Closest Spiral Galaxy

NASA's Spitzer Space Telescope has captured a stunning infrared view of the famous spiral galaxy known as Andromeda. Approximately 2.5 million light-years away, Andromeda is the closest spiral galaxy and is the only one visible to the naked eye.

Spitzer's sensitive infrared eyes have detected captivating new features, including bright, aging stars and a spiral arc in the centre of the galaxy. The infrared image also reveals an off-centred ring of star formation and a hole in the galaxy's spiral disk of arms.

Spitzer detects dust heated by stars in the galaxy. Its multiband imaging photometer's 24-micron detector recorded approximately 11,000 separate infrared snapshots over 18 hours to create the new comprehensive mosaic. This instrument's resolution and sensitivity is a vast improvement over previous infrared technologies, enabling scientists to trace the spiral structures within Andromeda to an unprecedented level of detail.

"In contrast to the smooth appearance of Andromeda at optical wavelengths, the Spitzer image reveals a well-defined nuclear bulge and a system of spiral arms," said Dr. Susan Stolovy, a co-investigator from the Spitzer Science Center at the California Institute of Technology, Pasadena.

The galaxy's central bulge glows in the light emitted by warm dust from old, giant stars. Just outside the bulge, a system of inner spiral arms can be seen, and outside this, a well-known prominent ring of star formation.

More pics from the Spitzer Telescope

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology. The Jet Propulsion Laboratory is a division of Caltech.

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October 2006

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