Which naked-eye star is richest in metals and what is the estimated mass of the metal contained therein? ThomasMineral, Virginia In astronomer-speak, metals refer to elements heavier than helium. The first stars that lit up the universe were very metal-poor, since hydrogen and helium were just about the only materials around after the Big Bang. TheseContinue reading "Which naked-eye star is richest in metals?"

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Why does one side of the Moon have a lot of craters, while the other side does not? Stephen LogesBrooksville, Florida When the first photos of the Moon’s farside were obtained, people usually expressed the difference between the back and the front in terms of “more craters on the back.” It might be better toContinue reading "Why does one side of the Moon have a lot of craters, while the other does not?"

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Occasionally I see references in Astronomy to the speed of something as “supersonic.” I’m having trouble reconciling this term with velocities typically found among astronomical objects. Wouldn’t “relativistic” be closer to the truth? Anything close to sonic speeds in Earth’s atmosphere wouldn’t cover much distance in outer space. Peter IanchiouTucson, Arizona One would certainly thinkContinue reading "What does the term ‘supersonic’ mean in astronomy?"

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