Starship Asterisk*

keel wrote:Re: the pic about Halley's Comet. Seeing this pic, I wondered if an astronaut standing on the surface of the comet would feel/experience that 'wind'. How bad would it be, if at all?

http://apod.nasa.gov/apod/ap100104.html wrote:
<<Formed from the primordial stuff of the Solar System,
comet nuclei were thought to resemble very dirty icebergs.>>

geckzilla wrote:Crud, looks like someone forgot to include the robot's discuss link in the APOD today.

<<It was a strange figure -- like a child: yet not so like a child as like an old man, viewed through some supernatural medium, which gave him the appearance of having receded from the view, and being diminished to a child's proportions. Its hair, which hung about its neck and down its back, was white as if with age; and yet the face had not a wrinkle in it, and the tenderest bloom was on the skin. The arms were very long and muscular; the hands the same, as if its hold were of uncommon strength. Its legs and feet, most delicately formed, were, like those upper members, bare. It wore a tunic of the purest white, and round its waist was bound a lustrous belt, the sheen of which was beautiful. It held a branch of fresh green holly in its hand; and, in singular contradiction of that wintry emblem, had its dress trimmed with summer flowers. But the strangest thing about it was, that from the crown of its head there sprung a bright clear jet of light, by which all this was visible; and which was doubtless the occasion of its using, in its duller moments, a great extinguisher for a cap, which it now held under its arm.

Even this, though, when Scrooge looked at it with increasing steadiness, was not its strangest quality. For as its belt sparkled and glittered now in one part and now in another, and what was light one instant, at another time was dark, so the figure itself fluctuated in its distinctness: being now a thing with one arm, now with one leg, now with twenty legs, now a pair of legs without a head, now a head without a body: of which dissolving parts, no outline would be visible in the dense gloom wherein they melted away. And in the very wonder of this, it would be itself again; distinct and clear as ever.

"Are you the Spirit, sir, whose coming was foretold to me?" asked Scrooge.

"I am." The voice was soft and gentle.
Singularly low, as if instead of being so close beside him, it were at a distance.

"Who, and what are you?" Scrooge demanded.

"I am the Ghost of Christmas Past.">>

bownh wrote:I don't understand the photo. Shouldn't the tail be on the dark side of the comet?
The photo appears to be showing the comet nucleus to be illuminated from the left side, the same direction the tail extends.

edgarhons wrote:In the photo there appears to be a spiral in the plume (easily visible if you tilt a laptop away from you). I understand the comet can spin but this looks more like it is rotating around some center of gravity. Is this just a camera effect or is something actually spiraling around in there?

BMAONE23 wrote:I would say that it is most likely the Dust Trail that is seen in the image. The Dust Trail forms behind the cometary nucleus, opposite the direction of travel so if the comet were outbound in this image, the dust tail would be lit up and the face of the cometary body would be dark.

http://antwrp.gsfc.nasa.gov/apod/ap960328.html wrote:

<<NASA's Hubble Space Telescope captured this image of the near-nuclear region of Comet Hyakutake on March 25 as the comet approached within 9.3 million miles of the Earth. It covers a relatively "small" 2,000 mile wide area with the sunward direction toward the lower right (tailward is upper left). The image shows large amounts of dust jetting from the sunward side of the nucleus as the sun heats the surface of this dirty "orbiting iceberg". Pressure from sunlight eventually pushes the dust tailward and as the dust production increases, the already visually impressive tail will grow even brighter! The actual size of the nucleus is uncertain but is estimated to be 5-10 miles, similar to Comet Halley. As seen here, the brightest point is probably the tip of the strongest dust jet rather than the nucleus itself. A dramatic dust jet feature also appears to arise from the nightside but its true angle to our line of sight is difficult to judge. Some large fragments which have broken away from the comet nucleus are visible in the upper left of the image, producing dust tails of their own. Comet dust may represent primordial material from the formation of the solar system and NASA has plans for a comet dust sample return mission. >>