By Ruth Bloomfield on Sept. 5, 2018 at WSJ.com
He was particularly enthused at the prospect of viewing the passage of the planet Venus across the face of the sun—a phenomenon that occurs less than once in a century—and commissioned an observatory from which to view this rare astrological event.
Astrology is the superstitious belief that the course of human events is determined by the locations of the Sun, the Moon, the planets, and the stars in the sky as observed from the surface of the Earth. Astrologers tell fortunes by means of charts they create using astronomical theories invented by the ancient Greeks and Romans which are geocentric and not based on modern physics. An "astrological event" is a manifestation of superstition.
Astronomers are scientists who observe extraterrestrial bodies like the Sun, the planets, and the Stars and use mathematics and physics to deduce the nature of those bodies, Astronomy has existed since ancient times. In the eight century B.C.E., Babylonian astronomers determined when and where the planets would appear in the sky. In the 17th Century, Newton used observations made with newly invented instruments such as the telescope and new forms of mathematics such as the infinitesimal calculus he invented to explain universal gravitation and calculate the orbits of the Moon and the planets with new understanding and accuracy.
The "passage of the planet Venus across the face of the sun", is known among astronomers as a "transit of Venus". One of Newton's contemporaries, Edmund Halley (the comet guy) proposed that telescopic observations of a transit of Venus could be used to measure the distance between the Earth and the Sun, which would provide a yardstick for measuring the distances and sizes of the Sun and the planets. Haley did that in 1716, but the next transits were not predicted to occur until 1761 and 1769.
Astronomers made careful observations of those astronomical events and determined that the earth lay ~95 million miles from the Sun (the correct figure is ~93 million miles). For the first time, men knew with certainty that the Sun and the planets were very far away, and that they could have no effect on the lives of men. Astrology was shown to be superstitious nonsense.