October 3, 2012
Spitzer Helping Measure The Universe Precisely
Lee Rannals for redOrbit.com — Your Universe Online
NASA's Spitzer Space Telescope has allowed astronomers to make the most precise measurement yet of the rate at which our universe is expanding.
This expansion rate, also known as the Hubble Constant, is critical for understanding the age and the size of the universe.
In the latest research, Spitzer took advantage of long-wavelength infrared light to make its new measurement.
The newly refined value for the Hubble Constant, according to the latest discovery, is 74.3 plus or minus 1.3 miles per second per megaparsec. A megaparsec is about 3 million light-years.
"Spitzer is yet again doing science beyond what it was designed to do," project scientist Michael Werner at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. "First, Spitzer surprised us with its pioneering ability to study exoplanet atmospheres," said Werner, "and now, in the mission's later years, it has become a valuable cosmology tool."
The findings were combined with published data from NASA's Wilkinson Microwave Anisotropy Probe to get an independent measurement of dark energy. Dark energy is thought to be what is helping pull the universe apart.
Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena said Spitzer is helping scientists to determine the precise rate at which the universe is expanding, as well as measuring the amount of dark energy in the universe from another angle.
Spitzer's infrared vision allows it to see through dust to provide better views of stars called cepheids, which are crucial to the calculations because their distances from Earth can be measured readily.
The telescope observed 10 cepheids in our own Milky Way galaxy, and 80 in a nearby neighboring galaxy called the Large Magellanic Cloud.
The team was able to obtain precise measurements of the stars' brightness, helping to give them an idea of their distances.
"Just over a decade ago, using the words 'precision' and 'cosmology' in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two," Freedman said in a statement. "Now we are talking about accuracies of a few percent. It is quite extraordinary."
The researchers published their findings in the Astrophysical Journal.