History and Theories of Astronomy Flashcards
Nicolaus Copernicus
Widely credited as the father of the heliocentric theory. Although he was not the first to propose the concept, his was the first mathematical model which correctly predicted the movement of the planets. He later published a book which was instrumental in making the idea popular.
Hans Lippershey
Usually credited as the inventor of the telescope (though it wasn’t called that for many years later). He was a German-Dutch lens maker who first applied for the patent of the “Dutch Perspective Glass”. It is important to note that, at the time, these were not used for astronomy. That came a little later with Galileo.
Galileo Galilei
Was the first to use a telescope for astronomical studies. He later used that telescope to discover the four largest moons of Jupiter. Galileo was as a firm believer in the heliocentric theory. Since most scientists of the time and, more importantly, the Church embraced the geocentric theory, this caused Galileo much trouble and was the reason he was later placed under house arrest until his death.
Celestial Sphere Theory
In the early days of Astronomy, there were, plenty of theories like the geocentric theory which were later disproven. Another of these theories was something called the celestial sphere theory. This theory said that what we see in the sky was actually numerous spheres. You can think of the spheres as clear globes around Earth with planets, comets and stars inside each of these globes. Some of these were thought to be in our own atmosphere and others were farther away. Even Copernicus, who got it so right with the Heliocentric theory, still believed in these celestial spheres. For example, his model of the universe had the stars at equal distance from the earth in one of the most distant spheres.
Tycho Brahe
Disproved the celestial sphere theory that all celestial objects were unmoving objects in Earth’s sky. He demonstrated this was untrue through observation of a supernova, which he proved was beyond the solar system and thus not a phenomenon within Earth’s atmosphere.
Johannes Kepler
Johannes Kepler was a mathematician who proposed the three Laws of Planetary Motion. These stated that the planets move in an elliptical orbit around the sun and mathematically showed how it was possible. Kepler’s laws provided the building blocks for many theories to follow.
First Law of Planetary Motion (The Law of Ellipses)
This law says that the planets orbits are elliptical in nature and that the center of the sun is a focus for those ellipses.
Second Law of Planetary Motion (The Law of Equal Areas)
This law describes how fast the planets are moving around the sun. The closer the planet gets to the sun, the faster it goes. As it moves farther away from the sun, it will slow down. However, the second law also says that if we drew a line from the center of the sun to the center of the planet, we would see that every 31 days the area covered by that line would be the same. Hence the name – “Law of Equal Areas.”
Third Law of Planetary Motion (The Law of Harmonics)
The third law of planetary motion says that the orbital periods of different planets are related. Specifically, that the ratio of the squares of the orbital periods to the cubes of the average distance from the sun are the same. In other words – You take the length of time the planet takes to complete an orbit around the sun and square that number. You then take the planet’s Average Distance from the sun and “cube it. The ratio between those numbers will be the same no matter what planet you use the formula for.
Isaac Newton
He invented the first functional reflective telescope. Newton also proposed the three laws of motion and the law of universal gravitation.
First Law of Motion
This law states that an object at rest will stay at rest unless acted upon by an outside force. Likewise an object in motion will not change its velocity unless acted upon by an outside force. This is also called the Law of Inertia.
Second Law of Motion
This law states that an object’s mass is directly proportional to how much force is going to be needed to move that object. In other words, pushing a large box of tissue paper is going to be much easier than pushing an equally large box of rocks. The box of rocks has a much larger mass than the box of tissue paper, even though they are the same size. Newton’s second law provided a formula to determine just how much force was needed in order to accelerate an object based on its mass.
Third Law of Motion
This law states that to every action there is always an equal and opposite reaction: or the forces of two bodies on each other are always equal and are directed in opposite directions.
Law of Universal Gravitation
States that everything in the universe has a gravitational field that affects other objects, and how strong that field is depends on the object’s mass and how close the two objects are to each other.
Max Planck
German scientist who worked with Albert Einstein and is generally credited with creating Quantum Mechanics. His Quantum Theory revolutionized natural science and was the reason he was awarded the Nobel Prize in 1918. Quantum Mechanics deals with matter on the atomic and sub-atomic level and is used in Astronomy to explain the behavior and existence of many cosmic bodies which would otherwise be difficult to explain using normal physics.
