What creates a total solar eclipse? - Andy Cohen

1,093,147 views ใƒป 2013-07-22

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: benyamin zinshtein ืขืจื™ื›ื”: Ido Dekkers
00:06
On August 21, 2017
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ื‘ 21 ื‘ืื•ื’ื•ืกื˜ 2017
00:08
the shadow of the Moon will pass
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ืฆืœ ื”ื™ืจื— ื™ื—ืœื•ืฃ
00:09
from the west coast to the east coast of the U.S.
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ืžื”ื—ื•ืฃ ื”ืžืขืจื‘ื™ ืœื—ื•ืฃ ื”ืžื–ืจื—ื™ ืฉืœ ืืจื”"ื‘.
00:12
Our blue sky will turn black as night
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ื”ืฉืžื™ื™ื ื”ื›ื—ื•ืœื™ื ืฉืœื ื• ื™ืขืฉื• ืฉื—ื•ืจื™ื ื›ืžื• ื”ืœื™ืœื”
ื•ื™ืชืžืœืื• ื›ื•ื›ื‘ื™ื,
00:14
and fill with stars,
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00:15
and there will be a hole in the sky
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ื•ื™ื”ื™ื” ื—ื•ืจ ื‘ืฉืžื™ื™ื
00:16
where the Sun used to be,
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ืื™ืคื” ืฉื”ืฉืžืฉ ื ื”ื’ื” ืœื”ื™ื•ืช,
00:18
surrounded by the fiery ring of the Sun's corona,
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ืžื•ืงืฃ ื‘ื˜ื‘ืขืช ืœื•ื”ื˜ืช ืฉืœ ืขื˜ืจืช ื”ืฉืžืฉ,
00:20
a total eclipse of the Sun.
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ืœื™ืงื•ื™ ื—ืžื” ืžืœื.
00:22
This will truly be a historic event.
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ื–ื” ื‘ืืžืช ื™ื”ื™ื” ืื™ืจื•ืข ื”ื™ืกื˜ื•ืจื™.
00:24
Accounts of solar eclipses
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ื‘ื”ืชื—ืฉื‘ ื‘ืจืฉื•ืžื•ืช ื›ืชื•ื‘ื•ืช ืขืชื™ืงื•ืช
00:25
date way back on the written record.
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ื‘ื ื•ื’ืข ืœืœื™ืงื•ื™ื™ ื—ืžื”.
00:27
The early Mesopotamians wrote
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ื”ืžืกืคื•ื˜ืžื™ื ื”ืงื“ื•ืžื™ื ื›ืชื‘ื•
00:29
that the Sun was put to shame
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ืฉื”ืฉืžืฉ ื‘ื•ื™ืฉื”
00:30
during the solar eclipse of the 14th century B.C.E.
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ื‘ืžื”ืœืš ืœื™ืงื•ื™ ื—ืžื” ืฉืœ ื”ืžืื” ื”-14 ืœืคื ื™ ื”ืกืคื™ืจื”.
00:33
and it may have started
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ื•ื–ื” ืื•ืœื™ ื”ืชื—ื™ืœ
00:34
the Sun worship of the Egyptian pharaoh Akhenaten.
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ืืช ื”ืกื’ื™ื“ื” ืืœ ื”ืฉืžืฉ ืฉืœ ื”ืคืจืขื” ื”ืžืฆืจื™ ืื—ื ืชืŸ.
00:37
Ancient Chinese astrologers paid with their lives
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ืืกื˜ืจื•ืœื•ื’ื™ื ืกื™ื ื™ื™ื ืงื“ืžื•ื ื™ื ืฉื™ืœืžื• ื‘ื—ื™ื™ื”ื
00:40
if they failed to predict the solar eclipse
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ืื ื”ื ื˜ืขื• ื‘ืœื—ื–ื•ืช ืœื™ืงื•ื™ ื—ืžื”
00:42
and portend the fate of their emperors
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ื•ืืช ื’ื•ืจืœื ืฉืœ ื”ืงื™ืกืจื™ื ืฉืœื”ื
ืฉืกืžืœื ื”ื™ื” ื”ืฉืžืฉ.
00:44
whose symbol was the Sun.
