Spiral Galaxy NGC 7640 in Andromeda | Hubble Space Telescope

Spiral Galaxy NGC 7640 in Andromeda | Hubble Space Telescope

Not to be confused with our neighboring Andromeda Galaxy, the Andromeda constellation is one of the 88 modern constellations. More importantly for this image, it is home to the pictured NGC 7640.

Distance from Earth: 30 million light years

Many classifications are used to identify galaxies by shape and structure—NGC 7640 is a barred spiral type. These are recognizable by their spiral arms that fan out not from a circular core, but from an elongated bar cutting through the galaxy’s center. Our home galaxy, the Milky Way, is also a barred spiral galaxy. NGC 7640 might not look much like a spiral in this image, but this is due to the orientation of the galaxy with respect to Earth—or to Hubble. We often do not see galaxies face on. This can make features, such as spiral arms, less obvious.

There is evidence that NGC 7640 has experienced galactic interactions in its past. Galaxies contain vast amounts of mass, and therefore affect one another via gravity. Sometimes these interactions can be mild, and sometimes hugely dramatic, with two or more colliding and merging into a new, larger galaxy. Understanding the history of a galaxy, and what interactions it has experienced, helps astronomers to improve their understanding of how galaxies—and the stars within them—form.

NGC 7640 was discovered on October 17, 1786 by the English astronomer William Herschel. 

Credit: ESA/Hubble & NASA
Release Date: Feb. 6, 2017

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