by BDanielMayfield » Sun Aug 11, 2013 2:05 pm
This is a lovely image of M74 to be sure, but it left me wanting to see more. After all, if this galaxy is called “The Perfect Spiral” one would like to see more of its spiral structure. A search for images of M74 led me to this APOD from 4/6/11:
http://apod.nasa.gov/apod/ap110406.html
Another observation in general about the descriptions of spiral galaxies, a very common phrase seems to be that they contain “about 100 billion stars” as is said about this galaxy too. I don’t mean this as a criticism, for even just approximating the stars in a distant galaxy with all the uncertainty involved (size, distance, 3D shape, etc.) would make a more precise accounting quite difficult.
I do wonder though if this could in fact be understating reality as to star counts to a large degree. Our galaxy was said to have “about 100 billion stars” too, although I’ve also read that some more recent estimates peg the Milky Way’s star count at over 1 trillion.
This nice round number of 100 billion comes up a lot in science. Number of stars in a galaxy, number of galaxies in the observable universe, number of neurons in the human brain. It’s a polite, scientific way of saying ‘we don’t really know how many, but it’s a humongous ___ load.’
This is a lovely image of M74 to be sure, but it left me wanting to see more. After all, if this galaxy is called “The Perfect Spiral” one would like to see more of its spiral structure. A search for images of M74 led me to this APOD from 4/6/11: [url]http://apod.nasa.gov/apod/ap110406.html[/url]
Another observation in general about the descriptions of spiral galaxies, a very common phrase seems to be that they contain “about 100 billion stars” as is said about this galaxy too. I don’t mean this as a criticism, for even just approximating the stars in a distant galaxy with all the uncertainty involved (size, distance, 3D shape, etc.) would make a more precise accounting quite difficult.
I do wonder though if this could in fact be understating reality as to star counts to a large degree. Our galaxy was said to have “about 100 billion stars” too, although I’ve also read that some more recent estimates peg the Milky Way’s star count at over 1 trillion.
This nice round number of 100 billion comes up a lot in science. Number of stars in a galaxy, number of galaxies in the observable universe, number of neurons in the human brain. It’s a polite, scientific way of saying ‘we don’t really know how many, but it’s a humongous ___ load.’ :lol2: