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PASADENA, Calif. -- Scientists say that the Planck space mission has released the most
accurate and detailed map ever made of the oldest light in the universe,
revealing new information about its age, contents and origins.
The full-sky map from the Planck mission above shows matter between Earth and
the edge of the observable universe. Regions with less mass show up as
lighter areas while regions with more mass are darker. The grayed-out
areas are where light from our own galaxy was too bright, blocking
Planck's ability to map the more distant matter.
Normal matter, which is made up of atoms, is only a small percent of the total mass in our universe. Most of the matter in the universe is dark -- that is, it does not emit or absorb any light -- so creating a map of its distribution is challenging. To make the full-sky map, the Planck team took advantage of the fact that all matter, even dark matter, has gravity that will affect light traveling to us from near the very edge of the observable universe. Planck mapped this light, called the cosmic microwave background, with exquisite precision over the whole sky, enabling scientists to create this matter map.
The map results suggest the universe is expanding more slowly than
scientists thought, and is 13.8 billion years old, 100 million years
older than previous estimates. The data also show there is less dark
energy and more matter, both normal and dark matter, in the universe
than previously known. Dark matter is an invisible substance that can
only be seen through the effects of its gravity, while dark energy is
pushing our universe apart. The nature of both remains mysterious.
"Astronomers worldwide have been on the edge of their seats waiting for
this map," said Joan Centrella, Planck program scientist at NASA
Headquarters in Washington. "These measurements are profoundly important
to many areas of science, as well as future space missions. We are so
pleased to have worked with the European Space Agency on such a historic
endeavor."
The map, based on the mission's first 15.5 months of all-sky
observations, reveals tiny temperature fluctuations in the cosmic
microwave background, ancient light that has traveled for billions of
years from the very early universe to reach us. The patterns of light
represent the seeds of galaxies and clusters of galaxies we see around
us today.
"As that ancient light travels to us, matter acts like an obstacle
course getting in its way and changing the patterns slightly," said
Charles Lawrence, the U.S. project scientist for Planck at NASA's Jet
Propulsion Laboratory in Pasadena, Calif. "The Planck map reveals not
only the very young universe, but also matter, including dark matter,
everywhere in the universe."
The age, contents and other fundamental traits of our universe are
described in a simple model developed by scientists, called the standard
model of cosmology. These new data have allowed scientists to test and
improve the accuracy of this model with the greatest precision yet. At
the same time, some curious features are observed that don't quite fit
with the simple picture. For example, the model assumes the sky is the
same everywhere, but the light patterns are asymmetrical on two halves
of the sky, and there is a spot extending over a patch of sky that is
larger than expected.
"On one hand, we have a simple model that fits our observations
extremely well, but on the other hand, we see some strange features
which force us to rethink some of our basic assumptions," said Jan
Tauber, the European Space Agency's Planck project scientist based in
the Netherlands. "This is the beginning of a new journey, and we expect
our continued analysis of Planck data will help shed light on this
conundrum."
The findings also test theories describing inflation, a dramatic
expansion of the universe that occurred immediately after its birth. In
far less time than it takes to blink an eye, the universe blew up by 100
trillion trillion times in size. The new map, by showing that matter
seems to be distributed randomly, suggests that random processes were at
play in the very early universe on minute "quantum" scales. This allows
scientists to rule out many complex inflation theories in favor of
simple ones.
The newly estimated expansion rate of the universe, known as Hubble's
constant, is 67.15 plus or minus 1.2 kilometers/second/megaparsec. A
megaparsec is roughly 3 million light-years. This is less than prior
estimates derived from space telescopes, such as NASA's Spitzer and
Hubble, using a different technique. The new estimate of dark matter
content in the universe is 26.8 percent, up from 24 percent, while dark
energy falls to 68.3 percent, down from 71.4 percent. Normal matter now
is 4.9 percent, up from 4.6 percent
Planck is a European Space Agency mission. NASA contributed
mission-enabling technology for both of Planck's science instruments,
and U.S., European and Canadian scientists work together to analyze the
Planck data.
SOURCE: NASA
Image Credit: ESA/NASA/JPL-Caltech
Video Credit: NASA/JPL
