If Subrahmanyan Chandrasekhar were still alive he would be celebrating his 107th birthday. The astrophysicist and subject of Thursday’s Google Doodle, was the first astrophysicist to ever win a Nobel Prize, studied the evolution of stars during his years of research. He was one of the first researchers and scientists to study both astronomy and physics together, according to NASA.

Chandrasekhar was a child prodigy who published his first paper on the theory of star evolution in the 1928, before he even turned 20 years old. The theory was revolutionary and met with skepticism. During his years of research he developed theories on everything from star atmospheres, black holes and star structure and mass. He came up with the upper limit of the mass of a white dwarf, named the Chandra limit, after him. This is the limit of mass a star can have and still become a white dwarf when it dies, if a star has a mass above the limit, it will become a black hole as it dies.

Today's Google Doodle illustrates the Chandra limit one of Chandra's most important theories. It shows a balance scale with a weight of 1.44 on one side, representing 1.44 times the mass of the sun. On the other side a star drops in, but weighs less than 1.44 times the sun, so it does not tip the scale. This star would be a white dwarf as it died. But the star that follows it weighs more than 1.44 times the sun, and tips the scale. This star would be a black hole as it died.

The Doodle will appear on Google homepages in the United States, Australia and select countries across Europe, South America, Africa and Asia. “Today we honor the original starman whose universal theories propel current space research and modern astronomy on their ambitious missions,” said the description of the Doodle from Google.

Google has been putting Doodles on the homepage for nearly two decades now. It started with a Doodle about Burning Man and eventually turned into a regular change to the site’s usual look. Now there’s an entire archive of every Doodle that’s ever been on the site. Anyone can search a date, person or event to find whether there’s been a Doodle honoring it. There’s a team of Doodlers who decide which events, holidays or people to honor and work up the animation or game for that date.

Once a year a Doodle designed by a student is featured on the site. There’s a Doodle 4 Google competition that students from various grade levels across the country can submit Doodles to.