The first person to provide observational evidence for expansion was American astronomer Vesto Slipher, who used the spectra of stars to measure the velocities of nearby galaxies.

• 第一位提供宇宙膨胀观测证据的人是美国天文学家斯里佛（VestoSlipher），他利用恒星光谱来测量邻近星系的速度。