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00:45
The earliest date of a specific event in human history,
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ื”ืชืืจื™ืš ื”ืžื•ืงื“ื ื‘ื™ื•ืชืจ ืฉืœ ืื™ืจื•ืข ืกืคืฆื™ืคื™ ื‘ื”ื™ืกื˜ื•ืจื™ื” ืฉืœ ื”ืื ื•ืฉื•ืช,
ืงืจื‘ ื‘ื™ืŸ ื”ืฆื‘ืื•ืช ืฉืœ ืœื™ื“ื™ื” ื•ืžื“ื™ื”,
00:48
a battle between the armies of Lydia and Media,
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00:50
occurred on May 28, 535 B.C.E.
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ื”ืชืจื—ืฉ ื‘ 28 ื‘ืžืื™ 535 ืœืคื ื™ ื”ืกืคื™ืจื”.
00:53
when a solar eclipse caused the soldiers
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ื›ืืฉืจ ืœื™ืงื•ื™ ื—ืžื” ื’ืจื ืœื—ื™ื™ืœื™ื
00:55
to lay down their arms and declare a truce.
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ืœื”ื ื™ื— ืืช ื ืฉืงื ื•ืœื”ื›ืจื™ื– ื”ืคืกืงืช ืืฉ.
00:57
So how does it happen?
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ืื– ืื™ืš ื–ื” ืงืจื”?
00:59
During a total solar eclipse,
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ื‘ืžื”ืœืš ืœื™ืงื•ื™ ื—ืžื” ืžืœื,
01:01
the Moon moves between the Earth and the Sun.
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ื”ื™ืจื— ืžืชืžืงื ื‘ื™ืŸ ื›ื“ื•ืจ ื”ืืจืฅ ืœื‘ื™ืŸ ื”ืฉืžืฉ.
01:04
When this happens, the disc of the Moon
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ื›ืืฉืจ ื–ื” ืงื•ืจื”, ื ืจืื” ืฉื“ืกืงืช ื”ื™ืจื—
01:06
appears to perfectly cover the disc of the Sun
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ืžื›ืกื” ื‘ื“ื™ื•ืง ืืช ื“ืกืงืช ื”ืฉืžืฉ
01:08
even though the Sun is much larger than the Moon.
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ืœืžืจื•ืช ืฉื”ืฉืžืฉ ื’ื“ื•ืœื” ื‘ื”ืจื‘ื” ืžืืฉืจ ื”ื™ืจื—.
01:11
But how is this possible?
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ืื‘ืœ ืื™ืš ื–ื” ืืคืฉืจื™?
01:13
The Sun is 400 times bigger than the Moon,
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ื”ืฉืžืฉ ื’ื“ื•ืœื” ืคื™ 400 ืžื”ื™ืจื—,
01:15
but by sheer coincidence,
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ืื‘ืœ ืžืžืงืจื™ื•ืช ื‘ืœื‘ื“,
01:16
the Moon is 390 times closer to Earth.
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ื”ื™ืจื— ืคื™ 390 ืงืจื•ื‘ ื™ื•ืชืจ ืœื›ื“ื•ืจ ื”ืืจืฅ ืžืืฉืจ ื”ืฉืžืฉ.
01:18
Size and distance cancel each other out
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ื”ืžืจื—ืง ื•ื”ื’ื•ื“ืœ ืžื‘ื˜ืœื™ื ืืช ืื—ื“ ื”ืฉื ื™
01:20
so that the Moon and Sun appear
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ื›ืš ืฉื”ืฉืžืฉ ื•ื”ื™ืจื— ื ืจืื™ื
01:22
to be almost the exactly same size.
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ื›ืžืขื˜ ื‘ื“ื™ื•ืง ื‘ืื•ืชื• ื’ื•ื“ืœ.
01:24
Every time the Moon orbits the Earth,
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ื›ืœ ืคืขื ืฉื”ื™ืจื— ืžืงื™ืฃ ืืช ื›ื“ื•ืจ ื”ืืจืฅ,
01:26
once every 27.3 days,
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ืกื™ื‘ื•ื‘ ื‘ื›ืœ 27.3 ื™ืžื™ื,
01:28
it has to pass between the Earth and the Sun,
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ื”ื•ื ื—ื•ืœืฃ ื‘ื™ืŸ ื”ืฉืžืฉ ืœื‘ื™ืŸ ื›ื“ื•ืจ ื”ืืจืฅ,
01:31
a stage called the new moon phase.
