re: Halley's Comet begins its return journey to Earth today

quote:

---

Halley encouraged and helped fund the publication of Isaac Newton's influential Philosophiæ Naturalis Principia Mathematica (1687). From observations Halley made in September 1682, he used Newton's law of universal gravitation to compute the periodicity of Halley's Comet in his 1705 Synopsis of the Astronomy of Comets.

---

quote:

---

Edmond Halley did not discover this particular comet, which is racing in for its once-in-a-lifetime visit to the inner solar system. He did something more important. He determined that comets do not travel straight lines or parabolic orbits, passing through once never to be seen again; their orbits are elliptical, a sort of squashed circle. Many comets thus make periodic visits, he concluded, and by plotting with care the characteristics of their elliptical orbits, which he did with ''his'' comet, it was possible to predict their many returns. On Christmas night in 1758, almost 17 years after Halley's death, the comet was seen again as he had predicted. And still faithful to his calculations, the comet that last appeared in 1910 is back again this year, now 105 million miles away and traveling 66,000 miles an hour.

---

quote:

---

Encouragement of Newton

Yet they became colleagues. It was Halley who encouraged the retiring Newton to write down the principles of gravitation he had developed after years of thought supposedly inspired by the legendary falling apple. Newton recognized that gravity on Earth represented the same law of force as that affecting the motion of planets around the Sun. Halley edited the manuscript and arranged financing for publication in 1687 of Newton's great book, ''The Mathematical Principles of Natural Philosophy.'' Halley's encouragement of Newton was perhaps his greatest contribution to science, according to Alan Cook, a professor of natural philosophy at Cambridge University in England. But in applying Newton's laws of gravitation in making his comet prediction, Halley went an important step further. His correct prediction turned out to be the first direct confirmation of Newton's theories.

---

quote:

---

Mark Twain was born on November 30, 1835—two weeks after the perihelion of Halley’s Comet. “I came in with Halley’s Comet,” Mark Twain commented in 1909. “It is coming again next year. The Almighty has said, no doubt, ‘Now there are these two unaccountable freaks; they came in together, they must go out together.’” He died on April 21, 1910—one day after the comet had once again reached its perihelion.

---

quote:

---

I’m keeping a Member’s Only jacket in my chryo-chamber to go with my Guess jeans and Sperry topsiders. No socks of course.

---