Re: Diamond Ring Effect
- From: Skywise <into@xxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 24 Jul 2005 06:56:44 -0000
"Patrick Delonix" <abcdpqrs@efghwxyz> wrote in
news:11e63bvequ33vcc@xxxxxxxxxxxxxxxxxx:
>
> "redbelly" <redbelly98@xxxxxxxxx> wrote
>
>> The sun's apparent size (excluding corona) is somewhat smaller than the
>> moon during a total solar eclipse, so the effect cannot happen all
>> around the perimeter.
>
> The apparent sizes of the moon and the sun vary as functions of the
> earth-moon distance and the earth-sun distance.
> The sun's apparent size may be larger than the moon's size, almost the
> same or smaller.
>
> BTW what are the so-called "Bailly's [spelling?] Beads"?
Baily's Beads is the proper name for the 'beads' of sunlight that
cause the diamond ring effect. They are named for Francis Baily
who first described them...let me look it up...in 1836.
It is entirely possible - if one were in the right place at the
right time with the right eclipse - to observe Baily's Beads all
around the circumference of the Moon.
In a total eclipse the Moon appears larger than the Sun and so that
as the edge of the Moon grazes the edge of the Sun, the peaks and
valleys along the Moon's limb are a sort of ragged edge. In some
spots the Sun's light can get through. In this type of eclipse this
only happens at second and third contact[*]. There is a small area
along the circumference where the Sun's light is peaking through
brightly and around the rest is the Solar Corona. The corona is the
ring and the Baily's Beads makes the Diamond.
In an annular eclipse the Moon appears smaller than the Sun. Even
at maximum eclipse the Sun is not completely blocked out leaving a
bright ring or annulus of light. The light is so bright that one
cannot see the corona. There could still be some Baily's Beads as
the Moon makes second and third contact
Sometimes the Moon appears almost exactly the same size as the Sun.
When this happens, totality is very brief, maybe a few seconds. At
this moment if circumstances are right, Baily's Beads could appear
all around the Moon. This is a very rare occurance, and actually a
whoel eclipse would not be like this because the Sun/Earth/Moon
distances are constantly changing. As an example, a recent eclipse
started as an annular eclipse and progressed to a total eclipse.
There was a brief moment along a very short part of the path of
totality where the Moon and Sun were the same size. If anyone were
there they could have seen a complete circle of Baily's Beads. In
this example though this point was out in the middle of the ocean.
* There are four 'contacts'. For a total eclipse, first contact is
when the Moon first begins to obscure the Sun. Second contact is
when the Moon begins to completely cover the Sun starting totality.
Third contact is when the other side of the Moon's disk starts to
uncover the Sun thus ending totality. Fourth contact is when the
last bit of the Moon disappears and the eclipse ends.
Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
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Sed quis custodiet ipsos Custodes?
.
- References:
- Diamond Ring Effect
- From: youzpalang
- Re: Diamond Ring Effect
- From: Bob May
- Re: Diamond Ring Effect
- From: youzpalang
- Re: Diamond Ring Effect
- From: redbelly
- Re: Diamond Ring Effect
- From: Patrick Delonix
- Diamond Ring Effect
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