Contacts
During a transit there are four "contacts", when the circumference of the small circle (small body disk) touches the circumference of the large circle (large body disk) at a single point. Historically, measuring the precise time of each point of contact was one of the most accurate ways to determine the positions of astronomical bodies. The contacts happen in the following order:
- First contact: the smaller body is entirely outside the larger body, moving inward ("exterior ingress")
- Second contact: the smaller body is entirely inside the larger body, moving further inward ("interior ingress")
- Third contact: the smaller body is entirely inside the larger body, moving outward ("interior egress")
- Fourth contact: the smaller body is entirely outside the larger body, moving outward ("exterior egress")
A fifth named point is that of greatest transit, when the apparent centers of the two bodies are nearest to each other, halfway through the transit.
Read more about this topic: Astronomical Transit
Famous quotes containing the word contacts:
“Living more lives than one, knowing people of all classes, all shades of opinion, monarchists, republicans, socialists, anarchists, has had a salutary effect on my mind. If every year of my life, every month of the year, I had lived with reformers and crusaders I should be, by this time, a fanatic. As it is I have had such varied things to do, I have had so many different contacts that I am not even very much of a crank.”
—Rheta Childe Dorr (1866–1948)
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—Marshall McLuhan (1911–1980)
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—Eleanor Roosevelt (1884–1962)