Lunar Halo and Jupiter
In hope of observing the Orionids Meteor Shower, I and some UP Astrosoc friends planned to go to the south to avoid the unfavorable weather in Manila. Unfortunately, we were not able to pursue the plan due to the heavy rain. Instead, we went to Naic, Cavite, a town just a few kilometers outside Manila, a day after super typhoon Megi left the country to try our luck.
We arrived at the local beach resort and started setting up our things including our tent at around 11:00 PM. The sky was totally overcast, but the waning gibbous moon and a star, which I know was the planet Jupiter, were visible then.
After a few minutes of observing the two, we noticed a faint but full 22 degree lunar halo circling the moon. Jupiter was just within the circle. We even got more amazed as the halo became clearer when the moon reached the zenith. One of us took a shot of this stunning view using her Canon 400D Digital SLR camera.
Lunar halos are caused by sunlight being refracted by cirro-stratus clouds. Cirro-stratus clouds are thin clouds, very high in the atmosphere, and are composed of ice crystals. The shape of the ice crystals results in a focusing of the light into a ring. They bend light at a 22 degree angle, which creates a solar halo or lunar halo that is 44 degrees in diameter.
Since the ice crystals typically have the same shape, namely a hexagonal shape, the Moon ring is almost always the same size. Less typical are the halos that may be produced by different angles in the crystals. They can create halos with an angle of 46 degrees.
The sky remained overcast during the rest of the evening until twilight and so we were not able to see even a single fireball.
Nevertheless the attempt was worth a try, thanks to that wonderful halo which left us amazed and happy. 😀