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Eclipse can be either a solar eclipse or a lunar eclipse.


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Eclipse is an astronomical event when one body moves into the shadow of another. Eclipse is most often used to describe either a solar eclipse. Solar eclipse is when the Moon's shadow crosses Earth's surface, or a lunar eclipse, when the Moon moves into the shadow of Earth. However, eclipse can also refer to such events beyond the Earth-Moon system: for example, a planet moving into the shadow cast by one of its moons, a Moon passing into the shadow cast by its parent planet, or a Moon passing into the shadow of another moon. A solar eclipse is actually a misnomer; the phenomenon is actually an occultation.

Eclipse.
The French 1999 eclipse.

The Earth happens to be in the midst of a cosmic coincidence. During a solar eclipse, the Moon perfectly covers the Sun. This is because the Sun is 400 times farther away from the Earth than the Moon and the Sun is 400 times larger than the Moon. This was not the case 100 million years ago (when the Moon was closer to the Earth), and it will cease to be the case in the distant future. An eclipse is a type of syzygy, as are transits and occultations.

Eclipse in the earth-moon cycle.

An eclipse involving the Sun, Earth and Moon can only occur when they are in a line. Because the plane of the orbit of the Moon is tilted with respect to the plane of the orbit of the Earth (the ecliptic), eclipses occur only when the three bodies are near the intersection (the node) of these planes. The Sun passes either node once a year, and eclipses occur in a period of about two draconic months around these times. There can be from four to seven eclipses in a calendar year. They repeat according to eclipse cycles.

Types of eclipse.

solar eclipse.
1999 Total solar eclipse seen from the Mir space station.

The most dramatic eclipses visible from Earth are:

  • Lunar eclipses - the Earth obscures the Sun, from the Moon's point of view. The Moon moves through the shadow cast by the Earth. This can only happen at full moon.
  • Solar eclipses - the Moon occults the Sun, from the Earth's point of view. The Moon casts a shadow that touches the surface of the Earth. This can only happen at new moon. .
  • Eclipses can be divided into different types:

  • Total eclipses, in which the light source is totally blocked off by the eclipsing body. For total solar eclipses, the viewer is in the umbra part of the Moon's shadow. The total phase of a total eclipse can have a duration of up to 7 min 31 s. .
  • Partial eclipses, in which only part of the luminary is covered (solar eclipses), or when only part of a body is eclipsed by the shadow (lunar eclipses). For solar eclipses, the viewer is in the penumbra part of the Moon's shadow. .
  • Annular eclipse, which are a total eclipse of luminary where a thin ring of light is visible around the intervening object. For solar eclipses, the viewer is in the antumbra part of the Moon's shadow. .
  • Hybrid solar eclipses, which consists of three phases: the eclipse starts as an annular one, then turns into a total and by the end it returns to the annular phase. The total phase of a hybrid eclipse is typically very short. Maximum possible duration is 1 min 49 s. It is pure coincidence that the Moon and Sun have nearly equal apparent sizes, making hybrid solar eclipses possible. .

The ratio between the apparent sizes of the eclipsing body and that of the luminary is called the magnitude of the eclipse. For solar eclipses, the ratio varies around 1, being sometimes more than 1, sometimes less. For lunar eclipses, the magnitude is much larger than 1; they never appear annular (viewed from the Moon).

Eclipse phases.

These were used in occult ceremonies.

General phases of a solar eclipse.

  • The general eclipse begins when the Moon's penumbra cone starts to sweep across the Earth's disc. .
  • The total or annular eclipse begins when the Moon's umbra starts to sweep across the Earth's disc. .
  • The centrality begins when the axis of the Moon's shadow cone starts to sweep across the Earth's disc. .
  • The eclipse's maximum occurs when the terrestrial surface within the umbra reaches its largest area. .
  • The centrality ends when the axis of the Moon's shadow finishes its sweep across the Earth's disc.
  • The total or annular eclipse ends when the Moon's shadow finishes its sweep across the Earth's disc. .
  • The general eclipse ends when the Moon's penumbra finishes its sweep across the Earth's disc. .

