NGC 7331, Caldwell 30, The Milky Way's Twin, Spiral Galaxy
NGC 7331 and sometimes referred to as our galaxy's twin, is found in the constellation Pegasus at a distance of 50 million light-years. The image was obtained by Spitzer's infrared array camera is a four-color composite of invisible light, showing emissions from wavelengths of microns (blue), microns (green), microns (yellow) and microns (red). One feature that stands out in the Spitzer image is the ring of actively forming stars that surrounds the galaxy center (yellow). This ring, with a radius of nearly 20,000 light-years, is invisible at shorter wavelengths, yet has been detected at sub-millimeter and radio wavelengths. Spitzer measurements suggest that the ring contains enough gas to produce four billion stars like the Sun. Three other galaxies are seen below NGC 7331, all about 10 times farther away. From left to right are NGC 7336, NGC 7335 and NGC 7337. The blue dots scattered throughout the images are foreground stars in the Milky Way; the red ones are galaxies that are even more distant.
Size: 4050px × 2631px
Photo credit: © Photo Researchers / Alamy / Afripics
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