With billions of stars apiece, most galaxies appear only as indistinct shapes through even powerful telescopes.
Image credit: NASA, ESA and T.M. Brown (STScI), of background galaxies seen through the disk of... [+]
But thanks to:
- being above the atmosphere,
- looking at the closest galaxies,
- and imaging away from the crowded center,
the Hubble Space Telescope actually can resolve individual, extragalactic stars.
Image credit: NASA, ESA and T.M. Brown (STScI), of a small, star-rich region in the Andromeda... [+]
What it reveals is that galaxies are not opaque and dense, but rather a glittering set of jewels separated by great interstellar distances.
From 2004-2007, Hubble took four high resolution images of Andromeda, our closest large neighbor galaxy.
While they look similar on the surface, they show vastly different parts of this galaxy.
Image credit: NASA, ESA and T.M. Brown (STScI), of the stars in Andromeda's outer disc. Via... [+]
The outer disc of Andromeda (above) shows a wide variety of stars, including many Sun-like ones and older variables.
Image credit: NASA, ESA and T.M. Brown (STScI), of the stars in Andromeda's giant stellar stream.... [+]
The stars from the giant stellar stream are also densely packed, obscuring the Universe beyond.
Image credit: NASA, ESA and T.M. Brown (STScI), of the sparser, older stars in Andromeda's halo,... [+]
But the images of the diffuse halo are low in density, revealing many background galaxies.
Image credit: NASA, ESA and T.M. Brown (STScI), of another view of the sparser, older stars in... [+]
These low-density regions contain many of the oldest, least evolved stars, lower in heavy elements than those found in the disk.
Image credit: NASA, ESA and T.M. Brown (STScI), of stars in the Andromeda galaxy's halo, with a few... [+]
Meanwhile, the galaxies visible through the gaps in the stars are hundreds of millions to billions of light years distant.
Image credi:t NASA, ESA and T.M. Brown (STScI), of background galaxies seen through the halo of... [+]
Mostly Mute Monday tells the story of a single astronomical phenomenon or object in visuals, images and video in no more than 200 words.