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ืฉืœื‘ ื”ื ืงืจื ืžื•ืœื“ ื™ืจื—.
01:33
And every time it passes,
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ื•ื›ืœ ืคืขื ืฉื”ื•ื ื—ื•ืœืฃ,
01:35
the New Moon has a chance to block out the Sun.
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ืœื™ืจื— ื ื•ืœื“ ื™ืฉ ืกื™ื›ื•ื™ ืœื—ืกื•ื ืืช ื”ืฉืžืฉ.
01:38
Most of the time,
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ืจื•ื‘ ื”ื–ืžืŸ,
01:39
the Moon passes a little above
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ื”ื™ืจื— ื—ื•ืœืฃ ืžืขื˜ ืžืขืœ
01:40
or a little below the Sun,
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ืื• ืžืขื˜ ืžืชื—ืช ืœืฉืžืฉ,
01:41
but if they align perfectly,
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ืื‘ืœ ืื ื”ื ืžืชื™ื™ืฉืจื™ื ื‘ื“ื™ื•ืง,
01:43
the shadow of the Moon
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ืฆืœ ื”ื™ืจื—
01:44
will make a narrow path across Earth
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ื™ื™ืฆื•ืจ ื ืชื™ื‘ ืฆืจ ืœืื•ืจืš ื›ื“ื•ืจ ื”ืืจืฅ
01:46
and those in the shadows will see a total solar eclipse.
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ื•ืืœื” ืฉื ืžืฆืื™ื ื‘ืฆืœ ื™ืจืื• ืœื™ืงื•ื™ ื—ืžื” ืžืœื.
01:49
Just like on night side of the Earth,
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ื‘ื“ื™ื•ืง ื›ืžื• ื‘ืฆื“ ื”ื—ืฉื•ืš ืฉืœ ื›ื“ื•ืจ ื”ืืจืฅ,
01:51
the sky during a total eclipse is black
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ื‘ืฉืžื™ื™ื ื‘ืžื”ืœืš ืœื™ืงื•ื™ ื—ืžื” ืฉื—ื•ืจื™ื
01:53
and filled with stars.
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ื•ืžืœืื™ื ื‘ื›ื•ื›ื‘ื™ื.
01:54
But while the moon perfectly covers
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ืื‘ืœ ื‘ื–ืžืŸ ืฉื”ื™ืจื— ืžื›ืกื” ื‘ื“ื™ื•ืง
01:56
the surface of the Sun,
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ืืช ืฉื˜ื— ื”ืฉืžืฉ,
01:57
it doesn't block out the Sun's outer atmosphere,
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ื”ื•ื ืœื ื—ื•ืกื ืืช ื”ืื˜ืžื•ืกืคื™ืจื” ื”ื—ื™ืฆื•ื ื™ืช ืฉืœ ื”ืฉืžืฉ,
01:59
its corona, which appears as a fiery ring
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ื”ืงื•ืจื•ื ื”, ืฉื ืจืื™ืช ื›ืžื• ื˜ื‘ืขืช ืœื•ื”ื˜ืช
02:02
around the dark disc of the moon.
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ืžืกื‘ื™ื‘ ืœื“ื™ืกืง ื”ืฉื—ื•ืจ ืฉื”ื•ื ื”ื™ืจื—.
02:05
Solar eclipses occur several times a year,
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ืœื™ืงื•ื™ื™ ื—ืžื” ืžืชืจื—ืฉื™ื ื›ืžื” ืคืขืžื™ื ื‘ืฉื ื”,
02:07
but most often they are partial eclipses
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ืื‘ืœ ืœืจื•ื‘ ื”ื ืœื™ืงื•ื™ื™ ื—ืžื” ื—ืœืงื™ื™ื
02:09
where the Moon doesn't quite line up with the Sun.
