Another Important Scientist - Still More Questions

In our past lesson we learned of many ancient astronomers. Galileo Galilei supported Nicolaus Copernicus' theory that the sun is at the center of the solar system. Using a telescope Galileo was able to make observations, including phases of Venus and moons around other planets. Galileo had recorded an additional observation. He discovered that a moving object will continue to move until some force acts to stop its motion. This tendency of a moving object to continue in a straight line or a stationary object to remain in place is the object's inertia. The more mass an object has, the more inertia it has.

Isaac Newton

Isaac Newton was an English scientist who provided the answer to the question - How do the planets stay in their orbit?

Newton took Galileo's observations on inertia and figured out that the Earth is pulling the moon toward it with gravity.

Gravity - The force that pulls an apple to the ground, pulls the moon toward Earth, keeps the planets in orbit and attracts objects towards each other.

Newton deduced the planets in our solar system are drawn to the gravity of the Sun, which keeps our Earth and the other planets orbiting around the Sun.

Learn more about gravity by watching the video below. Be patient it may take a few moments to load the video.

Newton's First Law of Motion

Says that an object at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted on by a force.

Galileo took the ideas of another scientist to create his own telescope. He also read Copernicus writing with his theory of a heliocentric solar system. Kepler learned from Brahe to discover elliptical orbits of planets. How important is it for scientists to share their observations and theories?

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