The first scientifically minded celestial observers included people such as Nicolaus Copernicus (1473–1543), Johannes Kepler, and Galileo Galilei, who began looking at the sky through telescopes they built. Galileo’s view of Jupiter in 1610 transformed our view of the planets. They weren’t just dots of light in the sky. They were worlds. Over the years, more and better telescopes have revealed double stars and nebulae in the sky, and their discoverers set out to figure out what these things were. The science of “natural philosophy” uses mathematics, chemistry, and physics to explain objects and events in the universe. Nicolaus Copernicus came up with the heliocentric solar system, with the planets orbiting the Sun. The laws of planetary motion developed by Johannes Kepler and the laws of physics devised by Sir Isaac Newton helped explain the motions of bodies in space.

Contributions of Famous Scientists and Breakthroughs:

Nicolaus Copernicus – He wrote De revolutionibus orbium coelestium(on the revolution of the heavenly sphere)(1543) in which he proposed the heliocentric theory.

Galileo Galilei– He was the first one to look at the sky with a telescope. In 1610, with a telescope, he watched Jupiter and discovered 4 moons(Galilean moons). He also observed phases of Venus and sunspots. He wrote On motion , Dialogue concerning the two chief world systems and  Discourses and mathematical demonstrations relating to two new sciences .

Hans Lippershey and Zacharlas Janssen (dutch-german opticians)- They invented the telescope(first to patent)

Johannes Kepler – He wrote Mysterium cosmographicum (latin for the cosmographic mystery)(1596) in which he defended copernican heliocentric ideas. In 1609, he published the first 2 laws of planetary motion. 

Kepler’s laws: 1. The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus.

2. An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time.

3. The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their semi-major axis.

Kepler’s Publications- Johannes Kepler published treatises about many topics. Here is a list of some of his other astronomy-related works.

1. Astronomia Pars Optica (Optics in Astronomy)

2. Astronomia Nova (The New Astronomy) 

3. Dissertatio cum Nuncio Sidereo (Conversation with the Starry Messenger, an endorsement of Galileo Galilei’s observations)

4. Harmonice Mundi (The Harmony of the Worlds, in which Kepler describes harmony and congruence in geometry and presents his third law of planetary motion)

William Herschel– He deduced that the solar system is  moving, and saw martian ice caps. He created a deep sky catalog and double star catalog and catalogue of 500 nebulae, nebulous stars, planetary nebulae,etc. He discovered uranus (1781). He also discovered infrared light.

Caroline Herschel- she was the first woman paid to do astronomy and she discovered 8 comets.

John Federick William Herschel- He published the general catalog of 10,300 multiple and double stars, and The New General Catalog of Nebulae and Clusters(NGC).

Isaac Newton– He gave the famous three laws of motion. 1.The first law states that an object at rest will stay at rest, and an object in motion will stay in motion unless acted on by a net external force.

2]The second law states that the rate of change of momentum of a body over time is directly proportional to the force applied, and occurs in the same direction as the applied force.

3]The third law states that all forces between two objects exist in equal magnitude and opposite direction.

He also gave the universal law of gravitation. He invented Newtonian reflectors- telescopes with reflecting mirrors.

Henrietta Swan Leavitt– She discovered cepheid variables(period of pulsation of star is related to intrinsic brightness of star), many other variable stars and novas.

Edwin Hubble– He showed that the universe was larger and beyond the Milky Way by showing that Andromeda was outside the milky way. He discovered the universe is expanding. He gave the hubble sequence of galaxy morphologies – spiral, elliptical, lenticular or irregular.

Einstein– He discovered the photoelectric effect, and  wave-particle duality. He published the special theory of relativity and the general theory of relativity.

Jocelyn Bell burnell– The first pulsar that Bell found is called PSR 1919+21, and its signal repeats precisely every 1.33 seconds.It was called LGM-1. 

Vera Rubin– She proved the existence of dark matter.

Clyde Tombaugh – In 1930, He discovered pluto.

Mike brown– He demoted Pluto to dwarf planet and wrote How I Killed Pluto and Why It Had It Coming. 

https://en.wikipedia.org/wiki/Newton’s_laws_of_motion
https://en.wikipedia.org/wiki/History_of_astronomy