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ื›ืืฉืจ ื”ื™ืจื— ืœื ืœื’ืžืจื™ ืžืชื™ื™ืฉืจ ืขื ื”ืฉืžืฉ
02:11
And, when the Moon and Sun are perfectly aligned,
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ื•ื›ืืฉืจ ื”ื™ืจื— ื•ื”ืฉืžืฉ ืžืชื™ื™ืฉืจื™ื ื‘ื“ื™ื•ืง,
02:14
the Moon is usually too far from Earth in its orbit
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ื”ื™ืจื— ืœืจื•ื‘ ืจื—ื•ืง ืžื“ื™ ืžื›ื“ื•ืจ ื”ืืจืฅ ื‘ืžืกืœื•ืœ ืฉืœื•
02:16
to completely cover the Sun,
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ื›ื“ื™ ืœื’ืžืจื™ ืœื›ืกื•ืช ืืช ื”ืฉืžืฉ,
02:17
creating an annular eclipse.
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ืžื” ืฉื™ื•ืฆืจ ืœื™ืงื•ื™ ื˜ื‘ืขืชื™.
02:20
During an annular or partial eclipse,
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ื‘ืžื”ืœืš ืœื™ืงื•ื™ ื˜ื‘ืขืชื™ ืื• ืœื™ืงื•ื™ ื—ืœืงื™,
02:22
the sky remains bright.
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ื”ืฉืžื™ื™ื ื ืฉืืจื™ื ื‘ื”ื™ืจื™ื.
02:23
Even on those rare occasions of a total eclipse,
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ืืคื™ืœื• ื‘ืžืงืจื™ื ื ื“ื™ืจื™ื ืฉืœ ืœื™ืงื•ื™ ืžืœื,
02:26
the Moon's shadow is most likely to fall
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ืกื‘ื™ืจ ืœื”ื ื™ื— ื›ื™ ืฆืœ ื”ื™ืจื— ื™ืคื•ืœ
02:28
on the 70% of Earth that is covered by water,
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ื‘ืžื™ื ืฉืœ ื›ื“ื•ืจ ื”ืืจืฅ ืฉืžื”ื•ื•ื™ื 70% ืžืฉื˜ื—ื•
02:30
and few people, if any, will see it.
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ื•ืื ืฉื™ื ืกืคื•ืจื™ื ืื ื‘ื›ืœืœ ื™ืจืื• ืื•ืชื•.
02:33
The eclipse of 2017 will be remarkable on a larger scale
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ื”ืœื™ืงื•ื™ ืฉืœ 2017 ื™ื”ื™ื” ืžื“ื”ื™ื ื‘ืงื ื” ืžื™ื“ื” ื’ื“ื•ืœ ื™ื•ืชืจ
02:37
because the Moon is slowly moving away from Earth.
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ื‘ื’ืœืœ ืฉื”ื™ืจื— ื–ื– ื‘ืื™ื˜ื™ื•ืช ื”ืจื—ืง ืžื›ื“ื•ืจ ื”ืืจืฅ.
02:39
If a furry ancestor of ours had bothered to look up
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ืื ืื‘ ืงื“ืžื•ืŸ ืžื–ื•ืงืŸ ืฉืœื ื• ื”ื™ื” ื˜ื•ืจื— ืœื”ื‘ื™ื˜ ืžืขืœื”
02:42
during a solar eclipse a hundred million years ago,
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ื‘ืžื”ืœืš ืœื™ืงื•ื™ ื—ืžื” ืœืคื ื™ ืžืื•ืช ืžื™ืœื™ื•ื ื™ ืฉื ื™ื,
02:44
it wouldn't have seen the fiery corona of the Sun.
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ื”ื•ื ืœื ื”ื™ื” ืจื•ืื” ืืช ื”ืงื•ืจื•ื ื” ื”ืœื•ื”ื˜ืช ืฉืœ ื”ืฉืžืฉ.
02:47
It would have just been dark.
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ืคืฉื•ื˜ ื”ื™ื” ื—ื•ืฉืš.
02:48
Eventually, the Moon will have moved too far from Earth
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ื‘ืกื•ืฃ, ื”ื™ืจื— ื™ืชืจื—ืง ืžื“ื™ ืžื›ื“ื•ืจ ื”ืืจืฅ
02:51
to completely cover the disc of the Sun.
