Our understanding of galaxies and the cosmic frontier is increasing
at phenomenal speed. This section is an attempt to keep up with
the most important advances. Several websites are especially focused
on the latest news in space science. Of these, I recommend ...
WMAP Heralds Era of Precision Cosmology
The Wilkinson Microwave Anisotropy Probe (WMAP) has finished
its first year of imaging the faint microwave radio emission
that pervades the entire sky. This emission is identified as
coming from the Universe when it had cooled to a temperature
of 3,000 degrees Kelvin, 380,000 years after the Hot Big Bang.
The emission originally arose as visible light akin to that
of the solar surface, but has since been redshifted by universal
expansion to the microwave part of the electromagnetic spectrum.
WMAP's first-year map reveals miniscule irregularities that
confirm some of the most important findings in cosmology --
the study of the Universe as a whole. From the mottled emission,
WMAP scientists have determined that
* Our Universe is exquisitely "flat" in topology,
such that two initially parallel light rays will stay parallel
forever. A flat Universe is one of the key predictions of cosmic
inflation, a theory that pertains to the very earliest moments
of the Universe.
* The Universe and all it contains originated in a Hot Big
Bang 13.7 billion years ago.
* The Universe is expanding like a stretchy sheet at a rate
of 71 kilometers per second per megaparsec of distance, where
one megaparsec equals 3.26 million light-years.
* The matter-energy in the Universe is made up of 4% ordinary
matter -- most of which is dark, 23% dark matter of unknown
constitution, and 73% dark energy of even more unknown nature.
* The first stars in the Universe were formed less than 200
million years after the Big Bang, less than 1.5% of the total
time that has transpired since then.
These far-reaching conclusions are based on the most precise
measurements of the cosmic microwave background ever attained.
They await confirmation from the additional WMAP data that are
accruing, from the European Planck mission that has yet to launch,
and from other scientists who may hold different interpretations
of the same data.