How did we map out the exact shape of the Milky Way, given that we can’t see all of it at once? Or more importantly, how sure are we that we got the shape and size right?
In: Planetary Science
The galaxy is rich with the fundamental gas Hydrogen.
It was discovered that a special condition called hyperfine splitting produces a radio wave emission of particular nature, which can penetrate dust, allowing observations at long galactic distances.
This allows radio astronomers to observe not just the direction and density of emissions, but to also gauge the velocity difference.
From computations on observations, we get a very good understanding of our side of the galaxy, and can model that against millions of other observable galaxies.
That is just one of the more sophisticated measures we have. A fun fact is that a spiral armed galaxy like our own is a common idea of what a galaxy is like, but they are less common in total surveys than one might expect.
https://www.radio2space.com/study-of-the-galactic-hydrogen-distribution-with-spider-300a-radio-telescope/
http://article.sapub.org/10.5923.j.astronomy.20130203.03.html
Latest Answers