His laws changed all of physics and astronomy. His laws made it possible to calculate the mass of the sun and planets. The way it's done is immensely beautiful. If you know the orbital period of any planet, say, Jupiter or the Earth and you know its distance to the Sun; you can calculate the mass of the Sun. Doesn't this sound like magic?

We can carry this one step further - if you know the orbital period of one of Jupiter's bright moons, discovered by Galileo in 1609, and you know the distance between Jupiter and that moon, you can calculate the mass of Jupiter. Therefore, if you know the orbital period of the moon around the Earth (it's 27.32 days), and you know the mean distance between the Earth and the moon (it's about 200,039 miles), then you can calculate to a high degree of accuracy the mass of the Earth.

… But Newton's laws reach far beyond our solar system. They dictate and explain the motion of stars, binary stars, star clusters, galaxies and even clusters of galaxies. And Newton's laws deserve credit for the 20th century discovery of what we call dark matter.

His laws are beautiful. Breathtakingly simple and incredibly powerful at the same time. They explain so much and the range of phenomena they clarify is mind boggling. By bringing together the physics of motion, of interaction between objects and of planetary movements, Newton brought a new kind of order to astronomical measurements, showing how, what had been a jumble of confused observations made through the centuries were all interconnected.

Related Quotes

Newton supposed that the case of the planet was similar to that of [a ball spun around on the end of an elastic string]; that it was always pulled in the direction of the sun, and that this attraction or pulling of the sun produced the revolution of the planet, in the same way that the traction or pulling of the elastic string produces the revolution of the ball. What there is between the sun and the planet that makes each of them pull the other, Newton did not know; nobody knows to this day; and all we are now able to assert positively is that the known motion of the planet is precisely what would be produced if it were fastened to the sun by an elastic string, having a certain law of elasticity. Now observe the nature of this discovery, the greatest in its consequences that has ever yet been made in physical science:—

I. It begins with an hypothesis, by supposing that there is an analogy between the motion of a planet and the motion of a ball at the end of a string.

II. Science becomes independent of the hypothesis, for we merely use it to investigate the properties of the motion, and do not trouble ourselves further about the cause of it.
William Kingdon Clifford
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