Hubble Photo of Sedna Suprises Astronomers 342
waynegoode writes "Soon after the announcement of the discovery of Sedna, the solar system's furthest object and planet wanna-be, the Hubble Space Telescope was pointed at it to answer some of the many questions its discovery generated. The photos were released today and are surprising for what they don't show--a moon. Astronomers were certain it had a moon because of its slow rotation. "I'm completely baffled at the absence of a moon," says Michael Brown, Sedna's discoverer. Story and photo at Universe Today, hubblesite and NASA press release."
Why am I not surprised :-) (Score:3, Insightful)
The planet that's not a planet has a moon that's not there!
Perhaps it used to rotate fast, but got hit by some other asteroid in an opposing fashion, so now it rotates slowly ? Space is big (!) so this is unlikely, but if Sedna is not too far from the Kuiper belt, perhaps it's less unlikely than one might expect...
Simon
Re:Why am I not surprised :-) (Score:4, Funny)
Things can get messy out there in the kupier belt. Its not a place where you want to be alone late at night.
Re:Why am I not surprised :-) (Score:5, Informative)
The object is not there, though there is a very small chance it might have been behind Sedna or transiting in front of it, so that it could not be seen separately from Sedna itself in the Hubble images.
Granted the likelyhood of this isn't great, but I think it is a lot more probable than the explanations suggested in the parent posts.
Re:Why am I not surprised :-) (Score:2, Informative)
Re:Why am I not surprised :-) (Score:2, Funny)
In the outskirts of the solar system it's always night...
The inner system never sleeps. The oute system never wakes.
Re:Why am I not surprised :-) (Score:3, Funny)
Until the stars are right... Somewhere out there is Yuggoth.
Mercury never sleeps? (Score:5, Informative)
The inner system never sleeps. The outer system never wakes.
Sounds deep, but unfortunately, it is incorrect. Mercury (it doesn't get more "inner" than that) "sleeps" a great deal. Due to its eccentric orbit and bizzarrely-coordinated orbital period and rotational period, a single day on Mercury lasts as long as two of its years! That is to say, its rotational period is exactly two-thirds of its orbital period, meaning "nighttime" on Mercury lasts several Earth months. That's a lot of "sleeping" for a planet in the inner system which, according to you, never sleeps.
Incidentally, while we generally presume Mercury to be a very hot place (and it is, during the day), the temperature on side of the planet that is in nighttime can drop to -150 degrees Celcius.
Re:Why am I not surprised :-) (Score:5, Insightful)
Re:Why am I not surprised :-) (Score:2, Funny)
Re:Why am I not surprised :-) (Score:3, Funny)
Re:Why am I not surprised :-) (Score:2)
Re:Why am I not surprised :-) (Score:4, Interesting)
Re:Why am I not surprised :-) (Score:3, Insightful)
Re:Why am I not surprised :-) (Score:2)
My, have we forgotten our Theory of Improbability already? Well, I guess that's ok, then. Me, I'm still working on my Improbability Drive, and when it's done, I'm getting off this rock for good. ;)
Re:Why am I not surprised :-) (Score:5, Interesting)
The collision theory is extraordinarily unlikely, although of course in a sense possible. A few more likely scenarios strike me though.
Remember that Sedna itself is so small the Hubble can't resolve it. So Sednas companion could be quite tiny and still large enough to affect it. If it has a very small companion with a very low reflectivity, would it be surprising if Hubble didn't pick it up immediately? I'm not an astronomer, and there may be something I'm missing, but that seems quite plausible to me.
It also seems possible that it was part of a binary system earlier and lost its companion, or that it's rotation rate was affected by one or more near misses out in the kuiper belt. We don't know the history of this object at all, we barely even know it exists. It is cool that an initial prediction seems to be a failure here, because that indicates a potential to learn new things, but at the same time it's hardly surprising given how small and far away the thing is and how difficult this makes it to detect and measure.
Why (sh)wouldn't it rotate so slowly? (Score:3, Insightful)
Any enlightened thinkers care to explain?
Re:Why am I not surprised :-) (Score:3, Interesting)
or perhaps the moon just has a low albedo. Maybe we can rename the moon "Krylon matte black"
got hit by some other asteroid (Score:2)
When... (Score:4, Funny)
I think budget issues will determine... (Score:3, Informative)
unmanned to Titan Jan 2005 (Score:2)
Re:unmanned to Titan Jan 2005 (Score:2)
That's no moon (Score:3, Funny)
Re:When... (Score:2)
seriously, chaps. you don't see this kind of stupid childishness from conservatives. every time someone makes another cheap, unfunny WMD joke, or fucking cheerlead for peace, it makes me ashamed to be anti-gwb.
