at a fun bug in Google's calculator: the parsec is wrong when you do math on it. As the earth travels around the sun, closer stars appear to shift back and forth against the far-distant background stars. The closer the star is the bigger this effect is. Think of how when you switch which eye you're looking through you notice near things shifting relative to farther ones. For example, holding up my finger I see this out of my right eye: But this out of my left eye: If a star moves by two arcse...

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