When you look into a star-filled night sky, you see what Tycho Brahe — a noseless Danish aristocrat — saw.

Only he saw it better.

Tycho goes by one name, like Copernicus, Kepler and Galileo. He died in 1601, nine years before Galileo turned a telescope on the moon and changed everything.

So Tycho stands as the last great naked-eye astronomer — maybe the greatest — and one of the essential founders of the science of astronomy.

“He looked up into the sky and asked ‘What’s up there?,’ ” said Monty Robson, director of the John J. McCarthy Observatory in New Milford, who spoke there this month about Tycho’s achievements.

“He was significantly important for more than one reason,” said Diana Hannikainen, observation editor for Sky and Telescope Magazine. “He was the first to study the sky systematically.”

And science, like everything, has a history. Tycho is part of it.

“I don’t think people understand that,” Robson said. “We stand on the shoulders of giants.”

And unlike his more scholarly counterparts, he led a grand life.

He was born in 1546 in Denmark to a family of noble blood and many titles. As a university student, he studied first in Copenhagen, then throughout Europe — in Leipzig, Rostock, Wittenberg and Basel.

“He had a superb education,” Robson said.

It was in Rostock in 1566 that he fought a duel that ended up with his opponent cutting off much of his nose. For the rest of his life, he wore a prosthetic nose — of brass, or gold or silver, depending on the occasion — which he stuck to his face with adhesive gel. Among famous astronomers, he is the only one with a famous nose.

Tycho’s first great — even revolutionary — discovery came in 1572, when he saw a supernova, a bright stellar explosion in the constellation Cassiopeia. Using the simple astronomical instruments of the day, he was able to accurately measure its position in the sky and prove, definitively, that it was a new object.

Until that point, standard teachings — passed down from Aristotle and Ptolemy — were that all stars in the sky were fixed, and the universe, unchanging.

“Then, gosh, things were not fixed,” Hannikainen said.

Five years later, Tycho observed the Great Comet of 1577. Until then, astronomers thought comets were a sort of floating atmospheric disturbance, full of portents. Tycho was able to show the comet was a physical object moving far outside the orbit of our moon. It was, like the supernova, something new.

From the 1570s to 1597, Tycho lived on the island of Hven, off the coast of Denmark. With the blessing of, and the money from, King Frederick II of Denmark, Tycho built Uraniaborg, named after Urania, the daughter of Zeus and the muse of astronomy. It was the first great observatory in Western history.

The Uraniaborg estate included a castle, laboratories, an observatory, gardens and orchards — Tycho was an alchemist, apothecary and an herbalist as well as an astronomer. He built some of the best astronomical instruments of the day and with his assistants, including his sister Sophie, he began to systematically study the stars and planets, night after night for more than 15 years. He observed. He measured. He gathered data like no one before him.

This month, St. John’s College in Santa Fe, New Mexico, unveiled a working recreation of one of Tycho’s instruments — an armillary sphere, which consists of four beautiful interlocking stainless steel rings and a sliding viewfinder.

Mark Rollins, a tutor at the college, said the armillary sphere is in keeping with the college’s mission to see science and the humanities as whole.

“It’s a scientific instrument that’s also a work of art and a part of history,” Rollins said.

One of Tycho’s last assistants, Johannes Kepler, used Tycho’s data about the orbit of Mars to formulate his three great laws of planetary motion, Rollins said. In turn, Sir Isaac Newton used Kepler’s work as a starting point for his groundbreaking theories on the laws of mechanics and gravity in his Principia Mathematica in 1687.

Tycho died in Prague in 1601. The story is this: He was at a banquet held by his new patron, the Holy Roman Emperor Rudolph II. Tycho drank copiously, but according to court protocols, he could not get up to relieve himself until Rudolph stood first. While waiting, Tycho’s bladder burst. He died 11 days later.

“He died because he had good manners,” Robson said.

Contact Robert Miller at earthmattersrgm@gmail.com