APOD: Despina, Moon of Neptune (2014 Jan 16)

Post a reply


This question is a means of preventing automated form submissions by spambots.
Smilies
:D :) :ssmile: :( :o :shock: :? 8-) :lol2: :x :P :oops: :cry: :evil: :roll: :wink: :!: :?: :idea: :arrow: :| :mrgreen:
View more smilies

BBCode is ON
[img] is ON
[url] is ON
Smilies are ON

Topic review
   

Expand view Topic review: APOD: Despina, Moon of Neptune (2014 Jan 16)

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Nitpicker » Wed Feb 26, 2014 11:44 pm

Chris Peterson wrote:
Nitpicker wrote:A bit like trying to estimate the length of a bus when it is about to run you over. It is simply the wrong vantage point to observe the elliptical orbit shape.
And yet, that's what orbital analysis is all about. You take the coordinates of an object observed at several locations, which typically looks very close to a line segment, and fit them to the only possible elliptical orbit.
Indeed, but my point was you don't typically observe the ellipse -- you derive it from your observations and calculations.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Chris Peterson » Wed Feb 26, 2014 11:39 pm

Nitpicker wrote:A bit like trying to estimate the length of a bus when it is about to run you over. It is simply the wrong vantage point to observe the elliptical orbit shape.
And yet, that's what orbital analysis is all about. You take the coordinates of an object observed at several locations, which typically looks very close to a line segment, and fit them to the only possible elliptical orbit.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Nitpicker » Wed Feb 26, 2014 11:33 pm

A bit like trying to estimate the length of a bus when it is about to run you over. It is simply the wrong vantage point to observe the elliptical orbit shape.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by geckzilla » Wed Feb 26, 2014 10:31 pm

Gr8Glaroon wrote:One thing puzzles me about this image. If it's a time-lapse photograph, that means it includes different pictures taken while Despina is at different points along its orbit around Neptune. Its orbit is elliptical, probably close to circular, which means that its path along its orbit has a curvature to it. So why does the time-lapse photograph show the moon Despina traveling along a straight trajectory? That trajectory should follow more-or-less the same close-to-circular path as the surface of the planet below it, since its orbit would tend to keep it at about the same distance from the surface of the planet. Yet the time-lapse photography shows the moon Despina following almost a perfect straight-line path. I don't understand.

Ron
Optical illusion. The moon's path is not straight at all. It just looks straight compared to the curvature of Neptune's limb in the background. And, anyway, the limited perspective can really throw you off. Even if you draw a straight line to compare it to, Despina looks like it's going to crash into Neptune but we know that's not true. If you could reach into the image and rotate it around as a three dimensional projection then it would be simple to understand but all we have is a flat image.
despina_line.jpg

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Gr8Glaroon » Wed Feb 26, 2014 10:20 pm

One thing puzzles me about this image. If it's a time-lapse photograph, that means it includes different pictures taken while Despina is at different points along its orbit around Neptune. Its orbit is elliptical, probably close to circular, which means that its path along its orbit has a curvature to it. So why does the time-lapse photograph show the moon Despina traveling along a straight trajectory? That trajectory should follow more-or-less the same close-to-circular path as the surface of the planet below it, since its orbit would tend to keep it at about the same distance from the surface of the planet. Yet the time-lapse photography shows the moon Despina following almost a perfect straight-line path. I don't understand.

Ron

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Nitpicker » Fri Jan 17, 2014 3:01 am

starsurfer wrote:
Boomer12k wrote:Not just the "most distant gas planet"....but now days....the most distant Planet....

But this image combination shows...you can still discover something new....

