NASA’s Infrared Observatory Measures Expansion of Universe

NASA’s Infrared Observatory Measures Expansion of Universe
" H0 is around 74 +/-  0.4 (statistical)  km/(s Mpc ) "

Spitzer Telescope

Astronomer Edwin, P. Hubble in 1920’s confirmed our Universe has been expanding.  Astronomers invested lot of effort to understand this expansion rate whether its speeding up or speeding down or remaining constant. In late 1990’s they found the expansion is speeding up. Saul Perlmutter, Brian Schmidt, and Adam Riess in 2011 were awarded Nobel Prize in Physics for their work on demonstrating positive acceleration of the expansion rate using Supernova data.

The next immediate question is to find the expansion rate. The parameter H0 known as Hubble constant gives us the expansion rate of the Universe. For most of the half of 20th century the value of H0 was believed to be around 50 – 90 km/(s Mpc ).  Data from Hubble Space Telescope, WMAP, Chandra X-ray Observatory, etc led us to conclude that the value of H0 to be around 70 – 77 km/(s Mpc ) a much more precise value reducing the uncertainty.

The slope of the graph gives the Hubble constant

To measure expansion rate of universe it is absolutely necessary to look for distant objects. Infrared observations help us to look into such distant objects since scattering of light is low at infrared wavelengths. The Spitzer telescope one of the NASA’s Great Observatories Program works at Infrared region of the spectrum. The Spitzer telescope gave a better view of variable stars called Cepheids and gave precise measurements on their brightness to improve the value of Hubble constant.

Finally analyzing the data obtained from Spitzer telescope scientists have now concluded the value of H0 to be around
74 +/-  0.4 (statistical)  km/(s Mpc )
74.3 +/- 2.1 (systematic)   km/(s Mpc )
a much better reduction in the uncertainty value.

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ISS Team

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