Annular Solar Eclipse

Feb. 27, 2017: 12:10 p.m. to 5:36 p.m. UTC

Annular Solar Eclipse

Annular Solar Eclipse

Ever heard of an annular solar eclipse? The 'annulus' - which is latin for ring - can be clearly seen in the amazing picture behind the countdown, named 'Lord of the Rings' by astrophotographer Daniel Lynch.

Annular solar eclipses occur due to a variety in distance between the Earth-Moon and Earth-Sun systems. Why do distances between the Earth vs. the Moon and the Sun vs. the Earth change? Their orbits - when looking at it from 'above'- are simply not a perfect circle, but elliptic. Imagine a circle that is pulled from one end. The shape that now develops is elliptic. The visible ring occurs when the Moon vs. Earth distance is large - the Moon will look small and/or the Sun vs. Earth distance is small; the Sun will look large. In the image on the right you see the difference in size, referred as visual diameter. The Sun ranges from 31.6' till 32.7', while the Moon exhibits a slightly larger variation; 29.43' - 33.5'. The result of this variation is that you are able to enjoy total solar eclipses, partial solar eclipses, hybrid solar eclipses and for now an annular solar eclipse.

O yes, one thing. Maybe you were thinking, I have seen a larger than usual Moon before... You could notice the difference in visual diameter explained above, probably only if you have superman eyes. The Moon can look larger than normal, mostly when it is low at the horizon. A different explanation is the reason for this phenomenon. Any idea?

This annular solar eclipse starts february 27th at 12.10.48 Universal Time (UT). Unfortunately much of this eclipse runs over sea, starting in the Pacific and hitting land (Chili) around 13.35 UT. The actual 'ring' can be seen in a 30.6km wide path running through Chili, Argentina in South America. After crossing the Atlantic, it reaches Angola, followed by north of Zambia and the south of Congo. Although these locations are low-dense populated and thus probably not many broadcasters are expected to give you a few of this spectacular ring, about 60% of South America will be able to see a partially blocked solar disk. In Buenos Aires around 65% is being blocked, while people in Rio will have to miss 43% of the solar disk during maximum eclipse. Greatest eclipse is over the Atlantic, timed at 14.53.25 UT. Finally at 17.36.02 UT, it is over.

Author: Sander Klieverik
Main image: copyright Daniel Lynch
Map image; copyright Fred Espenak - NASA's GSFC
Supporting image: Wikipedia.

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