Spitzer space telescope observations reveal expansion rate of the Universe

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How the Hubble constant is measured (Image: NASA)

Cutaway drawing of the Spitzer space telescope (Image: NASA)

External drawing of the Spitzer space telescope (Image: NASA)

Composite image of the Spitzer space telescope in its Earth-following orbit around the Sun (Image: NASA)

The Spitzer space telescope shortly prior to launch (Photo: NASA)

Observations of Cepheid variable stars by the Spitzer space telescope established the precision relation between brightness and oscillation period (Image: NASA)

Parallax beautifully illustrated by the reflection in the water appearing to show the Sun at the top of the streetlamp although, along the direct path, it is well above the streetlamp – parallax is the apparent movement of the streetlamp relative to the distant Sun (Photo: Brocken Inaglory via Wikimedia Commons)

The Large Magellanic Cloud photographed in false color infrared light by the Spitzer space telescope and the Herschel space observatory (Photo: NASA)

Spitzer astrophoto of Delta Cephei showing mass loss, formation of a bow wave, and other effects that can change the apparent brightness of the Cepheid variable star (Photo: NASA)

Cepheid variable RS Puppis is surrounded by a nebula of dust and gas – most clearly at the lower left, the light echoes of the star's variable luminosity can be seen encircling the star, whose light is blocked by a linear obstruction (Photo: ESA)

The parallax measurement of the distance of a star

Redshifts measured for a series of galaxies located at increasing distances (Photo: NASA)

A Hubble photo of galaxy NGC 4603, at 33 Mpc (108 Mly) the most distant galaxy for which individual Cepheids have been studied (Photo: NASA)

The Spitzer space telescope has peered through dust and gas to establish a new value for the Hubble Constant (Image: NASA)

Article Summary

The size and age of our Universe is not only a critically important issue in cosmology, but is also among the most controversial and delicate of the cosmological questions. Infrared observations made using NASA's Spitzer Space Telescope have now given us the most precise estimate yet of the rate at which our Universe is expanding. The key was not the discovery of a new method for measuring distance. Rather, astronomers discovered how to measure brightness more accurately. The new value for the Hubble constant, good to within three percent, is 74.3 kilometers per second per megaparsec (km/s/Mpc).

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