A beautiful Moon ring

Posted on September 15, 2008. Filed under: astronomy, atmosphere, atmospheric effects, Earth, geography, ice crystals, knowledge, light, Moon, Moon halo, Moon rings, moonbow, moonlight, natural phenomenon, nature, rainbow, refraction, ring around the Moon, science, sky, stargazing, Uncategorized | Tags: , , , , , , , , , , , , , , , , , , , , |

Three nights ago, when I casually looked out of the window at the sky, I could not help exclaiming, “Wow!” It was a partly clear sky and the Moon was in its Waxing Gibbous phase. But I could observe a brilliant ring around the Moon. It formed a complete circle around the Earth’s natural satellite. On observing it carefully, I noticed that the ring was actually made of multiple colours, like a rainbow, though the seven colours were not clearly distinguishable. Sometimes it is also referred to as a moonbow. Many others in my city seem to have noticed this beautiful phenomenon as well.

A brilliant Moon ring . . .

Image: http://flickr.com/photos/spiralstares
Photographer: Spiralstares (taken with a Canon PowerShot S200 on January 19, 2005)

Since it was the first time I was observing such a ring, I searched for information about Moon rings and this is what I found:

The ring around the Moon is caused by the refraction of moonlight (which of course is reflected sunlight) from ice crystals in the upper atmosphere. The shape of the ice crystals results in a focusing of the light into a ring. Since the ice crystals typically have the same shape, namely a hexagonal shape, the Moon ring is almost always the same size. The six-sided ice crystals refract, or bend, light in the same manner that a camera lens bends light. The ring has a diameter of 22° , and sometimes, if one is lucky, it is also possible to detect a second ring with a diameter of 44°. Thin high cirrus clouds lofting at 20,000 feet or more contain tiny ice crystals that originate from the freezing of super cooled water droplets. These crystals behave like jewels refracting and reflecting in different directions.

There are some interesting beliefs about Moon rings. Folklore has it that a ring around the Moon signifies that bad weather is coming, and in many cases this may be true. So how can rings around the Moon be a predictor of weather to come? The ice crystals that cover the halo signify high altitude, thin cirrus clouds that normally precede a warm front by one or two days. Typically, a warm front will be associated with a low pressure system which is commonly referred to as a storm. Some even believe that the number of stars within a Moon ring indicate the number days before bad weather will arrive. Read more about Moon rings and other moonlight effects on this site.

Have you ever observed this natural phenomenon?

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Don’t miss these celestial fireworks!

Posted on August 7, 2008. Filed under: astronomy, atmosphere, comets, Earth, Earthlings, meteor showers, Moon, news, Perseid meteor shower, Perseids, Perseus constellation, ram pressure, random, science, shooting stars, sky, space, stargazing, Sun, Swift-Tuttle comet | Tags: , , , , , , , , , , , , , , , , , , , |

The Perseid meteor shower is expected to peak on the morning of August 12, 2008.

A Perseid streaking across the sky in St.Polycarpe, Quebec, Canada…

Image: Frederic Hore (from http://www.spaceweather.com)

Meteor showers occur when the Earth passes through the orbit of a comet. Comets leave behind dust and other particles when they pass by the Sun. When the Earth moves through the orbit of a comet, these particles enter our atmosphere at a very high speed. Since most of them are tiny particles, they vapourise completely on entering the atmosphere due to the ram pressure (pressure exerted on an object as it passes through a fluid medium – can be a liquid or a gas), leaving a trail of light that is visible from the surface of the Earth as a “shooting star”.

This particular meteor shower appears to come from the Perseus constellation and has been named as the Perseid meteor shower. The Perseids occur when our planet passes through the orbit of the Swift-Tuttle comet.

The meteor shower will be quite active from August 8 to August 14, with the peak occurring on the morning of August 12. Once the Moon sets on August 12, one should be able to watch at least a few of these shooting stars in the dark sky before sunrise. The best place would be the countryside, as far away from the city as possible.

Hopefully, the Perseids won’t disappoint Earthlings waiting to catch a glimpse of these beautiful shooting stars! 🙂

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