:---[===] *
PLUTO LIVES! :D
... as a beloved Dwarf Planet, with relatively brief periods closer to the Sun than Neptune, the most distant Planet in the Solar System. :p:

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Anthony Barreiro » Fri Jan 17, 2014 12:50 am

Chris Peterson wrote:
eltodesukane wrote:Not much has happen since 1989 in the exploration of the outer solar system. Kind of sad.
(Voyager 2's closest approach to Neptune occurred on August 25, 1989.)
I wouldn't discount Cassini-Huygens, which has been intensively studying the Saturn system for the last decade, and continues to do so. And we're just over a year from New Horizons passing through the Pluto system. And both Cassini and New Horizons encountered Jupiter and returned data from there.
And Juno is on her way to spy on the hijinks Jupiter is getting up to under cover of clouds.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by geckzilla » Thu Jan 16, 2014 8:41 pm

bactame wrote:Well walking around would be unsafe and the bigger the stone the more unsafe. Bring a milk pail on a stick and stick that out there. A robot-ish thing might do as well but a pail on a stick would be more cost effective.
Even a robot can't survive being pelted by diamonds moving at 1000 miles per hour.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by neufer » Thu Jan 16, 2014 8:22 pm

geckzilla wrote:
bactame wrote:
If it is raining diamonds because of the high [sic] temperature and low [sic] pressures
expected then an orbiter could catch such diamonds as may be available.
This seems wildly unsafe... not unlike walking out during a hail storm or a tornado.
  • Besides...in the end some old lady is just going to drop "the ice" back into Neptune anyway.
http://en.wikipedia.org/wiki/Heart_of_the_Ocean wrote:
<<The Heart of the Ocean (also known as Le Cœur de la Mer) is the name of a fictional blue diamond featured prominently in the 1997 film Titanic. In the film, treasure hunter Brock Lovett (Bill Paxton) searches for a necklace, which he believes lies within the wreck of the RMS Titanic. His hunch seems to be confirmed when his team salvages a drawing, dated on the day the Titanic struck an iceberg, in which a nude woman is portrayed wearing only the necklace. The necklace was fashioned from a large blue diamond worn by Louis XVI. Shortly after his execution in 1793, the diamond disappeared and was recut into a heart-like shape, known as "The Heart of the Ocean".

The woman in the picture, Rose DeWitt Bukater (Gloria Stuart when old and Kate Winslet when young), contacts Lovett and is flown out to his recovery ship, where she relates her story of her voyage. Rose wore the necklace when Jack Dawson (Leonardo DiCaprio) drew her – the very drawing that Lovett later salvaged. At the end of the film, Rose walks alone to the stern of the salvage ship and lets the necklace fall from her hand and into the water above the Titanic's wreck site.>>
http://news.discovery.com/space/alien-life-exoplanets/diamond-oceans-jupiter-uranus.htm wrote:
Diamond Oceans Possible on Uranus, Neptune
by Eric Bland, Discovery, Jan 15, 2010

<<Oceans of liquid diamond, filled with solid diamond icebergs, could be floating on Neptune and Uranus, according to a recent article in the journal Nature Physics. The research, based on the first detailed measurements of the melting point of diamond, found diamond behaves like water during freezing and melting, with solid forms floating atop liquid forms. The surprising revelation gives scientists a new understanding about diamonds and some of the most distant planets in our solar system. "Diamond is a relatively common material on Earth, but its melting point has never been measured," said J. H. Eggert of Lawrence Livermore National Laboratory in Livermore, California. "You can't just raise the temperature and have it melt, you have to also go to high pressures, which makes it very difficult to measure the temperature."

Diamond is an incredibly hard material. That alone makes it difficult to melt. But diamond has another quality that makes it even harder to measure its melting point. Diamond doesn't like to stay diamond when it gets hot. When diamond is heated to extreme temperatures it physically changes, from diamond to graphite. The graphite, and not the diamond, then melts into a liquid. The trick for the scientists was to heat the diamond up while simultaneously stopping it from transforming into graphite.

Eggert and his colleagues took a small, natural, clear diamond, about a tenth of a carat by weight and half a millimeter thick, and blasted it with lasers at ultrahigh pressures like those found on gas giants like Neptune and Uranus. The scientists liquefied the diamond at pressures 40 million times greater than what a person feels when standing at sea level on Earth. From there they slowly reduced the temperature and pressure.

