This background radiation or CMB (cosmic microwave background) is the absolute reference against which to measure velocities in our Universe. It looks like these are the major clusters of galaxies to which our Milky Way Galaxy is gravitationally attracted, and it causes our Galaxy to move at around 600 km/sec with reference to the microwave background radiation. The most important gravitational attractions that cause our Galaxy to move even faster is the Great Attractor (a large collection of galaxies) and the much more awe-inspiring Shapley Supercluster of galaxies. At a small scale we are attracted to the Andromeda galaxy and are on a “collision” course with it (Of course we won’t collide because galaxies are way too diffuse so to speak). The important thing about the motion of our Milky Way in the Universe is simply gravitational attraction among galaxies and clusters of galaxies that causes movement. In this frame, the Local Group that the Milky Way is a part of moves with some $620\, \mathrm$. Any reference is valid, but it makes sense to use the frame in which all galaxies are, on average, in rest (when the Hubble flow is subtracted) $^\dagger$. One may define a "global reference frame" with respect to which velocities are measured. But this is not a motion through space rather it is space itself that is expanding (and hence the velocity may exceed the speed of light for sufficiently large distances). In addition to this so-called "peculiar velocity", galaxies also also carried away from each other due to the expansion of the Universe, at a velocity proportional to the distance from each other (the " Hubble flow"). 2000) and large velocities for rich clusters (~1000 km/s e.g Girardi et al. Galaxies move through space with velocities of the order of a several 100 km per second small velocities for small groups (~100 km/s e.g Carlberg et al. And the motion of galaxies isn't neat and tidy either. (See the Wikipedia Galactic Year article). Hopefully the question makes sense, if not I can elaborate.Įdit : as Dave points out in the comments, there are other motions, including the motion of the solar system around the galaxy, which is circa 514,000 mph. Perhaps it's because the Universe is full of things moving in fairly random directions. Or does it stay in a single location? If it does move, what causes it to move? Also see the CMBR physics answer by ghoppe which talks about the CMBR reference frame, which is in effect the reference frame of the universe. The speed of light is just under 300,000 km/s or 670 million miles per hour, so the Milky Way is moving through the Universe at circa 0.2% of the speed of light. See this article, which says it's 1.3 million miles an hour. This motion results in an anisotropy of the data (CMB appearing slightly warmer in the direction of movement than in the opposite direction)."Ħ27 km/s is quite fast. "From the CMB data it is seen that the Local Group (the galaxy group that includes the Milky Way galaxy) appears to be moving at 627☒2 km/s relative to the reference frame of the CMB (also called the CMB rest frame, or the frame of reference in which there is no motion through the CMB) in the direction of galactic longitude l = 276°☓°, b = 30°☓°. Kinney's Cosmology, inflation, and the physics of nothing When we look at the Cosmic Microwave Background Radiation we see a "dipole anisotropy" due to the motion of the Earth relative to it: One thing I ask myself is if our galaxy moves through space? I'm very fascinated with space, although I don't have a degree or any formal education, I'm still very in love with everything about it and want to learn constantly.
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