Mapping the Universe - Mapping Scientific Frontiers: The Quest for Knowledge Visualization - page 68

Fig. 2.20 The CfA Great Wall - the structure is 500 million light-years across. The
Harvard-Smithsonian Center for Astrophysics redshift survey of galaxies in the northern celestial
hemisphere of the universe has revealed filaments, bubbles, and, arching across the middle of the
sample
the even bigger Sloan Great Wall discovered a few years later in 2003. The CfA
Great Wall is like a giant quilt of galaxies across the sky (Geller and Huchra 1989 ).
A random distribution cannot readily explain such a coherent structure. Even larger
mapping and surveying projects were undertaken. Stephen Landy ( 1999 ) explained
the Las Campanas Redshift Survey, which took place between 1988 and 1994. It
would take a lengthy explore time to photograph the most distant galaxies because
they were faint. The Las Campanas survey chose to slice through the universe and
concentrated on a very deep and wide but think slice (See Fig. 2.21 ).
Astronomers have begun to catalogue 100 million of the brightest galaxies
and 100,000 quasars, which are the exploding hearts of galaxies, using a device
called two-degree field spectrograph (2dF). The 2dF Galaxy Redshift survey is an
international collaboration involving more than 30 scientists from 11 institutions. It
is due to complete in 2006. The survey aims to learn more about the structure of the
Universe, how galaxies are made and how they form into larger structures.
The 2dF instrument is one of the most complex pieces of astronomical “camera”
ever built. It uses 400 optical fibers, all of which can be positioned by an incredibly
accurate robotic arm in about one hour. The 2dF instrument allows astronomers to
observe and analyze 400 objects at once, and on a long clear night, they can log
the positions of more than 2,000 galaxies. It has taken less than 2 years to measure
the distances for 100,000 galaxies. Without the 2dF instrument, this project would
have taken decades. Figure 2.22 shows a virtual scene of flying through a three-
dimensional model of the universe.