I suppose I imagined all of those cheap blow-job jokes from conservatives during the Clinton Administration?
Re:When... (Score:5, Insightful)
What class. Bodies of US soldiers (which we're not allowed to see) being returned by the dozen, and the guy is laughing at his deception which sent the troops there in the first place.
Re:When... (Score:5, Insightful)
Turns out he didn't have wmds therefore couldn't disarm, therefore the invasion of Iraq was a fait accompli.
A little vignette which serves to illustrate the problem with the USA. In Baghdad there is a Burger King. Iraqis aren't allowed near it, it's in a 'secure zone'. Burgers are flown in from the USA. The staff have been flown in from Nepal, rather than staff it with Iraqis. There is a real disconnect between the US troops and Iraqi peoples that is only making it harder to win hearts and minds.
That's no absence of a moon ... (Score:5, Funny)
It's an absence of a space station!
Sedna's Slow Spin (Score:3, Insightful)
it has to be aliens screwing with us (Score:4, Funny)
Maybe they call it.... (Score:2, Offtopic)
news (Score:5, Funny)
the sun rose so it can't be that....
water is still wet...
i'm baffled.
Re:news (Score:5, Funny)
No it isn't [slashdot.org].
Re:news (Score:2)
Rare Event (Score:2, Funny)
Not an expert (Score:5, Interesting)
Re:Not an expert (Score:5, Informative)
The other issue is that the planet can only occult the moon if the moon's orbit is edge-on to the Earth. That's true of many moons - consider the Galilean satellites of Jupiter, which eclipse and are eclipsed by their primary on a regular basis - but is very unlikely to be true of such an eccentric object as Sedna. Objects that far out don't adhere well to the ecliptic - they tend to go their own way :-)
Re:Not an expert (Score:3, Informative)
Assuming its orbit is in the ecliptic plane. This is not a good assumption from Neptun onwards.
A moon? (Score:4, Interesting)
Now I am wondering if our Moon has another moon orbiting around
Re:A moon? (Score:2, Informative)
Pluto is comparable in size with our own moon, and it has a moon of its own.
Asteroid Ida has a moon. Ida is about 56 by 24 by 21 kilometers in size.
Having a moon has nothing to do with size.
Re:A moon? (Score:4, Funny)
Surely that's "Charon"?
And don't call me Shirly
Paul
Re:A moon? (Score:2, Interesting)
PICTURES of a MOON with a MOON (Score:5, Informative)
Dactyl is about 0.75 x 0.8 x 1.0 miles in size [solarviews.com]. Imagine that!! Imagine sitting on Dactyl and orbiting Ida. Now, I'm not sure if a rock of 1 mile in diameter can even hold you down.
Does anyone know how to calculate your weight on Dactyl? Size listed above and it's probably 2.2 - 2.9 grams per cubic centimeter.
Re:PICTURES of a MOON with a MOON (Score:2, Funny)
Re:PICTURES of a MOON with a MOON (Score:2)
OMG! Ida looks like a mummy sarcofagus! It must have been put there by the the same people who built the pyramids and the cydonia structures.
Actually, it's Lore.
Re:PICTURES of a MOON with a MOON (Score:5, Informative)
The acceleration due to gravity is Gm/r^2. r, in this case, is the surface of Dactyl, 750m. That gives 0.5x10^-3 m/s^2, or 0.005% of an Earth gee.
That is, of course, assuming I've managed to do all my arithmetic correctly...
(Pity Slashdot doesn't support super, or I could make the above look much cleaner. MathML would be nice, too...)
Dactyl escape velocity (Score:3, Interesting)
Colon Powell releases Hubble photos in UN forum. (Score:4, Funny)
It is unclear how Saddam Hussein delivered and stockpiled the weapons on Sedna, but the blury photographic proof shows beyond a shadow of a doubt that the administration was in the Right from the beginning. NASA was unavailable for comment.
Re:Colon Powell releases Hubble photos in UN forum (Score:2)
- Donald Rumsfeld.
Re:Colon Powell releases Hubble photos in UN forum (Score:2)
The absence of evidence is not evidence of absence"
- Donald Rumsfeld.
