Question

question 41
a standard candle (or standard bulb) is
a light source of known brightness
a name for a main - sequence star
a name for a barred spiral galaxy
a 10 - cm wax candle or 15 watt bulb powered by a aaa battery

Explanation:

A standard candle is an astronomical object whose intrinsic brightness is known. This allows astronomers to calculate distances based on how dim the object appears from Earth.

Answer:

A. a light source of known brightness