Udupi: Treat Awaits Skygazers - Total Lunar Eclipse on Dec 10

Udupi, Dec 9: One of the best sky events of this year will be the lunar eclipse on Saturday  December 10, when the full moon passes deep into Earth shadow. The total eclipse will occur between 7.36 pm to 8.27 pm for 51 minutes. The eclipse will start at 6.15 pm and end at 9.52 pm

A lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur on the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes. Unlike a solar eclipse, which can only be viewed from a certain relatively small areas of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at any given place, due to the smaller size of the moon's shadow

The shadow of the Earth can be divided into two distinctive parts: the umbra and penumbra. Within the umbra, there is no direct solar radiation. However, as a result of the Sun’s large angular size, solar illumination is only partially blocked in the outer portion of the Earth’s shadow, which is given the name penumbra. A penumbral eclipse occurs when the Moon passes through the Earth’s penumbra. The penumbra causes a subtle darkening of the Moon's surface. A special type of penumbral eclipse is a total penumbral eclipse, during which the Moon lies exclusively within the Earth’s penumbra. Total penumbral eclipses are rare, and when these occur, that portion of the Moon which is closest to the umbra can appear somewhat darker than the rest of the Moon.
A partial lunar eclipse occurs when only a portion of the Moon enters the umbra. When the Moon travels completely into the Earth’s umbra, one observes a total lunar eclipse. The Moon’s speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the Moon’s first and last contact with the shadow is much longer, and could last up to 4 hours. The relative distance of the Moon from the Earth at the time of an eclipse can affect the eclipse’s duration. In particular, when the Moon is near its apogee, the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease appreciably within the changes in the orbital distance of the moon. Thus, a totally eclipsed Moon occurring near apogee will lengthen the duration of totality.
The Moon does not completely disappear as it passes through the umbra because of the refraction of sunlight by the Earth’s atmosphere into the shadow cone; if the Earth had no atmosphere, the Moon would be completely dark during an eclipse. The red coloring arises because sunlight reaching the Moon must pass through a long and dense layer of the Earth’s atmosphere, where it is scattered. Shorter wavelengths are more likely to be scattered by the air molecules and the small particles, and so by the time the light has passed through the atmosphere, the longer wavelengths dominate. This resulting light we perceive as red. This is the same effect that causes sunsets and sunrises to turn the sky a reddish color; an alternative way of considering the problem is to realize that, as viewed from the Moon, the Sun would appear to be setting (or rising) behind the Earth.
The amount of refracted light depends on the amount of dust or clouds in the atmosphere; this also controls how much light is scattered. In general, the dustier the atmosphere, the more that other wavelengths of light will be removed (compared to red light), leaving the resulting light a deeper red color. This causes the resulting coppery-red hue of the Moon to vary from one eclipse to the next. Volcanoes are notable for expelling large quantities of dust into the atmosphere, and a large eruption shortly before an eclipse can have a large effect on the resulting color.

The moon likely will take on an orange red colour during totality as a small amount of sun light passes through earth atmosphere and scatters on to our only natural planet at totality.

A beginner’s guide to the lunar eclipse

 
This June 15 we all have a date with the moon.
A blushing moon that hides behind the earth’s veil is an all too familiar tale we have all heard.
For most, childhood is far behind and confusion abound. Does the sky burn bright or is it a diamond ring in the sky, are amidst so many questions that heckle the mind.
To begin with, let’s dissolve those illusions and delusions – there are no werewolves, and if you’re pregnant, your kid won’t be born with missing toes and oddly-shaped marks. So all those mommas feel free to shuffle around!
In an attempt to vanquish demon superstitions – here’s what those 160-something IQ-ed science geeks have to say:
First, you cannot have a lunar eclipse without a full moon at night, and unlike its alter ego – the solar eclipse, you can view the event from several spots on earth. So, if you’re planning to travel, make sure you hit Africa, Central Asia, South America, Europe, Australia or the Philippines – or just sit back at home in India.
Lucky for us, we will be witnessing what is called a total lunar eclipse. A total eclipse sees an inflamed moon, crimson-hued in the darkest of skies eclipses could have. For those who value their sleep, the eclipse lasts for almost three and a half hours. The eclipse shall commence with a dimming disappearance of the moon, also called the partial phase.
When it’s time, the moon shall shy away behind the triumphant shadow of the earth. Blocking out the light of the sun, the moon will slowly be eschewed till it reappears with its fiery facet during the total phase. Playing hide and seek once again, the body disappears to resurface in its placid tone of grey thereby ending the eclipse.
Perplexities often arise on understanding how the moon changes its colour when the sun is blocked out. It is merely a reflection of the earth from the residue rays of the sun that filter through. The ash and dust in the atmosphere determine the shade that the moon would be adorning. Experts are excited this year, as they are hoping to see what effect the ash cloud over Europe would have on the eclipse.
For those who wish to capture the moment, your can take a long look with your bare eyes. Unlike solar eclipses, you wouldn’t need those shades! And for them clickers, you needn’t protect your camera with filters – the same logic works here.
So fuel-up with some Red Bull and keep those shutters ready. Total lunar eclipses can be quite a sight, quite a rare one in fact.
So, from 11:52pm to 3:30am, don’t forget to eat your way through superstition, and celebrate the moon in full bloom.