When the pressure dropped to about 11 million times the atmospheric pressure at sea level on Earth and the temperature dropped to about 50,000 degrees, solid chunks of diamond began to appear. The pressure kept dropping, but the temperature of the diamond remained the same, with more and more chunks of diamond forming. Then the diamond did something unexpected. The chunks of diamond didn't sink. They floated. Microscopic diamond ice burgs floated in a tiny sea of liquid diamond. The diamond was behaving like water. With most materials, the solid state is more dense than the liquid state. Water is an exception to that rule; when water freezes, the resulting ice is actually less dense than the surrounding water, which is why the ice floats and fish can survive a Minnesota winter.

An ocean of diamond could help explain the orientation of Uranus' and Neptune's magnetic field as well, said Eggert. Roughly speaking, the Earth's magnetic poles match up with the geographic poles. The magnetic and geographic poles on Uranus and Neptune do not match up; in fact, they can be up to 60 degrees off of the north-south axis. If Earth's magnetic field were that far off it would place the magnetic north pole in Texas instead of off a Canadian island. A swirling ocean of liquid diamond could be responsible for the discrepancy. Up to 10 percent of Uranus and Neptune is estimated to be made from carbon. A huge ocean of liquid diamond in the right place could deflect or tilt the magnetic field out of alignment with the rotation of the planet.

The idea that there are oceans of liquid diamond on Neptune and Uranus is not a new idea, said Tom Duffy, a planetary scientist at Princeton University. The new Nature Physics article makes diamond oceans "look more and more plausible," said Duffy. More research on the composition of Neptune and Uranus is needed before a truly definitive conclusion can be made, however, and this kind of research is very difficult to conduct. Scientists can either send spacecraft to these planets, or they can try to simulate the conditions on Earth. Both options require years of preparation, expensive equipment, and are subject to some of the toughest environments in the universe.>>

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by BMAONE23 » Thu Jan 16, 2014 8:16 pm

Despina is the third of Neptune's known satellites:

orbit: 52,600 km from Neptune
diameter: 148 km
mass: ?Despina was a nymph, the daughter of Poseidon (Neptune) and Demeter.

Discovered in 1989 by Voyager 2.
Image
This image of Despina was taken by V-Ger2 in 1989

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Chris Peterson » Thu Jan 16, 2014 8:02 pm

eltodesukane wrote:Not much has happen since 1989 in the exploration of the outer solar system. Kind of sad.
(Voyager 2's closest approach to Neptune occurred on August 25, 1989.)
I wouldn't discount Cassini-Huygens, which has been intensively studying the Saturn system for the last decade, and continues to do so. And we're just over a year from New Horizons passing through the Pluto system. And both Cassini and New Horizons encountered Jupiter and returned data from there.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by bactame » Thu Jan 16, 2014 7:58 pm

"Geckzilla wrote:
This seems wildly unsafe... not unlike walking out during a hail storm or a tornado."
Well walking around would be unsafe and the bigger the stone the more unsafe. Bring a milk pail on a stick and stick that out there. A robot-ish thing might do as well but a pail on a stick would be more cost effective.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by eltodesukane » Thu Jan 16, 2014 7:53 pm

Not much has happen since 1977 (37 years ago) in the exploration of the outer solar system. Kind of sad.
(The Voyager 2 probe was launched on August 20, 1977)
(Voyager 2's closest approach to Jupiter occurred on July 9, 1979)
(Voyager 2's closest approach to Saturn occurred on August 26, 1981)
(Voyager 2's closest approach to Uranus occurred on January 24, 1986)
(Voyager 2's closest approach to Neptune occurred on August 25, 1989.)

