The longitude of the solar perigee is now 101°, that of the earth's perihelion 281°.
In 1898 the remarkable minor planet Eros was discovered, which, on those rare occasions when in opposition near perihelion, would approach the earth to a distance of 0 .
But the most striking incident in the history of the verification of Newton's law was the return of Halley's comet to perihelion, on the 12th of March 1759, in approximate accordance with Clairault's calculation of the delays due to the action of Jupiter and Saturn.
Cassini, the great comet of 1680 after its perihelion passage; and having returned to England, he married in 1682 Mary, daughter of Mr Tooke, auditor of the exchequer, with whom he lived harmoniously for fifty-five years.
Now such a constellation as the following must sometimes exist: the earth is in perihelion; the line of nodes coincides with the line of apsides and both lie in the line joining earth and sun.
On the other hand the enigmatical motion of the perihelion of Mercury has not yet found any plausible explanation except on the hypothesis that the gravitation of the sun diminishes at a rate slightly greater than that of the inverse square - the most simple modification being to suppose that instead of the exponent of the distance being exactly - 2, it is - 2.000 000 161 2.
It returned to its perihelion in 1835, and was well observed in almost every observatory.
The sun's perigee and the earth's perihelion are so related that they differ 180° in longitude, the first being on the line from the earth toward the sun, and the second from the sun toward the earth.
The usual bands were, however, temporarily effaced in the two brilliant apparitions of 1882 by vivid rays of sodium and iron, emitted during the excitement of perihelion-passage.
Seeliger, published in 1906, who showed that the observed excess of motion of the perihelion of Mercury may be accounted for by the action of that portion of the matter reflecting the zodiacal light which lies nearest to the sun.
An Anomalistic year is the time (365 days, 6 hours, 13 minutes, 48 seconds) in which the earth (and similarly for any other planet) passes from perihelion to perihelion, or from any given value of the anomaly to the same again.
After a rough estimate of the perturbations it must sustain from the attraction of the planets, he predicted its return for 1757,-a bold prediction at that time, but justified by the event, for the comet again made its appearance as was expected, though it did not pass through its perihelion till the month of March 1759, the attraction of Jupiter and Saturn having caused, as was computed by Clairault previously to its return, a retardation of 618 days.
Newcomb found an excess of motions in the perihelion of Mars amounting to about 5" per century.