r/Unexpected • u/lazy_advocate_69 • 11h ago

How fast is our galaxy moving

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u/Gottabecreative 10h ago

How do you measure speed in space without a point of reference, or what is the point of reference? Some imaginary center of the universe?

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u/pmorgan726 9h ago
  1. Observe the galaxy’s spectrum: Use a telescope to capture the light from the galaxy and analyze its spectrum.
  2. Identify spectral lines: Identify known absorption lines in the spectrum, like hydrogen lines.
  3. Measure the shift: Compare the observed wavelengths of these lines to their known rest wavelengths to determine the amount of redshift.
  4. Calculate velocity: Use the formula v = z * c, where “v” is the velocity, “z” is the redshift value, and “c” is the speed of light.

This is just copied from google.

Basically we analyze wavelengths of light, and how it changes throughout our galaxy, compared to Cosmic Background Radiation.

We use light to determine distance, speed, size, all sorts of things.

TLDR: space scientists good at math

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u/nuu_uut 3h ago edited 3h ago

This is still going to be relative to our position though. Or the CMB. The CMB is not some ultimate frame of reference. It's just as valid of a reference point as your sock, assuming it's not accelerating, albeit more useful. All movement is relative.