The hypothesis isn't dark matter perfect, but the alternatives are

 Dark matter 

The Magellanic Cloud (SMC) is the second largest satellite galaxy orbiting our own, smaller at the center.Image of SMC with one half This image superimposes its dark matter model (right of center). Highlight the lighter colors.density and shows a strong concentration towards the galactic center. Ninety-five percent of this dark matter is inside a circle that traces the outer edge of the model shown. In six years of data, Fermi found no indication of gamma rays from the dark matter of the SMC. (Image credit: Dark Matter, R. Caputo et al. 2016; background, Axel Mellinger, Central Michigan University)

 Dark matter 

The hypothetical particle that makes up the bulk of the mass in the universe You may not be a fan of dark matter.Its  shortcomings — and,And it's true that the dark matter hypothesis has of course, we haven't found any dark matter particles yet. But the truth is that the alternatives are much worse.

Unexplained mysteries the universe is full of  (which is what keeps astronomers and astrophysicists happily surround gravity employed), and many of those mysteries .we find that they're moving far too  As we watch stars orbit the centers of their galaxies quickly given the amount of visible matter that can keep them in those orbits with its gravity. 

Galaxies buzzing around  too quickly given the galaxy clusters also move much amount of visible mass in the clusters. Those same clusters bend background light far too much. Even the large structures quickly without an additional source of mass arose in our universe far too quickly without an additional source of mass.