From a great distance, our galaxy would look like a thin disk of stars that orbit once every few hundred million years around its central region, where hundreds of billions of stars, together with a huge mass of dark matter, provide the gravitational "glue" to hold it all together.
The pull of gravity from the center is much less on the stars and gas clouds at the outer edge of the galaxy, which gives the Milky Way an S-like curved appearance.
Researchers established a robust Galactic disc model based on 1,339 variable stars which are four to 20 times larger than the Sun, and up to 100,000 times more luminous.
Lead researcher Xiaodian Chen, of the Chinese Academy of Sciences in Beijing, said it's hard to determine distances from the sun to the Milky Way's fringes "without having a clear idea of what that disc actually looks like".
Nevertheless, its shape is not unique, as scientists have observed different galaxies in the universe which showed similar spiral patterns to the Milky Way.
"What we've shown is that the young stars in the Milky Way, particularly a type of star called Cepheid variables, actually show this warped distribution". Combined with a Cepheid's observed brightness, its pulsation period can be used to obtain a highly reliable distance.
The Milky Way turned out to be progressively twisted in its outer areas, which is most likely caused by the powerful rotating forces released by the galaxy's massive internal disk, according to the research. "This offers new insights into the formation of our home galaxy", said Macquarie University's Professor Richard de Grijs, senior co-author on the paper.