So Doland Rumsfeld thinks there might be a Moon there after all ??
Re:Colon Powell releases Hubble photos in UN forum (Score:2)
"The absence of evidence is not evidence of absence"
I'd like to see you prove you don't have any dual-use technology. Bold assertion is not sufficient reason to go to war.
Re:Colon Powell releases Hubble photos in UN forum (Score:2, Insightful)
You know, in the past, most people have waited until the other guys stopped killing them before claiming a victory.
Maybe someone should go out there and tell all those Iraqi irregulars that you guys have WON, and so could they please stop blowing shit up?
Re:Colon Powell releases Hubble photos in UN forum (Score:2)
The successful invasion of a country and the overthrow of its government is not the same as winning a war.
Re:Colon Powell releases Hubble photos in UN forum (Score:3, Insightful)
That's a new one. The way I always heard it was that Iraq was fighting a war against Iran, who was our enemy. And how do you think the Iraqis got MiG jets and Russian tanks? The russians didn't like the Iranians either! It wasn't the Russians we were trying to fight, it was the Iranians.
Becuase it was an election year, and he
No, no, it has a moon! (Score:2, Funny)
When Sedna's lu--r object has found a new name, and shaken off Microsoft's legal team, it will reappear.
Except in Benelux.
Lu-dash? (Score:2)
Not so surprising... (Score:5, Interesting)
So if the so-called planet is the size of one pixel, how do they expect to see a smaller moon?
And, yes, I'm quite aware of techniques such as extrapolations, anti-aliasing etc. which *may* help extract a smaller-than-1-pixel object using a series of 35 pictures, but I'd speculate that NASA's assertion that Sedna does not have a moon is premature.
Re:Not so surprising... (Score:4, Insightful)
So they are looking for a darker blip next to the gray blip that is sedna.
Re:Not so surprising... (Score:2, Informative)
You'd expect its moon to be one pixel, with RGB (50,50,50) maybe.
How someone using the buzzwords "extrapolations" and "anti-aliasing" can miss this would be a better question.
maybe it had a moon (Score:4, Interesting)
The slow rotation may account for a moon or child body which was able to escape the rotational cycle, or was flung off into space during its creation. Which is FAR FAR more likely given its distance from the sun
The other reason maybe attributed to the fact that it is beyond the astroid belt, and is the furthest satellite we've discovered yet. Although it is a small target, it maybe the solar system's first line of defense (eg a riot shield) although not a good one. That could account for both slow/erratic rotation or a missing orbital body.
space.com (Score:5, Informative)
Small info:
* Sedna is about three-fourths the size of Pluto.
* It takes 10,000 years to orbit the Sun.
* Sedna spins on its axis once every 20 Earth-days.
So, in Sedna years, I am only... (Score:2)
> * Sedna spins on its axis once every 20 Earth-days.
So, in Sedna years, I am only 0.0273 years (498 days ) old! That explains a few things...
Re:space.com (Score:5, Funny)
Re:space.com (Score:2)
Resolution (Score:3, Insightful)
This surprised me a lot. Hubble can take pretty (for me as a non-astronomer) pictures of objects far away and in the past (wasn't only recently something so old that it is almost the beginning of the universe?), and yet it can't take a picture of something within our system larger than a pixel... Anyone with some knowledge care to elaborate on that?
Re:Resolution (Score:3, Informative)
According to the Google calculator = (1/8,000,000) radians = 0.0257831008 arc seconds.
The field of view in the "pretty pictures of objects far away" is simply much larger than 0.025 arc seconds.
Re:Resolution (Score:5, Interesting)
Now you may start to get a sense of just how mind-freakingly big some interstellar objects are. This logarithmic maps of the universe [princeton.edu] should help put things in perspective. Once you've got the image, start from the very bottom and work your way up. And keep repeating to yourself, "another order of magnitude... and another order of magnitude... and another..."
Re:Resolution (Score:3, Funny)
-Colin [colingregorypalmer.net]
+5 Mind boogling (Score:2)
Re:Resolution (Score:5, Informative)
Sedna is Really small and Really far away.
The rest of the universe is Really Really far away, but is also Really, Really Big.
Hubble's lenses, when imaging, take into account these Really's so that when you cancel out the Really's, Sedna ends up small and the rest of the universe ends up Big in hubble pictures.
