3 ms·
Better comparison, the furthest visible galaxy is at 13B LY. Therefore it's like at 20% distance towards the visible universe's edge.
by habibur 4y ago
Better comparison, the furthest visible galaxy is at 13B LY. Therefore it's like at 20% distance towards the visible universe's edge.
- panzi 4y agoThe observable universe is roughly 90B LY in diameter, which factors in how much the universe expanded the source of the light (or rather radio signal) away since its emission.
- mr_mitm 4y agoAt this scale, you have to specify which distance measure you are using. I can infer that you mean light-travel distance, but a cosmologist would use the comoving distance unless specified otherwise. That's what the other comment was getting at with the 90B light-years and the observable universe. Reference: https://en.wikipedia.org/wiki/Distance_measure https://en.wikipedia.org/wiki/Distance_measure
- habibur 4y agoDistances of stars and galaxies are mostly always put in light travel distance -- that was my assumption. Unless that's changed in recent times.
- mr_mitm 4y agoIn articles for the general population, you're right in both cases. For stars, you are also right in general. Well, we'd both be right, because for pretty much all observable stars light travel distance and comoving distance are equal (doesn't really make sense to talk about comoving distances or cosmological redshifts within a galaxy). In scientific populations, distances to galaxies are always given either directly in redshifts or perhaps in special cases in comoving distances.