Isaac Newton
"Gravity explains the motions of the planets, but it cannot explain who set the planets in motion. God governs all things and knows all that is or can be done."

January 4, 1642 - March 31, 1727


Isaac Newton was an English man who was heavily involved in the formulation of laws through his knowledge of mathematics and was a large factor in the furthering education and knowledge of astronomers to follow him. He created the law of gravitation and the laws of motion through this knowledge. He studied many aspects of light and the colors that are incorporated in sunlight. Newton used this knowledge of light to further expand on his accomplishments. He developed a reflecting telescope(2) to deal with the problems of chromatic aberration(9). He is most noted for his three laws of motion that allowed others to further understand and develop their knowledge of motion. He presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis(1)."

Newton (20)

Discovery of Gravity

The story of Newton and the apple falling from a tree brings about the idea of gravity that Newton realized after this sequence of events. The apple is accelerated as if falls towards the ground after falling off of the branch of the tree. Based on the ideas of Newton’s Laws of Motion, he realized there must be a force that acts on the apple causing it to fall off the branch and accelerate towards the ground. This force was realized by Newton as gravity. He applied this idea of gravity into explaining some of the habits of orbits of planets and objects such as the Moon falling off into its path of orbit based on gravitational forces. The picture at right shows the constant of gravity and some of the ideas Newton developed based on these observations.(6)

Reflecting Telescope

The earliest telescopes are some of those used by astronomers such as Galileo and contained glass lenses in the actual telescope in order to collect the light. What Newton realized was that many different colors of the light that entered the telescope were seen in different amounts and focused at different points in the telescope. This caused there to be a problem when viewing images in these telescopes. This idea was later defined as chromatic aberration and was a main problem with telescopes at the time. Although there was no easy fix, the telescope that Newton worked on to attempt to solve this problem had a variation of lenses to limit the light that was focused at different locations in the telescope. He used mirrors to gather the light rather than the previous use of lenses. Although Newton really wasn’t the first to come up with this idea, he made the simplest version using this method. This work of Newton was very influential because people could now view images clearer through the light gathered by telescopes. It makes telescopes light gathering power more efficient and benefits astronomy as a whole. He later expressed this idea in his work “Opticks.” (7)

Newton (7)

Laws of Motion

Newton's Three Laws of Motion are:
  1. An object at rest tends to stay at rest, and an object in uniform motion tends to remain in that state of motion, unless an external force is applied to it (the Law of Inertia).
  2. A force causes acceleration (a change in the velocity) of an object (F=ma).
  3. For every action there is an equal and opposite reaction.


Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is considered to be inertia. Constant velocity will remain if no net force does anything to the object. This means the object will remain at rest. The fact that Newton developed this idea has helped to further enhance the understanding of motion and how objects react to forces in the universe. The second law explains how the velocity of an object changes when it is subjected to an external force. The law defines a force to be equal to change in momentum in relation to a change in time. Constant mass is calculate using the mass and acceleration of that object to give you the force. The third law states that for every force there is an equal and opposite reaction. This is relatively self explanatory, but the understanding of the way in which two objects with different forces interact, helps to explain larger scale interactions in the universe. The two objects exert equal reactive forces on one another.(5)

Additional Video

Niel deGrasse Tyson back for some more. This time it's not about Pluto. Here we see how Newton gets the approval from Niel.

Works Cited

(1) "Newton's Philosophiae Naturalis Principia Mathematica (Stanford Encyclopedia of Philosophy)." Stanford Encyclopedia of Philosophy. Web. 03 Dec. 2011.
(2) "Telescopes" Wiki Page.<>.
(3) "How Did Isaac Newton Really Discover Gravity - Apple or Comet? BBC Science - YouTube." YouTube - Broadcast Yourself. Web. 03 Dec. 2011.
(4) "VideoBrief: Newton's Laws of Motion Illustrated with 3D Animations and Motion Graphics - YouTube." YouTube - Broadcast Yourself. Web. 03 Dec. 2011.
(5) "Newton." 01 Dec. 2011.
(6) "The Universal Law of Gravitation." 01 Dec. 2011.
(7) "Newton." Egglescliffe School - Home. Web. 03 Dec. 2011.
(8)"My Man, Sir Isaac Newton - YouTube." YouTube - Broadcast Yourself. Web. 03 Dec. 2011.
(9)"Chromatic Aberration." Web. 03 Dec. 2011. <>.

Kyle Mathis