that time, the moon dipped into the deepest and darkest part of Earth’s shadow (or umbra), which lasted approximately 72 minutes.
In a lunar eclipse, Earth casts a shadow on the moon. This doesn’t happen every time the moon makes its monthly trek around Earth, though, because the moon’s orbit is tilted, so it usually falls above or below Earth’s shadow.
Total lunar eclipses – known as blood moons – are even more rare. They happen only during a full moon – and only when the sun, Earth, and moon are precisely aligned so that Earth’s shadow completely blankets the moon’s disk. This usually happens only twice a year – and can be seen from only one hemisphere of the Earth.
During the total eclipse, sunlight shining through the ring of Earth’s dusty atmosphere is bent, or refracted, toward the red part of the spectrum and cast onto the moon’s surface.
As a result, the lunar disk went from a dark gray color during the partial phase of the eclipse to a reddish-orange color during totality.
Skywatchers across eastern North America saw all the phases of this special sky show as the moon rode high in the eastern sky, while observers in the far western parts of the continent saw the moon begin to be gobbled up by Earth’s shadow as it rises in the east, just after local sunset. Eclipse watchers in South America saw the show later in the night local time, and skygazers in Europe and most of Africa watched it during the early morning hours local time on Monday, September 28. Unfortunately, this time around, folks in Asia and Pacific Ocean were on the wrong side of the planet when the eclipse was under way.
The next total eclipse will appear on January 31, 2018 – and will be visible from western North America and the entire eastern hemisphere.
