13.75
billion years
revised
estimated age
of universe
13.73
billion years
previous
estimated age
of universe
Relic radiation refines age of cosmos
satellite data support inflation, confirm primordial helium
that is believed to accelerate cosmic expan-
sion — “is a wild idea,” admits Bennett.
But with the newest WMAP analysis “we
have confronted the model against the
data in a substantially new way … and this
picture is holding up very well.”
By using WMAP data to measure acous-
tic oscillations — the cosmic equivalent of
sound waves — the team confirmed that
the early universe forged helium as well
as hydrogen, just as the Big Bang theory
has long predicted. Previous studies pro-
vided only indirect evi-
dence of helium. The new
detection “is not a surprise,
but it’s nice to have confir-
mation,” Spergel says.
Researchers also used
the data to discern how
many types of elementary particles called neutrinos exist. Three types
WMAP, launched in 2001, will make its
last observations this fall. The European
Space Agency’s Planck mission, launched
last year, will monitor the microwave
background in even finer detail.
4.5%
Ordinary
matter
Universe composition
By Ron Cowen
By analyzing snapshots of the earliest
light in the universe, cosmologists have
made the most accurate determination
to date of the age of the cosmos, directly
detected primordial helium gas for the
first time and discovered a key signature
of inflation, the leading model of how the
cosmos came to be.
The analysis is based on the first
seven years of data collected by NASA’s
Wilkinson Microwave Anisotropy Probe.
Researchers studying the light, known
as the cosmic microwave background,
unveiled the findings in six papers posted
online at arXiv.org on January 26. The
light was generated in the Big Bang but is
seen as it appeared when it first streamed
freely through space about 400,000 years
later. The light is peppered with hot and
cold spots, signs of tiny primordial lumps
from which galaxies grew.
Using temperature data from the
WMAP satellite and studies of distant
supernovas and other phenomena, scien-
tists including David Spergel of Princeton
University and Charles Bennett of Johns
Hopkins University in Baltimore find that
the universe is 13.75 billion years old, give
or take 0.11 billion. (The team’s previous
calculation, using the same method but
with only five years of observations, had
pegged the universe at 13.73 billion years,
plus or minus 0.12 billion.)
Spirit stuck, but in good spot
after six years on mars and nine months stuck in a sand pit, the driving
days are officially over for the spirit rover, nasa said January 26. the
robotic geologist, roving the red planet since 2004, slid into the pit in
april 2009. “We do not believe that [spirit] is extractable,” said doug
mccuistion, director of the mars exploration program. With the martian
winter approaching, engineers will spend the next few weeks maneuvering spirit into the best position to catch sunlight for power. the rover
will enter hibernation mode in march or april and sleep until august or
september, said project manager John callas of nasa’s Jet propulsion
Lab in pasadena, calif. Lead investigator steve squyres of cornell university said that spirit’s position offers scientific opportunities. “We got
stuck here for a reason, and that reason is this is bizarre soil,” he said.
“We have exciting science planned.” studies of martian atmosphere-soil interactions and of mars’ core top the list. — Lisa Grossman
