• Kongar@lemmy.dbzer0.comEnglish
    3·
    6 days ago

    I mean that’s cute but not quite correct right? Depends on their distance from you I think. A very very long distance.

    • Contramuffin@lemmy.worldEnglish
      18·
      6 days ago

      You’re confusing 2 different but related concepts. Blueshift and redshift does depends only on velocity. In the cosmological sense, redshift (the opposite of blueshift) occurs because everything is moving away from everything else due to the expansion of the universe, and so the distance of an object can be calculated based on how much redshift there is in the light. Basically, on a cosmological scale, distance and velocity are connected

      • Kongar@lemmy.dbzer0.comEnglish
        5·
        6 days ago

        Right, I was thinking of redshift. But now I’m even more intrigued. How does a thing moving toward me shift light blue? It’s not like the space inbetween us is shrinking…. And the speed of light is constant…

        What the heck is blue shift? I need to go hit Google/wikipedia/something smarter than me ;)

        • protist@retrofed.comEnglish
          10·
          6 days ago

          The speed of light is constant, however the frequency of light is variable. Similar thing with sound, high pitched and low pitched frequencies travel at the same speed in the same medium

          • Crazyslinkz@lemmy.worldEnglish
            1·
            5 days ago

            Yes! Ever heard a car horn coming at you and then going away? It’s the wave compressing and expanding.

        • Elting@piefed.socialEnglish
          6·
          6 days ago

          Red shift and blue shift are exactly the same thing. If you think about light as a wave, like sound, approaching objects have scrunched up waves (blueshifted light) and fleeing objects have spaced out waves (redshifted light). The exact same reason a car horn has higher pitch when it is approaching you and lower pitch when it travels away. The intensity of the effect is correlated to the speed limit of the medium so since light is so fast this effect is typically very small.

        • Kongar@lemmy.dbzer0.comEnglish
          6·
          6 days ago

          Interesting, the interwebs just taught me that redshift does occur like the Doppler effect. Similarity blueshift in the other direction. I always thought it was just from space expanding.

          You learn something new everyday!

    • Elting@piefed.socialEnglish
      6·
      6 days ago

      The doppler effect you can hear when something loud passes you happens to light too. It would have to be aproaching very fast indeed however to make a red rose appear blue. (Like fast enough to fuse atoms in the atmosphere)

      • Kongar@lemmy.dbzer0.comEnglish
        2·
        6 days ago

        Thanks! I just learned this - makes sense at fast speeds. Just never thought it was from anything other than space expanding :)

    • Draconic NEO@mander.xyzEnglish
      1·
      5 days ago

      Doppler shift is based on relative velocity, the result of red shift is that stuff which is moving away fast enough to produce red shift is far away by virtue of being fast and stuff and stuff that is blue shifted needs to be far away or it will collide with you very quickly or just pass you by. The relative velocities required for doppler shift are pretty high speeds so you normally observe it in stuff that’s far away, but distance isn’t really a requirement for doppler shift to happen or be observed.