Mature, shapely, and with some beautiful bars
Distant galaxy give clues to the structure of the Milky Way.
It’s difficult to know what your home looks like if you don’t, or can’t, leave it.
Take the Milky Way, for instance. Astronomers think it is a barred spiral galaxy, a bit like this one, which is called NGC 7773, which is about 392 million light years away. They can’t be sure, though, mainly because no human-made imaging vessel has thus far escaped the galaxy, turned around and taken a snap.
This image of NGC 7773, taken by NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3), reveals the existence of a series of luminous bars – they appear orangey-brown in this instance.
Astronomers think that the bars develop as galaxies mature, and comprise star-forming material slowly being pulled into the centre of the system.
The Milky Way is a spiral, and quite old, as galaxies go, so it is reasonable to suspect it also contains bars. It might be a very long time indeed, however, before the photographic material exists to prove the contention.