Take a Flight Through Our Universe, Thanks to New 3-D Map of the Sky

The Sloan Digital Sky Survey III (SDSS-III) has released the largest three-dimensional map of massive galaxies and distant black holes ever created, and it pinpoints the locations and distances of over a million galaxies. It covers a total volume equivalent to that of a cube four billion light-years on a side.

A video released with the map takes viewers on an animated flight through the Universe as seen by SDSS. There are close to 400,000 galaxies in the animation, which places zoomed-in images of nearby galaxies at the positions of more distant galaxies mapped by SDSS.

“We want to map the largest volume of the universe yet, and to use that map to understand how the expansion of the universe is accelerating,” said Daniel Eisenstein (Harvard-Smithsonian Center for Astrophysics), the director of SDSS-III.

The map is the centerpiece of Data Release 9 (DR9), which publicly releases the data from the first two years of a six-year survey project. The release includes images of 200 million galaxies and spectra of 1.35 million galaxies. (Spectra take more time to collect than photographs, but provide the crucial third dimension by letting astronomers measure galaxy distances.)

“Our goal is to create a catalog that will be used long after we are done,” said Michael Blanton of New York University, who led the team that prepared Data Release 9.

The release includes new data from the ongoing SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), which will measure the positions of massive galaxies up to six billion light-years away, as well as quasars – giant black holes actively feeding on stars and gas – up to 12 billion light-years from Earth.

BOSS is targeting these big, bright galaxies because they live in the same places as other galaxies and they’re easy to spot. Mapping these big galaxies thus provides an effective way to make a map of the rest of the galaxies in the universe.

With such a map, scientists can retrace the history of the universe over the last six billion years. With that history, they can get better estimates for how much of the universe is made up of “dark matter” – matter that we can’t directly see because it doesn’t emit or absorb light – and “dark energy,” the even more mysterious force that drives the accelerating expansion of the universe.

“Dark matter and dark energy are two of the greatest mysteries of our time,” said David Schlegel of Lawrence Berkeley National Laboratory, the principal investigator of BOSS. “We hope that our new map of the universe can help someone solve the mystery.”

This release is being issued jointly with the SDSS-III Collaboration.

All the data are available now on the Data Release 9 website at http://www.sdss3.org/dr9. The new data are being made available to astronomers, as well as students, teachers, and the public. The SkyServer website includes lesson plans for teachers that use DR9 data to teach astronomy and other topics in science, technology, and math. DR9 data will also feature in a new release of the Galaxy Zoo citizen science project, which allows online volunteers to contribute to cutting-edge astronomy research.

Image caption: This is a still image from the fly-through video of the SDSS-III galaxies mapped in Data Release 9. Credit: Miguel A. Aragón (Johns Hopkins University), Mark SubbaRao (Adler Planetarium), Alex Szalay (Johns Hopkins University), Yushu Yao (Lawrence Berkeley National Laboratory, NERSC), and the SDSS-III Collaboration

Source: CfA

12 Replies to “Take a Flight Through Our Universe, Thanks to New 3-D Map of the Sky”

  1. With each spot of light in this video representing a galaxy as large (on average) as our own, it only takes a few seconds to realize just how immense space really is.

  2. The SDSS looks out to where the red shift factor is z = .15. This means the galaxies are moving out at v = zc = 4.5×10^4km/s. If we use the Hubble relationship v = Hd, for H = 74km/sec/Mpc (7.4×10^{-5}km/s/pc or 2.27×10^{-5}km/s/ly) we can compute the distance out with d = v/H,

    d = (4.5×10^4km/s)/(2.27×10^{-5}km/s/ly) = 1.98×10^9ly.

    This is a fraction of the distance out to the cosmological horizon ~ 1.2×10^{10}ly. The CMB is around 4.5×10^{10}ly and the particle horizon is about 5×10^{11}ly. The cosmological horizon is the limit beyond which we can’t send a message to a galaxy beyond it. The particle horizon is the limit beyond which we can observe the universe.

    Consequently this video displays about 4.5×10^{-3} of the universe we may be able to send a signal to, or for science fiction aficionados this is the fraction of the universe of some possible cosmic empire. Of course in the exponential accelerated expanding universe over time more of this will slip past the cosmological horizon and red shift to asymptotic invisibility. This is 8.5×10^{-5} of the universe out to the CMB and 6.2×10^{-8} fraction of the universe that we can possibly observe or receive signal data from. So this is a pretty small portion of the whole thing.

    Of course this region out to the cosmological horizon is a distance reflecting a vacuum bubble nucleation in a flat space with inflationary pressure. Our “bubble,” or sometimes called a pocket universe, is just one of a vast number (possibly infinite) of such pockets. The space, a Euclidean R^3 space that expands in a four dimensions R^1xR^3, is a configuration of strings on a D3-brane. This particular D3-brane is one of a vast number (infinite?) of D3-branes in a foliation within the superspace of 11 dimensions.

    So this image is a very local slice of the whole thing, though of course it is impressive. We just recently landed a rover on Mars, which is an even more local accomplishment.


  3. What a great video. How many galaxies are there in our universe ? Could we find a way to know something like that. I really do not know

    1. I think I read the current estimate is about 100 billion galaxies. Each with about 100 billion stars. Then what if there’s more than one universe?? 🙂

      1. That is the visible universe. We don’t know what portion of the universe we live in (never mind others) the light cone limited visible universe comprises.

  4. It would be interesting to start out zoomed in on our own galaxy, with a caption that says “You are here”, so we can see where we are with respect to all the other galaxies.

  5. Who said it’s impossible for mankind to travel faster than the speed of light? The Sloan Digital Time Machine proves that it IS possible! At least, in the mind’s eye…. Nice!

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