Thursday, January 24, 2019

Serendipitous Eclipse

It happens very seldom that the weather gives us a break exactly when we astronomical observers want one. Usually it's the reverse: the weather is reasonable just before an interesting event. Then,  just a few hours before event time the weather clouds up, or rain starts, or snow, or any other condition which prevents us from observing is going to occur.

This time, we got a lucky break. The weather cleared up just a few hours before the recent total lunar eclipse. Our granddaughters, who are also members of the RASC (as I am), took some nice pictures of the eclipse (I set up a telescope on the rear porch at home and just observed by eye, binoculars, and the telescope). I downloaded only one image from Slooh. com the remotely-accessed organization.

Here is one of Marina's pictures.

Image may contain: night



Here is my only image, taken with a remote-control telescope at Slooh.com:



I'm always fascinated by the media's statements when they are hyping a completely normal astronomical event which repeats itself often with descriptions like "Blue Moon, Harvest Moon, Wolf Moon, Super Moon", and other mystical names.

We will have no more total lunar eclipses this year. A partial lunar eclipse this year will occur on July 16. The next total lunar eclipse will occur on May 26, 2021. On November 19, 1921 will be a partial lunar eclipse. Another total lunar eclipse occurs on May 16, 2022. In between occur several penumbral lunar eclipses, on Jan 10, 2020, June 05, 2020, July 05, 2020, Nov 30, 2020 all usually almost invisible, because the brightness of the full moon varies very little. Penumbral lunar eclipses are caused by the Moon just missing the Earth's shadow.

The Moon's orbital plane differs from the Earth's orbital plane around the Sun by about 5 degrees. There are two crossover points, the ascending and descending nodes. Both solar and lunar eclipses (partial and total) can occur only when these nodes are "in line" with the Sun, and the Moon is very near, or at one of them. That also means the both types of eclipses occur at either "new Moon" (solar) or "full" Moon (lunar). These nodes slowly move around the plane of the Earth's orbit, giving rise to various series of "eclipse cycles" which repeat over hundreds of years.

You can let your imagination play by thinking about what these various types of eclipses would look like if you found yourself on the Moon...

The total lunar eclipse on January 20 was indeed serendipitous.


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