Perihelion Distance
The distance between the orbiting body and the sun at it's closest approach.
Perihelion distance: 0.587 AU
Orbital eccentricity: 0.967
Orbital inclination: 162.24°
Orbital period: 76.0 years
Next perihelion: 2061
Diameter: 16 x 8 x 8 km ...
Perihelion distance
p
These orbital elements tell us the orientation of an orbit: ...
0 au, and perihelion distances qSee also: Asteroid, Aten asteroids, Perihelion distance, Semimajor axis Asteroid One of a number of objects ranging in size from sub-km to about 1000 km, most of which lie between the orbits of Mars and Jupiter; ...
Members of this group have perihelion distances that are greater than 1.017 AU, which is Earth’s aphelion distance, but no greater than 1.3 AU. Amor asteroids therefore do not at present cross Earth’s orbit.
Mean distance from Sun 149,598,500 km (8.3 lt-min): perihelion distance (early January) 147,100,000 km; aphelion distance 152,100,000 km; vorb 29.78 km s-1; orbital period 365d.2564; e = 0.0167, i = 0; obliquity (1973) 23°26'34". Albedo 0.
Using Kepler's laws of planetary motion (see Section 2.4), calculate the orbital period of a comet with a perihelion distance of 0.5 A.U. and aphelion in the Oort cloud, at a distance of 50,000 A.U. from the Sun.
Elements defining the shape of an orbit are the semi-major axis (a), orbital eccentricity (e) and perihelion distance (p).
Apollo asteroids have semimajor axes (a) that are greater than or equal to 1 AU and perihelion distances that are less than or equal to 1.0 AU; thus, they cross the Earth's orbit when near the perihelia of their orbits.
In terms of orbital elements, NEOs are asteroids and comets with perihelion distance q less than 1.3 AU. Near-Earth Comets (NECs) are further restricted to include only short-period comets (i.e., orbital period P less than 200 years).
These objects could have had their orbits and perihelion distances "lifted" by the passage of a nearby star when the Sun was still embedded in its birth star cluster.[4] ...
Near-Earth objects (NEOs) are asteroids, comets and large meteoroids whose orbits bring them close (perihelion distance AU) to Earth's orbit , and which may therefore pose a collision danger.
The orbit is usually highly elliptical or even parabolic (average perihelion distance less than 1 AU; average aphelion distance, roughly 104 AU).
Some Apollo objects can approach closer than Mercury to the Sun, the record-holder being 1995CR with a perihelion distance of 0.12 AU.
96P/Machholz 1 has the smallest perihelion distance of any known periodic comet. It passes so closely that the SOHO spacecraft imaged it as it went around the Sun in October 1996.
Atens: semimajor axes less than 1.0 AU and aphelion distances greater than 0.983 AU;
Apollos: semimajor axes greater than 1.0 AU and perihelion distances less than 1.017 AU
Amors: perihelion distances between 1.017 and 1.3 AU; ...
They have semimajor axes greater than 1 astronomical unit (AU), and perihelion distances less than 1.017 AU. Geographos is an Apollo.
He discovered Comet C/1961 R1 (Humason), notable for its large perihelion distance.
Apollo asteroids have an orbit that crosses the orbit of the Earth and have a period longer than 1 year. They have a semimajor axes greater than 1 astronomical unit (au), and perihelion distances less than 1.017 au.
Near-Earth Object (NEO) A comet or asteroid whose orbit brings it close to Earth's orbit. The criterion is a perihelion distance < 1.3 AU.
(2) Classical KBOs are the majority of the KBOs and have small eccentricities in their orbits and maintain large separations from Neptune. (2) Scattered KBOs "possess large, eccentric, inclined orbits that have perihelion distances near q = 35 AU" ...
NEAs are subdivided into the Aten, Apollo, and Amor groups (that are categorized by their perihelion distance (q), aphelion distance (Q), and their semi-major axes (a) of orbit) and the Potentially Hazardous Asteriods (PHAs).
The six orbital elements used for comets are usually the following: time of perihelion passage (T) [sometimes taken instead as an angular measure called "mean anomaly", M]; perihelion distance (q), usually given in AU; eccentricity (e) of the orbit; ...
 See also: Perihelion, Distance, Orbit, Earth, Planet
  
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