eccentricity
(e, orbital eccentricity)
(degree to which an orbit is non-circular)
The term eccentricity is used to an orbit's non-circularity,
and is more specifically used for a numerical quantification (e)
of the non-circularity of an orbit: zero for a circular orbit,
between zero and one for an elliptical orbit, 1 for a parabolic
trajectory, and greater than 1 for hyperbolic.
These types of curves, termed conic sections, trace each
path of a pair of bodies due to gravitational
interactions between them.
The eccentricity of an elliptical orbit (covering virtually all of
what we think of as "orbits") is:
ra - rp
e = ———————
ra + rp
Where:
- e is the eccentricity.
- ra is the orbiting body's orbital radius at apoapsis (i.e., its furthest distance from the pair of bodies' center of mass).
- rp is the orbiting body's orbital radius at periapsis (i.e., its closest distance from the pair of bodies' center of mass).
Earth's orbit has an eccentricity of 0.0167, the Moon's is 0.0549,
and Halley's Comet's is 0.97.
An extra-solar planet's orbital eccentricity can aid in the study of
its atmosphere: electromagnetic radiation from the system includes reflected
light from the planet, which varies with the varying distance between
host star and planet, including effects of the planet's atmospheric
temperature and weather resulting from this varying temperature.
Differential spectroscopy through the course of the orbit offers
additional clues regarding the atmosphere's constituents.
(orbits,celestial mechanics,measure)
Further reading:
https://en.wikipedia.org/wiki/Orbital_eccentricity
https://astronomy.swin.edu.au/cosmos/o/Orbital+Eccentricity
http://hyperphysics.phy-astr.gsu.edu/hbase/kepler.html#c3
https://sciencepickle.com/earth-systems/star-planet-connection/planet-eccentricity/
Referenced by pages:
51 Eridani b
Alpha Centauri (α Centauri)
apsis
binary star
black hole merger
Ceres
comet
Comet Shoemaker-Levy 9
damocloid
DQ Tau
Earth
EXOSAT
exosphere
extreme mass ratio inspiral (EMRI)
giant planet
gravity assist
gravity sounding
Haumea
HD 80606 b
heartbeat star
heliometer
Hill radius
Jupiter
K2-18b
Kirkwood gap
Kozai mechanism (ZLK)
Kuiper Belt (K Belt)
Laplace radius (rL)
late heavy bombardment (LHB)
libration
Mars
Mars crosser (MC)
mean anomaly
Mercury
moon
Neptune
Oort Cloud
orbital element
orbital resonance
orbital speed
Parker Solar Probe (PSP)
planet formation
Planet Nine
Pluto
precession of the equinoxes
PSR B1259-63
Psyche
quasi-satellite
rotation period
Saturn
Sedna
semi-major axis (a)
sidereal
solar circle
solar constant
Solar Orbiter (SolO)
solar system
solar system object (SSO)
solar time
synodic period
tidal heating
tidal migration
tidal Q
trans-Neptune object (TNO)
Uranus
Venus
Wind
XO-3b
Index