perihelion

noun

1. The point in the elliptical orbit of a comet, planet, etc., where it is nearest to the Sun.

   “The æquation of the Earth encreaſeth from her Aphelion, until ſhe come to the point where it's greateſt, and from thence it again decreaſeth till ſhe come to her Perihelion, or oppoſite Auge: in like manner it increaſeth from her Perihelion to the point where it's greateſt, and afterwards decreaſeth till ſhe come againe to the Auge or Aphelion, [...]”

   “They [the best astronomers of this age] all agree that the Planets turn in ſo many Ellipſes, of which the Sun is the focus; the reaſon of it is, that they are obſerved to be in ſome points called Perihelia, nearer to the Sun, and, in the oppoſite points call'd Aphelia, farther from it; which could not be, if they mov'd in a perfect circle.”

   “[I]f Comets were obſerv'd to have to Atmoſphere after their return from the Regions beyond Saturn, before they arrived at their Perihelia again, then indeed this reaſoning were unavoidable; but ſeeing the contrary is evident from Aſtronomical Obſervations, it cannot affect his [William Whiston's] Hypotheſis.”

   “This rotational motion could have the axis of minimum moments of inertia nearly aligned with the Sun–Mercury radius vector at every perihelion passage.”

2. (figuratively)The highest point or state; the peak, zenith.

   “[T]he magnificence of his compliment had quite shaken the general's [Ulysses S. Grant's] modesty, and that he could only say that France must come to the perihelion of her glory under such rulers as Grevy [i.e., Jules Grévy].”

   “This brilliant trick was the invention of the late Dr. Hofzinzer, of Vienna, who, at the perihelion of his fame, was regarded as the greatest card conjurer in the world.”

   “At that concert, undergoing a state of rapture that easily rekindles in memory, the boy turned to his best friend Joel and gave the simplest and most unguarded expression possible to a feeling nearly anyone has had at least once (I hope), perhaps most often at the perihelion of some sexual experience, or drug experience. I don't remember the exact words the boy used, but the gist was, "We must never, ever, miss a chance to do this again."”