3 Measured and Discovered By the Doppler Effect
In order to find the Black hole, Astronomers used the special Doppler Effect to map gases known to surround black holes. The Doppler Effect maps the changes of different frequencies of sound, light or any other existing waves, In the case of the super massive black hole.
Astronomers studied frequencies of radio waves emitted from the carbon monoxide molecules presented in the gas cloud. Such emissions are bright enough for Alma to detect. The results of the discovery were published in the Astrophysical Journal of letters. Watch the incredible video.