Wednesday October 13, 2021’s Smile of the Day: The Whirlpool Galaxy

On this Day:

In 1773, the Whirlpool Galaxy was discovered by astronomer Charles Messier.

(Whirlpool Galaxy image taken by the Hubble Space Telescope. Unrelated objects have been edited out)

The Whirlpool Galaxy, also known as Messier 51a, M51a, and NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus. It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. Its distance is estimated to be 31 million light-years away from Earth.

The galaxy and its companion, NGC 5195, are easily observed by amateur astronomers, and the two galaxies may be seen with binoculars. The Whirlpool Galaxy has been extensively observed by professional astronomers, who study it to understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions.

What later became known as the Whirlpool Galaxy was discovered on October 13, 1773, by Charles Messier while hunting for objects that could confuse comet hunters, and was designated in Messier’s catalogue as M51. Its companion galaxy, NGC 5195, was discovered in 1781 by Pierre Méchain, although it was not known whether it was interacting or merely another galaxy passing at a distance. In 1845, William Parsons, 3rd Earl of Rosse, employing a 72-inch (1.8 m) reflecting telescope at Birr Castle, Ireland, found that the Whirlpool possessed a spiral structure, the first “nebula” to be known to have one. These “spiral nebulae” were not recognized as galaxies until Edwin Hubble was able to observe Cepheid variables in some of these spiral nebulae, which provided evidence that they were so far away that they must be entirely separate galaxies.

The advent of radio astronomy and subsequent radio images of M51 unequivocally demonstrated that the Whirlpool and its companion galaxy are indeed interacting. Sometimes the designation M51 is 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).

Deep in the constellation Canes Venatici, M51 is often found by finding the easternmost star of the Big Dipper, Eta Ursae Majoris, and going 3.5° southwest. Its declination is, rounded, +47°, making it a circumpolar (never setting) for observers above the 43rd parallel north;[a] it reaches a high altitude throughout this hemisphere making it an accessible object from the early hours in November through to the end of May, after which observation is more coincidental in modest latitudes with the risen sun (due to the Sun approaching to and receding from its right ascension, specifically figuring in Gemini, just to the north).

M51 is visible through binoculars under dark sky conditions, and it can be resolved in detail with modern amateur telescopes. When seen through a 100 mm telescope the basic outlines of M51 (limited to 5×6′) and its companion are visible. Under dark skies, and with a moderate eyepiece through a 150 mm telescope, M51’s intrinsic spiral structure can be detected. With larger (>300 mm) instruments under dark sky conditions, the various spiral bands are apparent with HII regions visible, and M51 can be seen to be attached to M51B.

As is usual for galaxies, the true extent of its structure can only be gathered from inspecting photographs; long exposures reveal a large nebula extending beyond the visible circular appearance. In 1984, thanks to the high-speed detector—the so-called image-photon-counting system (IPCS)—developed jointly by the CNRS Laboratoire d’Astronomie Spatiald (L.A.S.-CNRS) and the Observatoire de Haute Provence (O.H.P.) along with the particularly nice seeing offered by the Canada-France-Hawaii-Telescope (C.F.H.T.) 3.60m Cassegrain focus at Mauna Kea summit in Hawaii, Hua et al. detected the double component of the very nucleus of the Whirlpool galaxy (article in Astrophysical Letters and Communications, 1987, vol. 25, pp. 187–204).

In January 2005 the Hubble Heritage Project constructed a 11,477 × 7,965-pixel composite image of M51 using Hubble’s ACS instrument. The image highlights the galaxy’s spiral arms, and shows detail into some of the structures inside the arms.

The Whirlpool Galaxy lies 31 million light-years from Earth and has an estimated diameter of 76,000 light-years. Overall the galaxy is about 43% the size of the Milky Way. Its mass is estimated to be 160 billion solar masses, or around 10.3% of the mass of Milky Way Galaxy.

A black hole, once thought to be surrounded by a ring of dust, but now believed to be partially occluded by dust instead, exists at the heart of the spiral. A pair of ionization cones extend from the active galactic nucleus.

The pronounced spiral structure of the Whirlpool Galaxy is believed to be the result of the close interaction between it and its companion galaxy NGC 5195, which may have passed through the main disk of M51 about 500 to 600 million years ago. In this proposed scenario, NGC 5195 came from behind M51 through the disk towards the observer and made another disk crossing as recently as 50 to 100 million years ago until it is where we observe it to be now, slightly behind M51.

