Posted on Aug 21, 2020

APOD: 2020 August 21 - Unwinding M51

Maj William W. 'Bill' Price

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Good Red Friday morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Unwinding M51." Also known as the Whirlpool Galaxy, M51 was discovered on October 13, 1773, by Charles Messier while searching for celestial objects that could confuse comet hunters. NGC 5195 (top center) was discovered in 1781 by Pierre Méchain. William Parsons first recognized the logarithmic spiral structure of galaxies like M51 in 1845. But was there any interaction between NGC 5195 and M51? The answer turns out to be yes. It wasn't until the advent of radio astronomy in 1932 and subsequent radio images of M51 that such a relationship could be demonstrated. The designation M51 is now used to refer to the pair of galaxies, in which case the individual galaxies may be referred to as M51a (NGC 5194) and M51b (NGC 5195).

APOD: 2020 August 21 - Unwinding M51

Posted from apod.nasa.gov

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Belated Thank you my friend Maj William W. 'Bill' Price for posting the NASA Astronomy Picture of the Day (APOD) for Friday, August 21, 2020 entitled "Unwinding M51."
Image: Unwinding M51 - Image Credit & Copyright - Data - Hubble Heritage Project, Unwinding - Paul Howell

This mathematically [logarithm] composed image displays a section of the heavens created by God that illustrates some of the beautiful designs in the heavens.

APOD Background
"Explanation: The arms of a grand design spiral galaxy 60,000 light-years across are unwound in this digital transformation of the magnificent 2005 Hubble Space Telescope portrait of M51. In fact, M51 is one of the original spiral nebulae, its winding arms described by a mathematical curve known as a logarithmic spiral, a spiral whose separation grows in a geometric way with increasing distance from the center. Applying logarithms to shift the pixel coordinates in the Hubble image relative to the center of M51 maps the galaxy's spiral arms into diagonal straight lines. The transformed image dramatically shows the arms themselves are traced by star formation, lined with pinkish starforming regions and young blue star clusters. Companion galaxy NGC 5195 (top) seems to alter the track of the arm in front of it though, and itself remains relatively unaffected by this unwinding of M51. Also known as the spira mirabilis, logarthimic spirals can be found in nature on all scales. For example, logarithmic spirals can also describe hurricanes, the tracks of subatomic particles in a bubble chamber and, of course, cauliflower."

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