If you’ve ever heard of the Kepler Telescope, it should come as no surprise to learn that it’s named after an astronomer. The Kepler Telescope is involved in the search for habitable planets beyond our solar system — but why would it be named after an astronomer who was born in 1571?
Johannes Kepler was lucky enough to be taught by some of the greatest astronomers of his time. In return, he discovered three major laws regarding how planets move. In Kepler’s lifetime, the Earth was considered the center of the universe and the planets moved in perfect circles. Kepler was about to prove those last two ideas wrong, all before the invention of the telescope.
Kepler’s Laws of Planetary Motion
Kepler’s most notable contributions to astronomy concerned how the planets move. However, Kepler didn’t look at this from a scientific viewpoint — at least, not in the way we’re used to today. Back then, science was all mixed up with religion and fortune telling, so it’s no real surprise that Kepler viewed his new laws through a religious lens. He was a deeply spiritual man, and viewed his discoveries as proof of God’s existence.
Kepler was heavily influenced by Nicolaus Copernicus. If that name sounds familiar, it’s because Copernicus is traditionally credited as the first person to propose the idea of a heliocentric universe, instead of the popular geocentric model. This was met by outrage from the public, and from the church, which was the main ruling body at the time. The Greek philosopher, Philolaus, actually proposed the idea first. Both Copernicus, and later Kepler, referenced the work of Philolaus to prove their heliocentric theories.
There were three laws that Kepler discovered, but he never would have made these breakthroughs if he hadn’t followed the model Copernicus laid out. He discovered the Law of Orbits, which states that the planets move in ellipses, instead of circles. He also discovered the Law of Areas, stating that an imaginary line connecting the Sun and a planet will sweep out an equal area of space in an equal amount of time.
Lastly, he discovered the Law of Harmonies. This is a more complex law, based on calculations that are more difficult to explain. It states that the period of a planet’s orbit can be used to determine the planet’s distance from the sun. The equation is P2 = a3, where P is the period and a is the size of the orbit.
Strange, New Ideas
As you may have noticed, many of Kepler’s discoveries can be derived mathematically, instead of just through observation. Part of this is because, as a child, Kepler suffered from smallpox. The disease left him mildly crippled from a physical standpoint, which limited his ability to work with observational data. It failed to affect his mind, however, and he continued to make great use of that!
One of the ideas Kepler had was a kind of rudimentary idea of gravity. He held an unshakable faith in God, but was working on rejecting the notion that individual souls pushed the planets or that the sun was a static figure. Instead, he thought that the sun exerted a single force that was responsible for longer periods as the planets got further away.
Another astronomer, William Gilbert, came up with the idea of the Earth acting as a kind of magnet, and Kepler jumped on it. He proposed that not only the Earth, but all the planets, as well, were magnets, repelling like forces and attracting opposite ones. As such, the Sun attracted the planets while the planets repelled each other, causing the orbits. This lay the groundwork for Isaac Newton to discover the Law of Gravity.
An Eventful Life
Even though Kepler gained fame in his lifetime as a renowned astronomer, and despite his unshakable faith, his life was not an easy one. In sharp contrast to his personal beliefs, Kepler’s mother, Katharina Kepler, was seen as a witch. She collected herbs and worked hard to make sure Kepler loved the natural world as she did.
By taking him out late at night, his mother helped expose him to natural phenomena that sparked his interest in astrology. One such event was a comet in the night sky, and another was a lunar eclipse. At one point, Kepler was forced to act as her lawyer to keep his mother from being sentenced to death as a witch due to her eccentricities.
One thing that continues to haunt Kepler’s reputation is the fate of another astronomer, Tycho Brahe. In contrast to Kepler’s calculations, Brahe worked mostly on direct observation. The pair worked together for a time at Brahe’s observatory. However, soon after joining his team, Brahe died.
Kepler jumped at the chance to gain access to Brahe’s work. This, clearly, did not look good. In hindsight, there are some who think he might have had a hand in Brahe’s death. There is little actual evidence to support this, however, and Kepler did admit that taking advantage of the situation was a mistake. Eventually, Brahe’s name was restored to his work, and Kepler returned to focus on his own calculations.
Despite his humble beginnings, Johannes Kepler’s legacy is anything but modest. Having discovered three Laws of Planetary Motion, and almost discovering the Law of Gravity, it’s impossible to argue that he wasn’t brilliant. His legacy lives on, searching the heavens above for new, habitable planets.