The central region of M51 appears to be undergoing a period of enhanced star formation. The present efficiency of star formation, defined as the ratio of mass of new stars to the mass of star-forming gas, is only ~1%, quite comparable to the global value for the Milky Way and other galaxies. It is estimated that the current high rate of star formation can last no more than another 100 million years or so.

Three supernovae have been observed in the Whirlpool Galaxy. (Per Wikipedia).

A supernova is the biggest explosion that humans have ever seen. Each blast is the extremely bright, super-powerful explosion of a star (per

First, a Story:

Who’s the best basketball player who comes from a galaxy far far away?  Obi wan Kobe

Second, a Song:

Monty Python (also collectively known as the Pythons) were a British surreal comedy troupe who created the sketch comedy television show Monty Python’s Flying Circus, which first aired on the BBC in 1969. Forty-five episodes were made over four series. The Python phenomenon developed from the television series into something larger in scope and influence, including touring stage shows, films, albums, books and musicals. The Pythons’ influence on comedy has been compared to the Beatles’ influence on music. Regarded as an enduring icon of 1970s pop culture, their sketch show has been referred to as being “an important moment in the evolution of television comedy”.

Broadcast by the BBC between 1969 and 1974, Monty Python’s Flying Circus was conceived, written and performed by its members Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones, and Michael Palin. Loosely structured as a sketch show, but with an innovative stream-of-consciousness approach aided by Gilliam’s animation, it pushed the boundaries of what was acceptable in style and content. A self-contained comedy team responsible for both writing and performing their work, the Pythons had creative control which allowed them to experiment with form and content, discarding rules of television comedy. Following their television work, they began making films, including Monty Python and the Holy Grail (1975), Life of Brian (1979) and The Meaning of Life (1983). Their influence on British comedy has been apparent for years, while in North America, it has coloured the work of cult performers from the early editions of Saturday Night Live through to more recent absurdist trends in television comedy. “Pythonesque” has entered the English lexicon as a result.

At the 41st British Academy Film Awards in 1988, Monty Python received the BAFTA Award for Outstanding British Contribution To Cinema. In 1998, they were awarded the AFI Star Award by the American Film Institute. Many sketches from their TV show and films are well-known and widely quoted. Both Holy Grail and Life of Brian are frequently ranked in lists of greatest comedy films. In a 2005 poll of over 300 comics, comedy writers, producers and directors throughout the English-speaking world to find “The Comedian’s Comedian”, three of the six Pythons members were voted to be among the top 50 greatest comedians ever: Cleese at No. 2, Idle at No. 21, and Palin at No. 30.

“Galaxy Song” is a Monty Python song written by Eric Idle and John Du Prez.

The song first appeared in the 1983 film Monty Python’s The Meaning of Life and was later released on the album Monty Python Sings. The song was released as a single in the UK on 27 June 1983 when it reached No. 77 in the charts and again on 2 December 1991 as a follow-up to the successful reissue of Always Look on the Bright Side of Life. In 2014 the song was featured in the live stage show Monty Python Live (Mostly) which was followed by another single release on 13 April 2015, this time in collaboration with Stephen Hawking (per Wikipedia).

This is a cover and adaptation of the Monty Python song “Galaxy Song” from 1983, with some updates and a rewritten final verse based on our improved knowledge of the universe by StefanPWinc. states: “I create fun and interesting videos about Science, aimed at a wide audience from young kids to adults. These include science songs like “The Solar System Song”, and other explanatory videos, inspired by those like Bill Nye and Neil deGrasse Tyson. I make my own animations and music to go along with my videos, because the wonder of visualizing these amazing things, in books and in documentaries, was part of what got me excited about science as a kid.” I hope you enjoy this!


And if you wish to view the original version featuring the Monty Python gang with Stephen Hawking, you can view it here: 


Thought for the Day:

“The spiral in a snail’s shell is the same mathematically as the spiral in the Milky Way galaxy, and it’s also the same mathematically as the spirals in our DNA. It’s the same ratio that you’ll find in very basic music that transcends cultures all over the world.” – Joseph Gordon-Levitt

Have a great day!

Dave & Colleen

© 2021 David J. Bilinsky and Colleen E. Bilinsky

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