What are the two theories about galaxy?
In the absence of direct evidence, astronomers formed two theories: the theory of accretion, in which blobs of stars came together to form galaxies; and the theory of collapse, in which galaxies were formed in the collapse of an enormous gas cloud.
Is the Milky Way galaxy a theory?
Many astronomers believe that a massive collision formed the Milky Way, shaping it into the spiral galaxy it is today. A popular theory suggests that around 11 billion years ago, a small galaxy called Gaia-Enceladus slammed into the primordial Milky Way.
What are the 4 types of galaxies and theories of their origins?
There are four main categories of galaxies: elliptical, spiral, barred spiral, and irregular. These types of galaxies are further divided into subcategories while at the same time other types of galaxies exist based on their size and other unique features.
How did our Galaxy form and evolve?
In the simplest telling, it held that our Milky Way galaxy came together nearly 14 billion years ago when enormous clouds of gas and dust coalesced under the force of gravity. Over time, two structures emerged: first, a vast spherical “halo,” and later, a dense, bright disk.
What is galactic evolution?
What is Galactic Evolution? On a clear night, you can make out the band of the Milky Way in the night sky. For millennia, astronomers looked upon it in awe, slowly coming to the realization that our Sun was merely one of billions of stars in the galaxy.
How did galaxies evolve into different structures?
“Galactic Mergers: Once formed, these galaxies evolved together in larger galactic structures called groups, clusters and superclusters. Over time, galaxies were attracted to one another by the force of their gravity, and collided together in a series of mergers.
How are galaxies attracted to one another?
Over time, galaxies were attracted to one another by the force of their gravity, and collided together in a series of mergers. The outcome of these mergers depends on the mass of the galaxies in the collision. Small galaxies are torn apart by larger galaxies and added to the mass of larger galaxies.
How do small galaxies become large galaxies?
Small galaxies are torn apart by larger galaxies and added to the mass of larger galaxies. Our own Milky Way recently devoured a few dwarf galaxies, turning them into streams of stars that orbit the galactic core.