Video transcript
The video is 6 minutes and 56 seconds long.
Produced by the American Museum of Natural History, February 2006.
Visual: Image of mountains
Speaker: Michael Strauss, Princeton University
People have a natural fascination with the night sky.
Visual: Michael Strauss on camera
They have a natural fascination to try to understand the world in which we live, the world in the grandest sense, not just the Earth.
Visual: Earth rotating and moving through space
And astronomy teaches us something about how the Earth fits into the much larger scheme.
Title: Sloan Digital Sky Survey
Visual: Montage showing telescope being unveiled
The Sloan Digital Sky Survey is the largest and most ambitious survey of the sky to date.
Visual: Montage of telescope opening
The survey uses a two-and-a-half meter telescope at Apache Point, New Mexico. And it has two principal instruments. One is an imaging camera that can take image of a large chunk of sky at once; and a spectrograph which can measure the spectrum of an object that allows us to determine their distances, so this gives us a three-dimensional map of the Universe.
Visual: John Barentine on camera
Speaker: John Barentine, Apache Point Observatory
The idea behind the Sloan Digital Sky Survey is that it is a survey. So rather than focusing in on a single object at a time like most people think of when they imagine astronomers at telescopes,
Visual: Montage of images from the Sloan Digital Sky Survey
Image caption: Star field in the constellation Cygnus
Image caption: Galaxy NGC 1068
in this case we're taking in a very large field of view and building up a picture of the Universe as a whole rather than just studying our particular corner of it.
Visual: Montage of control room and telescope being prepped
Right now we're sort of putting everything together for the night in terms of checking all the telescope subsystems to make sure they're working properly, looking at calibration data to make sure that looks correct for the night. And then as soon as that's all finished we'll be headed down to the telescope to open it up.
Visual: Michael S. Turner on camera
Speaker: Michael S. Turner, National Science Foundation
The Sloan Digital Sky Survey has two goals. One is to digitize the part of the sky that we can see from the Northern Hemisphere, about 10,000 square degrees, and the other is to find the distances to about a million galaxies to define the large-scale structure that exists in the Universe.
Visual: Telescope being opened and prepped
Speaker: Telescope Operator
O.K., 78 percent is what I'm seeing on the humidity so we are still O.K. to go. The focus is coming along, we are just about there.
Visual: Montage of control room
Speaker: Michael S. Turner, National Science Foundation
So you find the brightest galaxies in that part of the sky that are going to be your sample of a million.
Visual: Operators in control room
Speaker: Telescope Operator
It looks very good. Nice and round, nice and tight.
Visual: Montage of control room
Speaker: Michael S. Turner, National Science Foundation
You accurately measure the positions.
Visual: Montage of drilling at the University of Washington
You send those positions to the University of Washington, where they accurately drill holes in the plate to let the light through from that galaxy.
Visual: Plug plate from the Sloan Digital Sky Survey
Visual: John Barentine holding a plug plate
Speaker: John Barentine, Apache Point Observatory
This is essentially a small piece of the overall map that we're making of the Universe.
Visual: John Barentine's hand moving across plug plate
This corresponds to an area on the sky about three and a half degrees wide, or roughly six times the diameter of the full moon.
Visual: John Barentine holding a plug plate
At each one of these locations where you see a hole with light shining through it, there is an object: a galaxy, a quasar, or an interesting star in our own galaxy.
Visual: Montage of plug plates being plugged with optical fibers
And for each one of these holes, we will insert an optical fiber. The optical fiber guides the light from that, and only that, object down into our spectrograph, which records an optical spectrum of the object.
Visual: Montage of computer screens
Speaker: Michael S. Turner, National Science Foundation
So you take the light and break it up into the colors not just a rainbow, but make precise measurements of each narrow band of color, and when you do that, it tells you the story of the galaxy.
Visual: Montage of Images from the Sloan Digital Sky Survey
Image caption: Galaxy NGC 7814
Image caption: Galaxy M101
Image caption: Galaxy M51
Image caption: Dark clouds in the constellation Serpens
Speaker: John Barentine, Apache Point Observatory
The spectra that we take with these plates tells us a lot of information about the galaxies. Most important are their distances. We want that information in order to construct a sort of three-dimensional map of the Universe.
Visual: 3-D animation
Caption: Data from the Sloan Galaxy Catalogue
Caption: Part of the Sloan survey area
And really for the first time we're beginning to see the large-scale structure of the Universe in three dimensions instead of just a flat plane. And that tells us something about what the conditions must have been like in the early Universe to result in that three- dimensional structure.
Visual: Montage of plug plates being wheeled out to the telescope
Speaker: Michael Strauss, Princeton University
The desire has always been there. Astronomers have always wanted to survey the sky and get a complete census, and indeed the old-fashioned way of doing this was with photographic plates.
Visual: Michael Strauss on camera
And that had its limitations, the most principal one of which was that photographic film is quite a bit less sensitive than are these modern electronic detectors,
Visual: Plug plate being wheeled out to telescope
which are the same technology that you'll find in a digital camera, and so that's the enabling technology.
Visual: Telescope at dusk
Visual: Montage of control room
Speaker: John Barentine, Apache Point Observatory
On any given night as you watch the imaging information come in from the telescope, you see all manner of objects—galaxies, quasars, and interesting stars displayed on our computer monitors. And it's almost like seeing animals in a zoo in the sense that no two of them are alike, and they each have their own history.
Visual: John Barentine on camera
So not only have we been able to make comments on the way objects evolve and interact with each other,
Visual: Montage of control room
but then as an assembly how they relate some information about the Universe as a whole.
Visual: Montage of Sloan Images
Image caption: The Cepheus A (East) cloud
Image caption: Galaxy NGC 660
Speaker: Michael S. Turner, National Science Foundation
I think what has made the Sloan interesting was that previous surveys, of 50,000 objects, it wasn't clear we had a fair sample of the Universe.
Visual: Michael S. Turner on camera
It wasn't clear that we had seen all that there was to see. And the Sloan has now proven to be big enough that we know we have a fair sample of the Universe. And we were able to more accurately measure its features.
Visual: Montage of Sloan images
Image caption: Virgo cluster of galaxies
Image caption: Star birth field in the constellation Taurus
Image caption: Galaxy NGC 1055
Image caption: Galaxy UGC 3974
Image caption: Galaxy NGC 6340
Image caption: Galaxy NGC 4395
Image caption: Reflection Nebula in the constellation Andromeda
Speaker: Michael Strauss, Princeton University
The Sloan has enabled us to see the Universe in fine detail, uncovering everything from the closest and dimmest stars in our own Milky Way to the furthest quasars in the most remote reaches of the cosmos. On one side, we realize how small we are to be this tiny little speck in this enormously vast Universe in which distances are measured in billions of light-years, a scale that is just unimaginable on a human scale.
Visual: Michael Strauss on camera
On the other hand, it's enormously uplifting to realize that we as humans can understand all that.
Visual: Montage of Sloan images
Image caption: Galaxy UGC 5364
Image caption: Star forming region M78 in Orion
We can comprehend it, and by carrying out observations learn new things. To really understand the Universe in which we live.