Who will see a selenelion – the eclipsed moon and sun in the sky simultaneously – for the April 4, 2015 total eclipse of the moon? Charts and info here.
This photo does not show an eclipsed moon, but it does show a simultaneous sunset and (nearly) full moonrise as captured byEarthSky Facebook friend Andy Somers in Noumea, New Caledonia in September 2013. On Saturday, April 4, 2015 – from just the right spot on Earth – you might see something like this … but the moon will be in eclipse!
In case you haven’t heard, there’s a total lunar eclipse coming up this Saturday, April 4, 2015. North Americans will see the eclipse Saturday morning. Australians and Asians will see it Saturday evening.Read more about the April 4 eclipse here.
If you’re in just the right spot on Earth, you might observe the eclipsed moon setting while the sun rises – or the eclipsed moon rising while the sun sets. This is called a selenelion. Celestial geometry says this should not happen. After all, in order for an eclipse to take place, the sun and moon must be exactly 180 degrees apart in the sky, in a perfect alignment known as a syzygy. Such perfection – needed for an eclipse to take place – would seem to make it impossible to view the sun and eclipsed moon above your horizon simultaneously.
But – thanks to atmospheric refraction, the same effect that causes a spoon in a glass of water to appear broken in two – you might actually see images of the sun and totally eclipsed moon, both above your horizon at once, lifted up by the effect of refraction.
You need to be positioned in just the right spot on Earth’s surface to see a selenelion.
Source::::: http://www.earthskynews.org
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