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by geckzilla » Thu Jan 16, 2014 7:23 pm

bactame wrote:If it is raining diamonds because of the high temperature and and low pressures expected then an orbiter could catch such diamonds as may be available.
This seems wildly unsafe... not unlike walking out during a hail storm or a tornado.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by bactame » Thu Jan 16, 2014 7:08 pm

There was some discussion recently about getting rich by collecting olivine crystals from a stellar nebula but this Neptune story tops that source of Wealth. Open the link at "Neptune's blue cloud tops" and go to that older APOD page. On that page of 22 September, 2002 open the link at "Speculation" and read the article there called "Its raining diamonds on Neptune"

If it is raining diamonds because of the high temperature and and low pressures expected then an orbiter could catch such diamonds as may be available. I have seen engineers making industrial diamonds and some of those guys can make them in very large sizes. I saw one that fit snugly into a 2 pound coffee can, the old style one Hills Brothers cans. These particular engineers were making large diamonds for those mining machines. They were making the large diamonds for the cutting heads on those machines and the angles on the facets were related to the hardness of rocks in the mine. They used furnaces to make those diamonds and they ran the furnace for days and days to get these gigantic items in inert gas atmospheres.

At any rate Neptune's atmosphere in Hydrogen & Helium which might be inert as well so the size of the diamonds would be similar if descent times could be controlled. In any case Neptune is much closer than the Orion Nebula. At any rate you could catch the diamonds in a flyby.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by retrogalax » Thu Jan 16, 2014 7:05 pm

This one is really tiny.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by neufer » Thu Jan 16, 2014 6:29 pm

owlice wrote:
Nitpicker wrote:
I know this is an APOD repeat from 2009, but I happened to read that blog article
-- http://www.planetary.org/blogs/emily-la ... /2035.html --
quite independently a few months ago. It is a great image and a great story.
Nitpicker, you're right; that is a great story! I had not read it until prompted to by your post.
  • Hamlet, Prince of Denmark Act 1, Scene 5
HAMLET: There are more things in heaven and earth, Horatio,
  • Than are dreamt of in your philosophy class.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by geckzilla » Thu Jan 16, 2014 6:18 pm

:shock: Oi, yeah, my only nom de guerre is geckzilla. Ted seems to stick to the planetary data which I have a slight aversion to. Ted's blog is a little difficult to browse but you can see more of his work there.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by owlice » Thu Jan 16, 2014 5:49 pm

This is a lovely image, as others have pointed out, and how great for TED STRYK to make this beautiful and interesting find! Congratulations!!!!

Nitpicker, you're right; that is a great story! I had not read it until prompted to by your post.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by owlice » Thu Jan 16, 2014 5:41 pm

No. The two images and the two finds have nothing to do with one another.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Frenchie » Thu Jan 16, 2014 5:33 pm

Ann wrote:It's a lovely picture (I'll read the story later)!

And don't we know, here at Starship Asterisk*, that amateur image processors can discover something important that the rest of the astronomical community was completely unaware of.

Way to go, geckzilla! :-D :clap:
geckzilla wrote:Hehe, I wouldn't say it's important but it was fun to find. It could be an extra point in a data plot one day. Digging through archives can be personally rewarding even if you find nothing new at all.
Is Ted Stryk a nom de guerre for Judy Schmidt?

Despina, the unnameable "Mistress of the House"

by neufer » Thu Jan 16, 2014 4:49 pm

http://en.wikipedia.org/wiki/Despina_%28moon%29 wrote:
<<Despina (Latin: Despœna,; Greek: Δέσποινα), also known as Neptune V, is the third closest inner satellite of Neptune. Despina is irregularly shaped and shows no sign of any geological modification. It is likely that it is a rubble pile re-accreted from fragments of Neptune's original satellites, which were smashed up by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit. Despina's orbit lies close to but outside of the orbit of Thalassa and just inside the Le Verrier ring. As it is also below Neptune's synchronous orbit radius, it is slowly spiraling inward due to tidal deceleration and may eventually impact Neptune's atmosphere, or break up into a planetary ring upon passing its Roche limit due to tidal stretching.>>
http://en.wikipedia.org/wiki/Despoina wrote:
Click to play embedded YouTube video.
<<In Greek mythology, Despoina, Despoena or Despoine, was the daughter of Demeter and Poseidon and sister of Arion. Pausanias spoke of Demeter as having two daughters; Kore being born first, then later Despoina, with Zeus being the father of Kore, and Poseidon as the father of Despoina. Pausanias made it clear that Kore is Persephone, though he wouldn't reveal Despoina's proper name.

