by JohnD » Sat Mar 28, 2015 11:21 am
In a previous thread about this eclipse, I asked if the fact that this occurred at the time of a "super-moon" would mean that there would be no "Baily's Beads", because the apparently larger Moon would cover the whole of the Sun's disc at totality. I didn't get an answer.
Baily's Beads occur at totality, when the Moon only JUST matches the Sun's diameter. The Moon has deep valleys that the sun shines through around the terminator. They can occur anywhere around the disc, and a very good example is shown on this website, about the recent eclipse:
http://www.naasbeginners.co.uk/News/Sol ... ch2015.htm About half way down. Multiple 'beads' all around the disc.
Conversely, this Apod shows only one bright spot either just before or just after totality. This is the "Diamond Ring" effect that has a different origin. In the moments when the Moon's disc leaves one speck of the Sun visible just before it achieves totality, or moves away revealing the Sun again, that tiny sliver of brilliance appears at one single point on the disc, like a solitaire diamond. That this was also a 'super-moon'
did mean that Baily's Baeds could not be seen this time.
The APOD is a great picture of the Diamond Ring, but does not show Baily's Beads.
The title and description of this APOD should be revised to remove all reference to the Beads.
John
In a previous thread about this eclipse, I asked if the fact that this occurred at the time of a "super-moon" would mean that there would be no "Baily's Beads", because the apparently larger Moon would cover the whole of the Sun's disc at totality. I didn't get an answer.
Baily's Beads occur at totality, when the Moon only JUST matches the Sun's diameter. The Moon has deep valleys that the sun shines through around the terminator. They can occur anywhere around the disc, and a very good example is shown on this website, about the recent eclipse: http://www.naasbeginners.co.uk/News/SolarEclipseMarch2015.htm About half way down. Multiple 'beads' all around the disc.
Conversely, this Apod shows only one bright spot either just before or just after totality. This is the "Diamond Ring" effect that has a different origin. In the moments when the Moon's disc leaves one speck of the Sun visible just before it achieves totality, or moves away revealing the Sun again, that tiny sliver of brilliance appears at one single point on the disc, like a solitaire diamond. That this was also a 'super-moon' [i]did[/i] mean that Baily's Baeds could not be seen this time.
The APOD is a great picture of the Diamond Ring, but does not show Baily's Beads.
The title and description of this APOD should be revised to remove all reference to the Beads.
John