Local phases of a solar eclipse.

1999 eclipse.
The French 1999 eclipse.

  • First contact (also called first exterior contact) is the instant when the Moon's disc starts to cover the Sun's. .
  • Second contact (also called first interior contact) is the instant when the Moon's disc is entirely surrounded by the Sun's (for an annular eclipse) or the instant when the Sun's disc disappears completely behind the Moon's (for a total eclipse). .
  • Third contact (also called second interior contact) is the instant when the Moon's disc starts to come out of the Sun's (for an annular eclipse) or the instant when the Sun's disc reappears from behind the Moon's (for a total eclipse). .
  • Lastly, fourth contact (also called second exterior contact) is the instant when the Moon's disc clears the Sun's. .

Phases of a lunar eclipse.

lunar eclipse.
The progression of a lunar eclipse.

There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's umbra; and total, when the Moon crosses entirely within the Earth's umbra.

  • First contact (also called first exterior contact) is the instant when the Moon starts to enter into the Earth's umbra..
  • Second contact (also called first interior contact) is the instant when the Moon enters completely into the Earth's umbra. This is the beginning of totality. .
  • The maximum of the eclipse occurs when the angular distance between the centre of the Moon's disc and the centre of the shadow cone is at its smallest value. .
  • Third contact (also called second interior contact) is the instant when the Moon starts to come out of the Earth's umbra. This is the end of totality. .
  • Lastly, fourth contact (also called second exterior contact) is the instant when the Moon clears the Earth's umbra completely. .

Eclipse in mythology.

Han Dynasty Carving.
Han Dynasty Carving.

Before modern astronomy arose there were long-standing explanations for eclipses in many cultures. These would typically involve conflicts between mythic forces. For example, in Hindu mythology, the two demons Rahuand Ketu were believed to be the cause of eclipses. However Aryabhata gave an accurate explanation of the eclipse in his scientific treatise Aryabhatiya dated 499 AD

Similarly in China, at the Imperial observatory in Beijing, is a carved stone with the following explanation:

In this explanation we see a recognition of the celestial realities and a cheerful outlook regarding the event. In other cultures an eclipse could be both a surprising and a terrifying event.

"This carved stone chart explained the cause of solar eclipses. The center of the golden bird (the symbol of the sun) was covered by the toad (the symbol of the moon). The people of the Han Dynasty called the phenomenon a good combination of the Sun and the moon."

Eclipses elsewhere in the solar system. Eclipses are impossible on Mercury and Venus, which have no moons.

Jupiter and its Moon Io.
A picture of Jupiter and its Moon Io taken by Hubble. The black spot is Io's shadow.

On Mars, only partial eclipses are possible, because neither of its moons is large enough to cover the Sun's disc. Martian eclipses have been photographed from both the surface of Mars and from orbit. See Transit of Phobos from Mars and Shadow of Phobos on Mars.

The gas giants, which have many moons, frequently display eclipses. The most striking involve Jupiter, which has four large moons and a low axial tilt, making eclipses more frequent. It is common to see the larger moons casting circular shadows upon Jupiter's cloudtops.

Pluto, with its large Moon Charon, is also the site of many eclipses.

Eclipses.

Penumbral Lunar Eclipse, April 24.

Apr 21, 2005 - There's going to be a partial lunar eclipse on Sunday, April 24; unfortunately, the Moon will only pass through the faint penumbral shadow, and only dim slightly. Most observers would be hard-pressed to tell the difference. The eclipse gets going at 0955 UT (5:55 am EDT) and ends about 2 hours later. Observers in the Americas should be able to see the eclipse, with the best view for folks in the West.

Solar Eclipse: April 8, 2005

Apr 1, 2005 - There will be a total solar eclipse next Friday, but unless you're floating in the middle of the Pacific Ocean, you'll have to settle for a partial view. The Moon's shadow will touch down Southeast of New Zealand, and then make its way across the Pacific Ocean, briefly crossing Central America. Most of the South Pacific, and North/South America will see a partial solar eclipse, depending on their distance from the path of totality.

