Starship Asterisk*

owlice wrote:Are the white dots showing through the corona stars, or are they artifacts from image processing/manipulation?

owlice wrote:Such beauty, and a vocabulary lesson, too! I had to look up caustics, which led me to another new word nephoid, and then to evolute, involute, and the term circle of confusion (which, previous to today's APOD, I'd have used to refer to the group of friends I had dinner with Sunday evening <g>). Not the first time APOD has made me wish I'd taken more math and physics in my youth.

Are the white dots showing through the corona stars, or are they artifacts from image processing/manipulation?

BMAONE23 wrote:Where were Venus and Mercury at the time of the eclipse?

http://en.wikipedia.org/wiki/Delta_Cancri wrote:
<<Delta Cancri (δ Cnc / δ Cancri) is an orange giant star approximately 180 light-years away in the constellation Cancer. It has the traditional name Asellus Australis which in Latin means "southern donkey colt". It also have had the longest of all known star names "Arkushanangarushashutu", derived from ancient Babylonian[clarification needed] and means "the southeast star in the Crab". Since it is near the ecliptic, it can be occulted by the Moon and very rarely by planets.

Delta Cancri was involved in the first recorded occultation by Jupiter:

"The most ancient observation of Jupiter which we are acquainted with is that reported by Ptolemy in book X, chap. iii (sic), of the Almagest, ...when the planet eclipsed the star known as (Delta) Cancri. This observation was made on September 3, B.C. 240, about 18h on the meridian of Alexandria." —Allen, 1898, quoting from Hind's The Solar System).

Delta Cancri also marks the famous open star cluster Praesepe or the Beehive Cluster also known as Messier 44. In ancient times M44 was used as a weather gauge as the following Greek rhyme from Aratos' Prognostica reveals:

A murky manger with both stars

Shining unaltered is a sign of rain. While if the northern Ass is dimmed By vaporous shroud, he of the south gleam radiant, Expect a south wind: the vaporous shroud and radiance Exchanging stars harbinger Boreas.
—Allen, 1898

The meaning of this verse is that if Asellus Borealis or Gamma Cancris[2] is hidden by clouds, the wind will be from the south and that situation will be reversed if Arkushanangarushashutu is obscured. There is some doubt however as to the accuracy of this as Allen notes: "Our modern Weather Bureau would probably tell us that if one of these stars were thus concealed, the other also would be." (Allen, 1898)

But Delta Cancri also acts as more than just a dubious weather guide – it is a reliable signpost for finding the vividly red star X Cancri as Patrick Moore notes in his Guidebook ‘Stars of the Southern Skies’:

“In the same binocular field with Delta [Cancri] you will find one of the reddest stars in the sky: X Cancri. It is a semi-regular variable; at maximum it rises to magnitude 5 and it never falls below 7.3 so that it can always be seen with binoculars. It looks rather like a tiny glowing coal.” —Page 146, Moore, 1994.

Delta Cancri also marks the radiant of the Delta Cancrids meteor shower.

In 1876, the possibility that Delta Cancri has a companion star was proposed.>>

Chris Peterson wrote:These concepts are all very interesting, but I am doubtful that any apply to this image. I think that caustic is misused here, and no caustics are actually visible. The corona is simply too thin and diffuse to introduce significant refraction effects; what we are seeing is different intensities resulting from subtle differences in gas density.
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You'd need to consider the position of the Sun and the imager to tell for certain. The corona is dim enough that stars can be seen through it, so it's very possible that's what we're seeing.

biddie67 wrote:I have to apologize in advance since I suspect you folks think my questions inane but I do have another one: with all the fusion, burning, eruptions, whatever in the sun, does it make any kind of roaring sound that can be heard at any distance from it?

Sound is a travelling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.

So I'm thinking no, unless the sound receptor (whatever it might be) is in the sun, and if so, the sound receptor would be toast, and toast can't hear. (I'm sure someone will correct me if I'm wrong; at least, I certainly hope so!)

It's a perfectly respectable question, IMHO, since our earthly experience includes sound; can be hard to wrap one's head around the silence of a vacuum.