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New Galactic Neighbor
Posted by
samzenpus
on Wed Jan 11, 2006 08:55 PM
from the there-goes-the-neighborhood dept.
from the there-goes-the-neighborhood dept.
Dan Yocum writes "The Sloan Digital Sky Survey reveals a new Milky Way neighbor: a galaxy so big we couldn't see it before. A huge but very faint structure, containing hundreds of thousands of stars spread over an area nearly 5,000 times the size of a full moon, has been discovered and mapped by astronomers of the Sloan Digital Sky Survey."
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So (Score:5, Funny)
Re:So (Score:3, Funny)
3 blind scientists
How do they define a galaxy? (Score:3, Interesting)
Re:How do they define a galaxy? (Score:5, Funny)
It becomes Congress?
What happens if a black hole eats...? (Score:5, Funny)
Re:How do they define a galaxy? (Score:5, Insightful)
Re:How do they define a galaxy? (Score:5, Interesting)
Yes, this is offtopic, but what is really wild is that they simulated that in 1994 on a Cray C90, which has a floating point speed of 16 gigaflops. Back here in 2006: the Playstation 3, a TOY, has a floating point speed of 2 teraflops.
Not very long ago... (Score:5, Funny)
Could this be... (Score:5, Interesting)
Re:Could this be... (Score:4, Informative)
*in warbly voice* (Score:4, Funny)
5000 times the size of a full moon? (Score:4, Informative)
Interesting wording.
So that must mean 5000 full moons in the sky?
Moon = 1800 arc seconds
or 1800/60 = 30 arc minutes.
or 30/60 =
So what is that in degree of sky?
A fist at arms length is roughly 10 degrees.
Re:5000 times the size of a full moon? (Score:5, Funny)
FTFA: nearly 5,000 times the size of a full moon
So naturally it is 5000*0.5 = 2500 degrees, silly!
Re:5000 times the size of a full moon? (Score:5, Informative)
The measurements you offered for the degrees of the moon concerns of course only one dimesnion of the moon.
Now, suppose we assume that that galaxy is roughly squarish, we just need to take the square root of 5000 and we get roughly 70 which means that in the sky the galaxy is 70 times bigger than the moon in any one dimension (lets say width).
Therefore, assuming your other calculations are correct, then the galaxy is about 70x0.5= 35 degrees in the sky. Which is pretty big if you think about it.
Some SDSS info (Score:5, Informative)
Some very clever optics (designed by James Gunn) went into the telescope. Normal telescopes do not produce the large field of view required. There were existing specialized telescopes which did (Schmidt cameras) but they have the imaging plane in the wrong place.
The main camera uses 30 2k x 2k CCDs, cooled by liquid nitrogen. At the time (early '90s) these cost on the order of $200k per chip.
The camera works in "drift scan" mode: the telescope moves such that the images of the stars drift along the columns of detectors in the CCDs. The packets of charge are shifted along the CCDs at the same rate - so instead of producing distinct individual frames, it continuously outputs data along an ever-lengthening strip along the sky. As I recall, the data rate is about 8Mbyte/s.
The camera spends rather more time on spectroscopy than imaging. (The imaging is primarily about selecting targets for the spectroscopy.) The spectrograph does 640 objects at a time. A computer-drilled plate is (manually) plugged with fibre optic cables in the right positions for that field of sky.
like looking at the milky way through 3d glasses (Score:5, Funny)
I wonder where he got 3d glasses that make stuff look 3d in real life? I could use some of them to stop walking into walls so much!
Appearance from outside (Score:4, Insightful)
Well, now we know. Little did we know that we knew all along.
Very cool! (Score:4, Funny)
Re:Wrong priorities... (Score:5, Informative)
This work instead shows how invaluable ground observatories (esp the small ones) are. It's not a super-flashy job; it's a long, time-consuming, and slow-rewarding job. But once you've done it, you get your 15 minutes of fame (actually, in this case, you may make it into the history book).
Re:Wrong priorities... (Score:5, Interesting)
Optimistic, aren't you?
Even worse, if you consider that we are the aliens, and our species has simply invaded and conquered this planet an aen ago. We adapted, survived, and destroyed our own history. If you don't understand the destroyed part of that, go to a library and read some 6,000 year old books. Assuming you knew the language, you wouldn't find the books. They're lost, damaged, and/or intentionally destroyed over the years.
We are the aliens, and our brothern have forgotten about us. We will be stuck here, alone, for a long time.
Re:Why is this considered a galaxy? (Score:4, Funny)
Ah, a parliament or congress.
Re:Dwarf galaxy (Score:5, Informative)
That's right. It's a dwarf galaxy because its actual size is small (compared to other galaxies) but its apparent size is 5,000 times that of the Full Moon because it's so close, as galaxies go.
In case that's not enough to explain it to you, consider that the Moon is much smaller than Jupiter, but appears to be larger because it's much nearer.
Hmm (Score:5, Funny)
Sounds an awful lot like witchcraft, if you ask me. I think we should burn you and the moon, just to be sure.
Re:Star Question (Score:5, Insightful)
Why?
Well, it has to do with the density. Even if there is a galaxy nearby, if the content of a galaxy is sparcely populated by ordinary stars (and they are, I RTFA), you ain't gonna see them. Just like you don't see "humidity" (water molecules) in your room.
Re:Galaxy?! (Score:4, Interesting)
Actually, on an intergalactic scale, this thing is freakishly close. According to TFA this dwarf galaxy is 30,000 light years from Earth. The distance from Earth to the center of the Milky Way galaxy is roughly 27,700 light years (according to Wikipedia [wikipedia.org]). This thing is nearly right on top of us.
BTW, if you're preparing to shoot it, the quote you're looking for is "It's coming right for us!"