| Cometary Orbital Elements | ||
|---|---|---|
| Element name or symbol | Celestia SSC keyword | Description |
| Epoch | Epoch (1,2) | Julian date when elements are valid |
| e or Ecc | Eccentricity | Elongation of ellipse: 0.0 = circle, 1.0 = parabola, .gt. 1.0 = hyperbola (pure number) |
| q | PericenterDistance | Closest approach to Sun (in AU) |
| T or Tp | Epoch (1,2) | Time of PeriCenter passage (Julian date) |
| Node or W or Ω | AscendingNode | Where the Orbit crosses the Ecliptic (longitude, in degrees) |
| Peri or w or ω | ArgOfPericenter | angle from "Node" to Pericenter (in degrees) |
| Incl or i | Inclination | Tilt of orbit from Ecliptic (in degrees) |
| (not provided) | Period | calculated orbital
period (in Earth years), using either
P = (q/(1-e))^1.5 for a closed, elliptical orbit P = (q/(e-1))^1.5 for an open, hyperbolic orbit Unfortunately, P is undefined for a parabolic orbit. |
C/1995 O1 (Hale-Bopp)
Epoch 1997 Mar. 13.0 TT = JDT 2450520.5
T 1997 Apr. 1.1373 TT Nakano
q 0.914142 (2000.0) P Q
z +0.005395 Peri. 130.5887 -0.1331204 -0.1703043
Node 282.4707 +0.2822928 +0.9378055
e 0.995068 Incl. 89.4300 +0.9500472 -0.3025183
From 3000 observations 1993 Apr. 27-2001 Feb. 17, mean residual 0".8.
Nongravitational parameters A1 = +1.27, A2 = +0.1144.
Note that Celestia does not properly handle object names which include
a "/". That character is used by Celestia as a separator between object
names. As a result, a name which contains a "/" cannot be defined to
have a satellite, nor can it be selected by typing a
[carriage-return] followed by the name of the object.
Otherwise such a name is OK: the name can be selected using Celestia's
"Solar System Browser", for example.
#C/1995 01 Hale-Bopp (CfA)
# "name of object" "name of primary"
"Hale-Bopp" "Sol"
{
Class "comet"
Texture "asteroid.jpg"
Mesh "asteroid.cms"
Radius 20.0 # arbitrary
RotationPeriod 11.34 # arbitrary
# taken from
# http://cfa-www.harvard.edu/iau/Ephemerides/Comets/1995O1.html
EllipticalOrbit
{
Period 2523.363 #calculated: (q/(1-e))**1.5
PericenterDistance 0.914142 # q
Eccentricity 0.995068 # e
Inclination 89.4300 # Incl.
AscendingNode 282.4707 # Node
ArgOfPericenter 130.5887 # Peri.
MeanAnomaly 0.0 # position at T
Epoch 2450539.6373 # T
}
InfoURL "http://www.jpl.nasa.gov/comet/"
}
| Asteroidal (Minor Planet) Orbital Elements | ||
|---|---|---|
| Element name or symbol | Celestia SSC keyword | Description |
| a = (q+Q)/2 | SemiMajorAxis | half of the length of the long axis of an ellipse |
| Epoch | Epoch | Date when elements are valid |
| e or Ecc | Eccentricity | Elongation of ellipse: 0.0 = circle, 1.0 = parabola |
| Node or W or Ω | AscendingNode | Where the Orbit crosses the Ecliptic |
| Peri or w or ω | ArgOfPericenter | angle from "Node" to Pericenter |
| Incl or i | Inclination | Tilt of orbit from Ecliptic |
| M | MeanAnomaly | The location of the body in the orbit at the specified Epoch |
| P = a^1.5 = sqrt(a^3) | Period | time for object to revolve around the Sun |
| q | PericenterDistance | Closest approach to Sun |
| Q (1) | (not used) | apocenter: greatest distance from the Sun |
Orbital elements: 1998 FL5 Epoch 1998 Mar. 8.0 TT = JDT 2450880.5 Williams M 22.37287 (2000.0) P Q n 0.51950119 Peri. 297.40999 -0.54744251 -0.83644649 a 1.5325395 Node 185.97874 +0.82823536 -0.53714947 e 0.3601172 Incl. 14.32281 +0.11971998 -0.10875532 P 1.90 H 21.0 G 0.15
"1998 FL5" "Sol"
{
Class "asteroid"
Texture "asteroid.jpg"
Mesh "asteroid.cms"
Radius 270.0 # table lookup using H
EllipticalOrbit
{
Period 1.90 # P
SemiMajorAxis 1.5325395 # a
Eccentricity 0.3601172 # e
Inclination 14.32281 # Incl.
AscendingNode 185.97874 # Node
ArgOfPericenter 297.40999 # Peri.
MeanAnomaly 22.37287 # M
Epoch 2450880.5 # Epoch
}
InfoURL "http://cfa-www.harvard.edu/mpec/J98/J98F20.html"
}
If you don't tell me that something's missing, unclear or wrong, I can't improve it.