Galileo was born in 1564 AD and died in 1642. His father was a mathematician. He prevented the boy from knowing that the subject existed. At the age of 19, he overheard a Geometry lecture which enlightened him. Galileo Galilei received a broad Renaissance education. Until 1610, when Galileo built his first telescope at age 46, he focused mainly on physics, not astronomy.
He soon made discoveries which shook the foundations of the Aristotelian cosmos. He was a professor at Pisa. His main contributions were on astronomy. He was a genius of the following:
1. He discovered the telescope, a practical instrument.
2. He attributed to the opinion of Copernicus.
3. He created a foundation of general belief.
4. Was the first man to combine experimentation with mechanical skills.
5. He started the study of dynamics-laws governing movement of bodies.eg. a body in motion keeps on moving in a straight line with uniform velocity if it is free from external influences.
6. Discovered that bodies fall vertically with uniform acceleration at 10m/s.
7. Discovered that when a body moves in a horizontal direction, it moves in a parabola.
8. Started the use of experiments to derive mathematical laws.
9. He reinvented a Telescope which had been invented by a Dutchman.
Through the telescope, he came up with new discoveries:
a) He discovered the existence of Jupiter’s satellites. He observed the motion of four of Jupiter's moons, now referred to as the Galilean moons.
b) He discovered that the moon has mountains.
c) He saw mountains, valleys and other features indicating change on the moon.
d) No longer could scientists say that heavenly bodies revolve exclusively around the earth.
e) He also observed the phases of Venus, the only explanation of which is that Venus moves around the sun and not the earth.
f) He discovered four more planets- Apart from the seven heavenly bodies discovered by Aristotle ( the sun, the moon and the five planets)
g) He discovered that the sun has spots ( theologians saw that he was saying the creator has blemishes).
h) He discovered that Venus had phases like the moon.
PHASE-ASTRONOMY recurring shape of moon: a recurring form of the Moon or a planet seen in the sky.
The four principal phases of the Moon are the first quarter, full moon, last quarter, and new moon
i) he supported and proved correct the Copernican theory.
The support for Corpenican theory started a controversy between him and the church. He was advised by the clergy to stop defending the opinion instead he should take the Copernican theory as a calculated device but not the two theories of the universe.
In 1630, Galileo visited the Pope to obtain the permission to publish his book. The Pope accepted but gave him the following conditions:
a) The title must indicate what’s in the book.
b) The subject must be treated from a theoretical point of view.
c) The book must terminate the argument that tides can’t be abducted as a necessary rule of the motion of the earth.
Galileo published his book; however, he did not leave out the ideas of Copernicus. He discovered the stars and planets and habitability of the moon. The idea of the habitability of the moon and other planets annoyed the church.
Wilfykil answered the question on March 1, 2019 at 12:21