Turns out that stars really twinkle and it’s not just an optical illusion we get here on Earth.  The first variable star was discovered by David Fabricus in 1596 and is now called Mira.  Mira was later discovered to have an 11 month variability by Johannes Holwards in 1638.  This discovery along with the discovery of supernovas paved the way for astronomy.

Betelgeuse, discovered in the 1830’s by John Herschal, is a variable star.  His four year research of the changing brightness of Betelgeuse sparked the study of astrophysics.