Lunar Eclipse Tonight!

Oct 27, 2004 - Okay, here's your last reminder. There's going to be a total lunar eclipse tonight, visible from the Americas, Europe and Africa. This is going to be the last eclipse visible until 2007, so I suggest that you set some time aside to enjoy this natural wonder. You don't need any special equipment, just head outside, and watch the Moon as it darkens and then turns a beautiful red colour.

Here's an article about the eclipse that was posted a few weeks ago, and a full list of astrocameras that will be broadcasting the eclipse onto the Internet.

Total Lunar Eclipse: October 27/28

Oct 26, 2004 - September’s full moon, better known as the Harvest Moon was everything we've come to expect in the fall; a large, warmly glowing golden ball peeking above the trees just after sunset. But the splendors of several consecutive nights of beautiful moonlight can’t compare to the show the Moon will put on in late October. October offers us a chance to see a truly amazing spectacle, a total lunar eclipse on October 27/28th. Click here for a full list of astrocameras broadcasting the eclipse live on the Internet.

Reminder: Plan for the Lunar Eclipse

Oct 22, 2004 - As we reported a week ago, there's going to be a lunar eclipse on October 27/28 which will be visible from the Americas and Western Europe. This'll be the last chance to see a total lunar eclipse for a while, so I highly suggest - no, I demand - that you set aside some time on Wednesday evening to enjoy it. We're having an eclipse party with some friends.

Lunar Eclipse Tonight

May 4, 2004 - People on five continents will be treated to a total lunar eclipse tonight, with the best views from western Asia. The visible eclipse will begin at 1851 UTC, and reach its maximum at 2030 UTC. Unfortunately, it won't be visible at all from North or South America, as it happens during the day there. Of course, there are live astrocameras covering this event, weather permitting, so you can see it through the Internet. There's one in the Netherlands, and another in Iran.

Antarctica Sees a Total Solar Eclipse

Nov 24, 2003 - scientists and tourists saw the first total solar eclipse from the continent of Antarctica in over a century on Sunday. Because of its remote location, some people chose to fly in two airplanes that followed the path of the eclipse, while others waited on an icebreaker. Some people also saw the eclipse from a few of the scientific outposts on the continent that were under the path of totality. The point of the greatest eclipse only lasted for one minute, 55 seconds. The next total eclipse will be in April 2005, and only be visible from the middle of the Pacific Ocean.

Total Solar Eclipse Over Antarctica on November 23

Nov 20, 2003 - Some residents of Antarctica will have the opportunity to see a total solar eclipse on November 23, 2003. Since that's mostly just penguins, Astronomers and tourists are travelling to the path of totality in boats and airplanes - to be at the right place at the right time when the eclipse happens. Passengers in a moving aircraft will be able to watch the eclipse for a total 2 minutes, 36 seconds, while people on the ground will only see it for less than 2 minutes.

Total Lunar Eclipse Was a Treat on Saturday Night

Nov 9, 2003 - Skywatchers from Alaska to Eastern Europe were treated to a total lunar eclipse on Saturday night, when the Moon dipped behind the Earth's shadow. Chunks of the Moon began to disappear at 2332 universal time (6:32 pm EST), and then it turned a coppery red about two hours later. And then four hours after it started, the eclipse was over. Many observers said it was one of the brightest eclipses they'd seen in recent years. If you missed this show, don't worry, there are two more lunar eclipses coming in 2004. Then a break; there won't be another total lunar eclipse visible until 2007.

Another Reminder: Lunar Eclipse November 8-9, 2003

Nov 6, 2003 - Just in case you'd forgotten, here's another reminder of Saturday's total lunar eclipse, visible from most of the Americas, Europe and Africa. The visible eclipse begins at 2332 GMT (6:32 pm EST) and the maximum happens at 0119 GMT Sunday (8:19 pm EST Saturday). The Moon is just going to skim inside the Earth's shadow, so it won't be a long eclipse, but you should still be able to see it turn dark and then a coppery red colour before exiting the shadow again. If you can't see the eclipse where you live, return to universe Today - we'll be showcasing various astrocameras around the world broadcasting the eclipse live.

