What technical difficulty did Hubble overcome when observing variable stars within M31?
Answer
Isolating faint, periodic flicker against the collective glow of billions of stars.
Hubble's observational achievement involved overcoming an extreme technical hurdle related to signal isolation. He was tasked with finding the faint, periodic flicker of an individual Cepheid variable star against the overwhelming, constant background glow produced by the billions of other stars packed closely together in the dense core of the Andromeda galaxy. Successfully tracking the light curve and establishing the period of these faint variables required painstaking observation and immense precision to differentiate that single, subtle flicker from the collective stellar light pollution.
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