No moon, no Mars. (Score:5, Funny)
Quality? (Score:2, Insightful)
Re:Quality? (Score:2, Insightful)
Re:Quality? (Score:2, Informative)
Re:Quality? (Score:5, Informative)
NaSa are wonderful at using Hubble to produce pretty publicity images. I'm not saying that the images of nebulae etc. are not without scientific justification, only that NaSa are very good at presenting them to the public.
These images are more typical of the data taken by Hubble on a day-to-day basis; single filter images (presented in black and white) of faint objects pushing down close to the detection limit of the instruments.
Re:Quality? (Score:2)
Re:Quality? (Score:5, Informative)
The electronic detectors (CCDs) on HST, as on virtually all professional telescopes, are inherently monochrome detectors. During an exposure, the detector is behind one of several filters. There are filters that pass UV light, blue light, green light, red light, infrared light, etc. In many cases, the same bit of sky is observed in multiple filters, one after the other. If these happen to be red, green, and blue filters, you can put the three images in the red, green, and blue channels of a color image, and get something that's approximately true color. The filters are not designed to exactly mimic the human eye's color response; that's not an important concern from a scientific standpoint. If some other combination of three filters is used, they can still be placed in the RGB channels of an image, but the result will be a false-color image. That doesn't mean the color information is meaningless; parts of the nebula that look "blue" in the image probably have something physically different happening than parts that look "red."
Many people have an unrealistic expectation that colors in astronomical images should be exactly correct. That's a hard thing to nail down. As I mentioned above, the filters are not designed for human-vision color fidelity, since that's not relevant to the scientific goals at hand. Also, if you look at a nebula with your eye, even through a very large telescope, you vision will be dominated by the color-insensitive rods, and the nebula will appear quite washed-out. So do you want the publicity pictures to mimic this shortcoming of human vision (that we don't see much color in faint things)?
Back to the topic of the CCDs being monochrome detectors: This is true of the CCD or CMOS detectors in consumer digital cameras, too. But instead of putting the whole detector behind a colored filter, each pixel on the detector is behind a tiny red, green, or blue filter. Thus, each detector pixel is still only recording one of the three colors of light. (The new Foveon chips are an exception to this rule.)
that isn't the planet in the picture ... (Score:5, Funny)
(the planet is hiding behind it)....
Moon is not the issue (Score:2, Funny)
No more Hubble (Score:4, Funny)
Dr.Mike Brown gives four possible explanations.. (Score:5, Informative)
We can think of 4 possibilities for why we do not see a moon around Sedna.
Re:Dr.Mike Brown gives four possible explanations. (Score:2, Informative)
BTW, his site has more information on Sedna [caltech.edu].
Re:Dr.Mike Brown gives four possible explanations. (Score:5, Insightful)
Well duh (Score:2, Funny)
Sure, things were going great till we discovered her... Sedna had convinced the moon he was all that and a bag of potatoes. But as soon as the moon heard the word on the street that her man wasn't even big enough to be considered a planet....
Its just like the saying goes... in some relationships, size *does* matter.
The Truth About Sedna (Score:2, Funny)
And this demonstrates! (Score:3, Funny)
oh wait.
Never mind.
See more Sedna [savehubble.org]
This is what happens.... (Score:3, Funny)
Has someone saved the animals yet? Nibbler?
those are nice big.... pixels (Score:3, Funny)
Astrological significance? (Score:3, Interesting)
Offtopic? Only if you've never read a horoscope.
Crappy picture (Score:2)
Re:Crappy picture (Score:2, Insightful)
1986 Oldsmobile Cutlass Supreme (Score:4, Funny)
I immediately pictured astronomers scratching their heads over Hubble photos of my former '86 Oldsmobile Cutlass Supreme, named "Plum" (for the color, and short for "Plum Tuckered Out")... zooming through the far reaches of space.
So it DID go to car heaven!!
Suprise? (Score:2)
Maybe it's just shy (Score:2)
Save Hubble (Score:4, Informative)
Re:It may sound silly... (Score:3, Interesting)
Re:Political Correctness even infects Astronomy! (Score:5, Informative)
Oh, and Inuits would be offended if you call them Red Indian. Any native Americans would, in fact, but Inuits are not even 'red'.
Re:Political Correctness even infects Astronomy! (Score:2)
Re:Political Correctness even infects Astronomy! (Score:3, Funny)
You've obviously never heard of the planet Vulcan... duh.
Re:Marvel!!!! (Score:2, Funny)
Bad moon? (Score:2)
I always thought it was "there's a bathroom on the right".