Perihelion occurs in winter and aphelion in summer.
The distances of the planet from the sun at aphelion and at perihelion are nearly in the ratio 6:5.
Now, there will be times when the earth is at its extreme of aphelion or of perihelion, when one hemisphere will be most turned to the sun in its midsummer position and the other most turned away at its midwinter position.
When the summer of one hemisphere happens at perihelion and the winter at aphelion, it will be clear that the summer of the other hemisphere will happen at aphelion and its winter at perihelion.
And as the precession of the equinoxes goes on, a time will come when the summer-winter position will come not at aphelion and perihelion, but at the half-way points between them.
In just one half of that time, or in about six weeks, it passes from aphelion to perihelion; that is to say, in six weeks the whole change in its distance from the sun takes place.
At aphelion Mercury is about two and four tenths times hotter than Venus; then it rushes sunward, and within forty-four days becomes six times hotter than Venus.
In order to meet the objection that the diffusion of the rays in aphelion do not differ sufficiently, the solar pyrometer has been so arranged that the density, i.
The area of a sphere whose radius is equal to the earth's distance from the sun in aphelion being to the sun's area as 218.
Encke has discovered the existence of a comet of so short a period of revolution that it remains entirely within the limits of our planetary system, attaining its aphelion between the orbits of the smaller planets and that of Jupiter.
From the point of view of the importance of finding out the divergence of a cometary orbit from a parabola, its period, and its aphelion distance, this increase of range attains the very highest value.
At present, the aphelion occurs at the time of our northern summer; and the perihelion during the summer of the southern hemisphere.
Of the thirteen constituting this group, twelve have orbits falling between those of Mars and Jupiter: one only having its aphelion beyond the orbit of Jupiter.
When the earth is in aphelion than when in perihelion.
Consequently the aphelion distance would be somewhat greater than the mean distance of Uranus.
When at aphelion the planets move slower, and when at perihelion they move quicker than at the mean distance.
An increase in eccentricity would merely shorten the journey, ifaphelion always coincided with opposition, which it would not.
Goldschmidt to revolve in an elliptic orbit, the perihelion of which is exterior to the orbit of Mars, and the aphelion immediately beyond that of Jupiter.
This period nearly corresponds to those of several comets whose aphelion distances are somewhat greater than the mean distance of Jupiter.
Its orbit is the least eccentric of all known comets: the perihelion being exterior to the orbit of Mars; the aphelion interior to that of Jupiter.
We have seen that the comet of 1866, and also the meteoroids following in its path, have their perihelion at the orbit of the earth, and their aphelion at the orbit of Uranus.
With a period of 27 years, the perihelion being interior to the earth's orbit, the aphelion distance of the meteors would be very nearly equal to the distance of Uranus.
Mars is then passing perihelion, while our world is at aphelion (or greatest distance from the Sun).
They ventured into the void beyond Pluto's aphelionfor hundreds of millions of kilometers -- although not yet the stars.
Colonizing Pluto and constructing space kits that would be transformed into surface habitat and supply depots began centuries earlier when Planet Pluto was barely past aphelion but within economical range of deep space transports.
At aphelion it recedes to thirty-five times the distance of the Earth, far beyond the orbit of Neptune.
In the six weeks in which Mercury moves from aphelion to perihelion, it approaches the Sun by fourteen millions of miles, and the heat received by it is increased 2-1/2 times.
But at aphelion it retreats deep into the region of the asteroids, and is much more than four times the mean distance of the Earth.
When the earth is nearest the sun she is in her perihelion; and in her aphelion at the farthest point.
At aphelion he receives four times as much heat and light as the earth.
Its distance, too, is at all times so great that there would be no appreciable change in temperature between its perihelion and aphelion positions.
If the radial disturbing force be exterior to the disturbed body, it will diminish the central force, and cause a progressive motion in the aphelion point of the orbit.
At the aphelion the comet lingers through half his period, giving ample time for the nucleus to be permeated by ether proportionally dense with the surrounding ether of the vortex at that distance.
At the perihelion the planet is urged from the sun and at the aphelion towards the sun.
But why (we may ask) should not this also be expended on the motion of the aphelion as well as in the case of the moon?
But the eye of science sees it as having passed its aphelion beyond the orbit of Neptune in 1873, and is already hastening back to the warmth and light of the sun.
APSIS, plural apsides, the line joining the aphelion and perihelion points; or the major axis of elliptical orbits.