In the primitive myth, Poseidon saw Demeter, the Earth mother and desired her. To avoid him, she took her archaic form of a mare, but he took the form of a stallion and mated with her. From this union Demeter bore a daughter Despoina and a fabulous horse Arion (Ἀρείων). Due to her anger at this turn of events, Demeter took on the epithet Erinys, or raging.

The word Despoina (Δέσποινα) "mistress" is derived from the Mycenean Greek *des-potnia which is interpreted as "lady or mistress of the house." The masculine form is despotes (Δεσπότης), "master of the household. Related words are the Mycenean Greek potnia and Posedao (Poseidon), which were inherited in classical Greece with the same meaning. Demeter is probably a relative word interpreted as "mother of the house."

Despoina was the goddess of mysteries of Arcadian cults worshipped under the title Despoina, "the mistress" alongside with her mother Demeter, one of the goddesses of the Eleusinian mysteries. Her real name could not be revealed to anyone except those initiated to her mysteries. Despoina became worshipped in a sanctuary at Lycosura west to the town of Megalopolis. Despoina was later conflated with Persephone (i.e., Kore). First in that place there was a temple of Artemis Hegemone (the leader) with a bronze image (apparently Hecate). From this place there was an entrance to the sacred enclosure of Despoine. In the portico there was a tablet with the inscriptions of the mysteries. In front of the temple there was an altar to Demeter and another to Despoine, after which was one of the Great Mother. Demeter carried a torch in her right hand and her other hand was laid upon Despoine. By the image of Despoine stood Anytos, one of the Titans(; the Arcadians believed that Despoine was brought up by Anytos). Besides the temple there was the hall where the Arcadians celebrated the mysteries and beyond it a grove sacred to Despoine and altars of Poseidon Hippios (horse) and other gods too.

In the mysteries Demeter was a second goddess under her daughter, the unnameable "Despoina". The two goddesses had close connections with the rivers and the springs. They were related with the god of the rivers and the springs Poseidon and especially with Artemis, who was the first nymph. Despoina was later conflated with Kore (Persephone), the goddess of the Eleusinian mysteries in a life-death-rebirth cycle.

At the time of Pausanias visit in the 2nd century BE, the sculptures would have been three hundred or more years old. In the 2nd century CE, a statue of the emperor Hadrian was dedicated in the temple. Coins from Megalopolis, from the Severan period in the early 3rd century appear to depict the cult statue group.

In the Mass Effect 3 video game, 2181 Despoina is the planet occupied by a powerful ancient mind-controlling species.

In the 1963 science fiction novel "Sign of the Labrys" by Margaret St. Clair, one of the main characters is a witch named Despoina.>>

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Psnarf » Thu Jan 16, 2014 4:14 pm

Thank you for urging me to get smarter on Neptune. I did not know that Neptune has six rings. There are clumps of dust in those rings that make them appear to be arcs. Perhaps those rings are in the early stages of formation? Maybe someday the rings will have a more uniform density. I've given up memorizing the names of moons in the Solar System. Neptune has 14, 13 named after characters in the ancient Greek pantheon in myths about Poseidon. Poseidon's sister, Demeter, turned into a horse to hide from Poseidon and his amorous advances. Unbaffled, Poseidon turned himself into a stallion [details deleted for a polite audience], and Despina was one of the two children resulting from those goings-on. I don't know how those ancient Greeks got so stoned, but, I mean, turning a group of stars that appears to me as a giant dubya into the partially clothed goddess Cassiopeia takes more imagination than I can muster. The myths do not elucidate upon the subject of incest-induced birth defects or the mental prowess of Despina, but in-breeding prevalent in the early British monarchy is a digression for another forum.

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by biddie67 » Thu Jan 16, 2014 3:51 pm

Great find !!!

(( and beautiful .... ))

Re: APOD: Despina, Moon of Neptune (2014 Jan 16)

by Tszabeau » Thu Jan 16, 2014 1:44 pm

"Did it take long to find me..."

Top