Monday, 18 January 2010


It was a spectacular sight last night. Shortly after sunset a thin crescent moon was visible with the dark side illuminated by earthshine, i.e., sunlight reflected off the earth onto the moon and back again. Just a few degrees away was Jupiter. There was little time to think about how to take the photographs correctly so just snapped away and hoped I'd get something.

This is something you can only see for a few hours each month. It has to be close to a new moon to see earthshine and the new moon won't do it since it'll rise and set with the sun. During the day the sky is too bright to see the dimly lit dark side of the moon but for an hour or two after sunset (or just before sunrise - it depends whether the moon is waxing or waning) the moon looks very different.

You need a clear sky as well of course!


kahuku said...

I got to see this, or something near it on Sunday from Ocean View. They sky was beautiful. I guess that was Jupiter, but wasn't sure. Hope you are doing well.

Devany said...

We saw it too. I never knew what it was called! Thanks Tom.

Tom said...

Kahuku - I was hoping to see a similar sight the next evening and take a better photo but unfortunately the clouds came in!

Devany - the actual phenomenon is called planetshine (where sunlight reflected off a planet gets reflected off another). It's been seen elsewhere in the solar system (Jupiter and Saturn moons for instance) and NASA are planning to use the effect to try and detect possible life-sustaining earth-like planets around other stars!


Zuzana said...

I recall seeing something similar last winter, but the moon was lying directly under a bright shinning star, that I believe was Venus at that time, I am not sure though.
I saw the moon briefly yesterday night when the sky was clear for a few minutes, it looked similar to yours.
Great shots indeed.