Full Answer
As with many contemporary mysteries in astronomy, the answer is dark matter. The Milky Way is thought to be home to a halo of dark matter – matter that cannot be detected except through its gravitational influence – which makes up approximately 80-90% of its mass.
The total mass of the Galaxy is about 2 × 1012MSun. As much as 95% of this mass consists of dark matter that emits no electromagnetic radiation and can be detected only because of the gravitational force it exerts on visible stars and interstellar matter.
1) Approximately 90 percent of the mass of the Milky Way is located in the halo of the galaxy in the form of dark matter.
Most of the rest of the mass is locked up in dark matter, an invisible and mysterious substance that acts like scaffolding throughout the universe and keeps the stars in their galaxies.
Combined with other kinematic information about these stars, the scientists calculate that the mass of the galaxy is between 1.2 and 1.9 trillion solar masses, adding significant precision to the previous estimates. "Constraining Milky Way Mass with Hypervelocity Stars," G.
Why do we believe that most of the mass of the Milky Way is in the form of dark matter? The orbital speeds of stars far from the galactic center are surprisingly high, suggesting that these stars are feeling gravitational effects from unseen matter in the halo.
Most of the mass of our galaxy lies between Earth and the Galactic center. Between us and the Galactic Center lie about 100 billion solar masses.
Astronomers can calculate the masses of some spiral galaxies by determining their rotation speed by measuring the Doppler shift of various spectral lines versus distance from the galactic center. The mass within any given radius then follows directly from Newton's laws.
The two main candidates for making up the majority of dark matter are WIMPs (weakly interacting massive particles) and dim but ordinary objects such as planets or brown dwarfs. Scientists can estimate the amount of matter in the latter form by searching for gravitational lensing events caused by such objects.
The Milky Way galaxy is made of billions of stars, and gas and dust, all bound together by mutual gravitational attraction, as well as a lot of dark matter. The diameter of our galaxy is about 100,000 light years [e1] across (the visible material at least – the dark matter halo goes beyond that).
C) 100,000 light years. C) 100,000 light years. About how much mass does our galaxy contain? B) 1 billion solar masses.
NEW YORK — All the stars planets and galaxies that can be seen today make up just 4 percent of the universe. The other 96 percent is made of stuff astronomers can't see detect or even comprehend.
There are over 100 billion stars in our galaxy.
The nucleus of the galaxy has many stars "crowded" together.
The galactic halo is filled with metal-poor stars.
Open clusters lie along the Milky Way and half of the globular clusters are in or near the constellation Sagittarius.
Objects with large proper motion tend to be closer than objects with small proper motion.
The Galaxy's rotation curve flattens out at great distances.
Radio telescopes can see through interstellar gas and dust.