Describe henrietta leavitt's discovery, and explain why it was so important in the society in which she lived.

Henrietta Swan Leavitt discovered cepheids in 1908 during the investigation of different stars in the clouds. She published it by working more on it in 1912 and died in December 1921. This discovery was so important in the society in which she lived because the cosmologist of America was known for this discovery of Cepheids which is a relationship between period, luminosity and quivering stars which changes in light.

they are known to reach a speed of 21 miles per hour

i believe the answer is a or 1