November 20, 2016
You share your birthday with the light of distant galaxies that has been traveling for millions of years just to arrive here, now, alongside...
NGC 4414: A Flocculent Spiral Galaxy
Birthday · November 20, 2016
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APOD published November 20, 2016. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
How much mass do flocculent spirals hide? The featured true color image of flocculent spiral galaxy NGC 4414 was taken with the Hubble Space Telescope to help answer this question. The featured image was augmented with data from the Sloan Digital Sky Survey (SDSS). Flocculent spirals -- galaxies without well-defined spiral arms -- are a quite common form of galaxy, and NGC 4414 is one of the closest. Stars and gas near the visible edge of spiral galaxies orbit the center so fast that the gravity from a large amount of unseen dark matter must be present to hold them together. Understanding the matter and dark matter distribution of NGC 4414 helps humanity calibrate the rest of the galaxy and, by deduction, flocculent spirals in general. Further, calibrating the distance to NGC 4414 helps humanity calibrate the cosmological distance scale of the entire visible universe. Free Download: APOD 2017 Calendar: NASA Images