galaxy cluster
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How Massive are Galaxies?
If you needed to measure the mass of, say, a brick — or some other Earthly object — you could just set it on a scale. (Yes, scales measure mass, not weight.) With galaxies, it’s not so easy! I don’t…
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How Far Away are Galaxies?
Well, I’ll give you a spoiler: they’re ridiculously far away. Let’s consider for a moment what a light-year actually means. It sounds like a unit of time, but it’s actually the distance that light travels in one Earth year. Think…
