SkyEye

Eclipses

Solar Eclipses

A solar eclipse occurs when the new Moon passes between the Sun and the Earth, casting a shadow on the Earth. There are three types of solar eclipses: annular, partial, and total.

A partial solar eclipse occurs when the Sun and the Moon are not quite lined up. In this case, the Moon covers only a section of the Sun. This kind of eclipse usually goes unnoticed by most people on Earth because the sunlight is scarcely dimmed.

A total solar eclipse, however, is much more spectacular. At totality, the disc of the Sun is completely obscured by the new Moon, and only the ghostly solar corona and perhaps gigantic solar flares are visible around the edges of the Moon. Those parts of the Earth experiencing totality become very dark and it is possible to see stars in the sky.

An annular solar eclipse is similar to a total eclipse except that the new Moon is near apogee and its disc appears slightly smaller than that of the Sun. Thus, a bright ring or annulus of the solar disc remains at maximum eclipse, and the sky does not become dark.

There are at least two and sometimes as many as five solar eclipses every year. Why don't we have a solar eclipse during every new Moon? This is because the Moon's orbit around the Earth is at an angle to the ecliptic. The new Moon usually passes above or below the Sun as seen from the Earth and thus there is no eclipse. The proper alignment for a solar eclipse occurs only a few times a year.

Lunar Eclipses

Another kind of eclipse is a lunar eclipse which occurs when the Moon passes through the shadow cast by the Earth. A lunar eclipse only occurs when the Moon is full and for the same reasons given above, happens only two or three times a year.

A lunar eclipse may be total, partial or penumbral. A total lunar eclipse causes the full Moon to slowly darken as it enters the umbra of the Earth and at totality, the Moon may take on a dark coppery colour. During a partial lunar eclipse, the Moon does not fully enter the umbra of the Earth. A penumbral lunar eclipse is likely to go unnoticed as the Moon passes through the Earth's penumbra and does not dim a great deal.

Observing Eclipses

You risk permanent damage to your eyes if you look at the Sun directly or through a camera viewfinder or through any kind of magnifying lens (for instance, binoculars or a telescope) unless you use proper solar filters. The safest way to observe a solar eclipse is to use a projection technique such as that employed by a pinhole camera.

If you wish to use binoculars, a camera or a telescope, then you must use a solar filter. Be sure that it is fitted on the Sun-side of the lens, not the eye-side. Cheap eyepiece filters such as those sold with inexpensive telescopes should never be used. Solar filters can be bought from camera and telescope dealers. Retinal damage can happen in seconds and cannot be repaired, so don't take chances.

Only the total phase of a solar eclipse can be viewed safely without filters.

The Moon is much less bright than the Sun so it is perfectly safe to observe a lunar eclipse without special protective equipment.

Eclipses in the Year 2012

Annular Solar Eclipse : 20-21 May
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Annular Eclipse Visibility:	Southern China, southern Japan (including Tokyo), northern Pacific Ocean, western United States (including Oregon, California, Nevada, Utah, Arizona, Colorado, New Mexico and Texas).
Partial Eclipse Visibility:	East Asia, the Pacific Ocean, the United States, Canada, Mexico, most of the Arctic and Greenland.

20:56 UT \| 20 May	The partial eclipse begins.
22:06 UT \| 20 May	The annular eclipse begins.
23:47 UT \| 20 May	New Moon.
23:54 UT \| 20 May	Instant of greatest eclipse: magnitude = 0.94.
01:39 UT \| 21 May	The annular eclipse ends.
02:49 UT \| 21 May	The partial eclipse ends.
Partial Lunar Eclipse : 4 June
Complete eclipse visible:	The Pacific Ocean, New Zealand, eastern Australia.
Moon eclipsed at moonrise:	East Asia, western Australia.
Moon eclipsed at moonset:	Most of the Americas (except easternmost parts).

08:48 UT	The penumbral eclipse begins.
09:59 UT	The partial eclipse begins.
11:03 UT	Instance of greatest eclipse: umbral magnitude = 0.37
11:12 UT	Full Moon.
12:06 UT	The partial eclipse ends.
13:18 UT	The penumbral eclipse ends.
Transit of Venus : 5-6 June
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Venus will cut across the northern limb of the Sun. This is an extremely rare event. Only seven such transits have been observed since the invention of the telescope in the early seventeenth century: 1631, 1639, 1761, 1769, 1874, 1882 and 2004. The next two transits will not occur until 2117 and 2125.
It is just about possible to observe this event without optical magnification but the view is much better with large binoculars or a small telescope. Any such device must be equipped with the same high-quality solar filters that you would use for observing a solar eclipse. Make sure that the transit of Venus is not the last thing you see.
Complete transit visible:	Eastern Australia, eastern Asia, New Zealand, western Pacific Ocean, the Arctic.
Transit in progress at sunrise:	Western Australia, western Asia, India, the Middle East, eastern Africa, most of Europe (except Spain and Portugal).
Transit in progress at sunset:	North America, Central America, northern South America.

Please note that all transit contact times are approximate and may differ by several minutes depending on the position of the observer on Earth and the local atmospheric conditions.
22:09 UT \| 5 June	First contact. Venus is externally tangent to the Sun's disc.
22:27 UT \| 5 June	Second contact. Venus is internally tangent to the Sun's disc.
01:29 UT \| 6 June	Middle of the transit.
04:31 UT \| 6 June	Third contact. Venus is internally tangent to the Sun's disc.
04:49 UT \| 6 June	Fourth contact. Venus is externally tangent to the Sun's disc.
Total Solar Eclipse : 13-14 November
Your eyesight is precious! Protect it!
Total Eclipse Visibility:	Western Australia, the southern Pacific Ocean.
Partial Eclipse Visibility:	Australia, southern Pacific Ocean, southern South America.

19:37 UT \| 13 November	The partial eclipse begins.
20:35 UT \| 13 November	The total eclipse begins.
22:08 UT \| 13 November	New Moon.
22:12 UT \| 13 November	Instant of greatest eclipse: magnitude = 1.05
23:48 UT \| 13 November	The total eclipse ends.
00:45 UT \| 14 November	The partial eclipse ends.
Penumbral Lunar Eclipse : 28 November
Complete eclipse visible:	Most of India, Asia, Australia, New Zealand, the Pacific Ocean, Alaska, northwestern Canada.
Moon eclipsed at moonrise:	Most of Europe and Africa, the Middle East.
Moon eclipsed at moonset:	Most of the United States, Canada and Mexico.

12:14 UT	The penumbral eclipse begins.
14:33 UT	Greatest eclipse: penumbral magnitude = 0.92
14:46 UT	Full Moon.
16:51 UT	The penumbral eclipse ends.

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