What are three things that Nicolaus Copernicus invented or discovered that impact our lives today?

Nicolaus Copernicus, who lived from 1473 to 1543, was quite the rebel in his day! Copernicus lived in a time when most people believed that the Earth was the center of the universe. As an astronomer who frequently watched the skies, he didn't think this theory held up. Instead, Copernicus proposed a heliocentric theory, which held that the Sun was the center of the universe and planets orbited around it. He was almost correct! Our planet (and the others in our solar system) do, in fact, orbit around the Sun. However, the Sun is not at the center of the universe. Copernicus was the first to propose this heliocentric theory, and it has lead directly to our understanding of our solar system and the universe today.

Copernicus' heliocentric theory was proposed in his book titled On the Revolutions of the Celestial Spheres. This book went beyond simply saying that the Sun was the center of the universe, and created and justified an entirely new system of understanding the layout of our solar system. He explained that the apparent movement of the Sun in its rise and fall is not a result of any motion of our star, but actually the result of Earth's movement. Copernicus described that we experience years as a result of Earth's revolution, and we experience days (and nights) as a result of Earth's rotation on its axis. 

Copernicus also described that the apparent motions of other planets are dependent upon Earth's own motions. When we keep track of planetary motions and find that a planet has gone into "retrograde," or appears to be moving backwards or falling behind, this is the result of our own planet overtaking another in orbit. The planets do not orbit at the same speed on their various tracks, so sometimes Earth passes by another planet from a distance, creating the illusion that the planet is moving backwards.

It may seem strange to us today that Copernicus introduced all of this as new information, because we have been taught all of this as truth! In his day, it was quite shocking information and even caused some amount of scandal among the Catholic Church.