Total Lunar Eclipse - November 8-9, 2003


Oct 22, 2003 - Mark your calendars for an astronomical event that you don't want to miss. In the early morning of Sunday, November 9, most of the Western Hemisphere and Europe will be treated to a total lunar eclipse. And universe Today is going to be gathering together a network of astrocameras, so you can watch it on the Internet if the weather doesn't cooperate for you.

Northern Europe Treated to Eclipse Show

Jun 1, 2003 - Skywatchers in Northern Europe were treated to a show on Saturday, May 31 when the Moon passed in front of the Sun and created an annular eclipse. Astrocameras at the Copernicus Public Observatory in the Netherlands and the Mira Public Observatory in Belgium caught the whole event live, and dozens of amateur Astronomers across Europe have submitted their own photos as well. The next solar eclipse will be on November 23, but will only be visible from Antarctica.

Watch a Solar Eclipse on Saturday

May 30, 2003 - On Saturday, May 31 an annular eclipse of the Sun will be visible from most of the Northern Hemisphere. The moon's shadow will start in Northern Scotland and then sweep across Iceland and Greenland. Just in case you won't be able to see it in your own sky, a group of Astronomers in the Netherlands and Belgium will be broadcasting live pictures of the eclipse on the Internet. Coverage will begin at approximately 0320 GMT and end about 45 minutes later.

Northern Europe's Annular Eclipse: May 31, 2003

May 25, 2003 - On Saturday, May 31, an annular eclipse of the Sun will be visible from a good portion of the Northern Hemisphere. The best views will be in northern Scotland, Iceland and Greenland where the Sun will be visible as a ring of fire behind the moon, but even a partial eclipse will be visible from most of Europe, Northern Canada, the Middle East, and Asia. An annular eclipse occurs because the Moon's orbit isn't a perfect circle. If the Moon is at the closest part of its orbit when it passes in front of the Sun, it causes a total eclipse - at the furthest point, it's an annular eclipse.

Lunar Eclipse Puts on a Show

May 16, 2003 - People with clear skies Thursday night were treated to a total lunar eclipse. The eclipse began at 0203 (10:03pm EDT) and ended approximately three hours later. The weather wasn’t entirely cooperating; however, many astrocameras poised around North America and Europe ended up being rained out. The next lunar eclipse will be on November 9, 2003, and will be visible from roughly the same parts of the Earth – only this time it’ll be brighter.

May 15, 2003 -

The May 15-16 Total Lunar Eclipse has begun! The eclipse started at 10:03pm EDT (0203 GMT). Astrocameras from around the world are capturing the event live.

Lunar Eclipse Tonight

May 15, 2003 - The Americas and part of Europe will be treated to a total eclipse of the Moon on Thursday night – the first one visible here in three years. A lunar eclipse occurs when the Earth’s shadow falls on the Moon, turning it a deep red colour. Unlike solar eclipses, lunar eclipses are completely safe to watch with the naked eye; and it looks even better with a pair of binoculars or small telescope. The eclipse begins at 0203 GMT Friday (10:03pm EDT Thursday), and reaches the maximum at 0340 GMT (11:40pm EDT). The eclipse will be best viewed from the Eastern Coast of the United States.

Links For Eclipses.

Eclipse Chasers - Solar and Lunar eclipse observing, photography, and travel for beginners through advanced chasers.
Eric's Black Sun Eclipse - Accounts and more about eclipses. Also you can sign up for eclipse space newsletter.
High Moon, the home of Klipsi - Eclipses, Occultations, Leonids, webcam.
UK solar eclipse group - formed to coordinate eclipse events during the 1999 eclipse here in the UK.
Betelgeuse
Cornish Eclipse Camping
Earthview Eclipse Homepage
Eclipse Chaser
Eclipse Shades
Eclipse Zone
Eclipses in Europe
Mr. Eclipse
MrEclipse.com
Solar Eclipse
Solar Eclipse 99
Wayward Bus Eclipse tour




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