Questions tagged [definition]

Questions targeting the exact (possibly mathematical) description of a phenomena or term.

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What is the difference between spectroscopy, spectrography and spectrometry?

Spectroscopy is the study of spectra, spectrography is the writing of the spectra, and spectrometry is the measure of spectra. So from an etymological perspective, there is no real difference between ...
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What are Euclidean-normalized differential source counts?

I would like to know what the Euclidean-normalized and differential source counts mean in "Euclidean-normalized differential source counts". It would be great to hear a) a clear definition ...
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When and why was zero right ascension defined to be at the vernal equinox?

When (and why) was zero right ascension defined to be at the vernal equinox? Who established or defined this standard?
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How close must a full moon be to become a supermoon?

According to this answer there is a scale of super moons depending on how close the full moon(henceforth anti-sol) is to perigee. So how close to anti-sol does the moon's perigee need to be to be ...