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ืขืœ ืžื ืช ืœื’ืžืจื™ ืœื›ืกื•ืช ืืช ื”ืฉืžืฉ.
02:53
It is only during our little wink of Earth's history
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ื–ื” ืจืง ื‘ื–ืžืŸ ื”ืงืฆืจ ืฉืœื ื• ื‘ื”ื™ืกื˜ื•ืจื™ื™ืช ื›ื“ื•ืจ ื”ืืจืฅ
02:55
that the Moon is at just the right distance
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ืฉื”ื™ืจื— ื”ื•ื ื‘ื“ื™ื•ืง ื‘ืžืจื—ืง ื”ืžืชืื™ื
02:57
to cause a total solar eclipse
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ืขืœ ืžื ืช ืœื’ืจื•ื ืœืœื™ืงื•ื™ ื—ืžื” ืžืœื
02:59
yet not block the Sun's corona.
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ืืš ืœื ืœื—ืกื•ื ืืช ื”ืงื•ืจื•ื ื” ืฉืœ ื”ืฉืžืฉ.
03:01
So on August 21, 2017,
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ืื– ื‘ 21 ื‘ืื•ื’ื•ืกื˜ 2017,
03:04
when the Moon exactly lines up with the Sun
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ื›ืืฉืจ ื”ื™ืจื— ื™ืชื™ื™ืฉืจ ื‘ื“ื™ื•ืง ืžื•ืœ ื”ืฉืžืฉ
03:06
and the Moon is close enough to the Earth,
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ื•ื”ื™ืจื— ื™ื”ื™ื” ืžืกืคื™ืง ืงืจื•ื‘ ืœื›ื“ื•ืจ ื”ืืจืฅ,
03:08
its shadow will cross the U.S.
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ื”ืฆืœ ืฉืœื• ื™ื—ืฆื” ืืช ืืจืฆื•ืช ื”ื‘ืจื™ืช.
03:09
and, if you happen to be in its narrow path,
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ื•ืื ืืชื ื‘ืžืงืจื” ืชื”ื™ื” ื‘ื ืชื™ื‘ ื”ืฆืจ ืฉืœื•,
03:12
you will witness one of the most
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ืืชื ืชื—ื–ื• ื‘ืื—ื“
03:13
awe-inspiring sights in the universe.
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ื”ืžื—ื–ื•ืช ื”ืžืจืฉื™ืžื™ื ื‘ื™ืงื•ื.
03:15
But, as incredible as this event will be,
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ืื‘ืœ, ืขื“ ื›ืžื” ืฉื”ืื™ืจื•ืข ื”ื–ื” ื™ื”ื™ื” ืžื“ื”ื™ื,
03:18
total eclipses are one of the most dangerous as well.
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ืœื™ืงื•ื™ ื—ืžื” ืžืœื ื”ื•ื ื’ื ืื—ื“ ื”ืื™ืจื•ืขื™ื ื”ืžืกื•ื›ื ื™ื.
03:20
Only specially tinted filters,
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ืจืง ืคื™ืœื˜ืจื™ื ื›ื”ื™ื ืžื™ื•ื—ื“ื™ื,
03:22
specifically designed to observe the Sun,
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ื”ืžื™ื•ืขื“ื™ื ื‘ืžื™ื•ื—ื“ ืœืฆืคื™ื™ื” ื‘ืฉืžืฉ,
03:24
should be used.
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ืฆืจื™ื›ื™ื ืœื”ื™ื•ืช ื‘ืฉื™ืžื•ืฉ.
03:25
The eclipse might put the Sun to shame,
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ื”ืœื™ืงื•ื™ ืื•ืœื™ ื™ืฉื™ื ืืช ื”ืฉืžืฉ ืœื‘ื•ืฉื”,
03:27
but even a shamed Sun
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ืื‘ืœ ืืคื™ืœื• ืฉืžืฉ ืžื‘ื•ื™ืฉืช
03:28
can seriously damage your eyes.
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ื™ื›ื•ืœื” ืœื’ืจื•ื ืœื ื–ืง ืžืฉืžืขื•ืชื™ ื‘ืขื™ื ื™ื™ื.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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