ephemeral

Parser and visualizer for JPL Ephemeris Files. Trajectories are available to the public via the JPL Horizons System.

Examples

dune exec -- ephemeral test/voyager_2/*.txt --speed=9 --title="Voyager II" --dynamic-scale=true

dune exec -- ephemeral test/cassini/*.txt --title="Cassini" --speed 5

dune exec -- ephemeral test/earth_sun_march2026.txt --title="Earth-Sun March 2026" --speed=9

dune exec -- ephemeral test/rosetta/*.txt --title="Rosetta Probe - Comet 67P" --speed=7

dune exec -- ephemeral test/parker/*.txt --title="Parker Solar Probe" --phi=-1 --theta=3.93

dune exec -- ephemeral test/iss.txt --title "ISS March 1st 2026" --theta=45 --phi -1.25

Installation

From opam:

opam install ephemeral

From source:

git clone https://github.com/CharlesAverill/ephemeral.git && cd ephemeral
opam install . --deps-only
make

Controls

Key	Effect
Escape	Exit
Space	Pause
,	Slow down
.	Speed up
/	Default speed
z	Toggle dynamic scaling

CLI Usage

Usage: ephemeral [OPTION]... [VECTOR_TABLE]...
  --speed    <int>   Sets the starting speed of the simulation
                     (0-9, default=4)
  --dynamic-scale 
             <bool>  Determines whether view scales with scene
                     (default=false)
  --theta    <float> Sets the starting azimuth of the viewport
                     (0-6.28, default=0)
  --phi    <float> Sets the starting elevation of the viewport
                     (-1.570796-1.570796, default=0.000000)
  --record   <path>  Runs one loop of the ephemerides and calls
                     ffmpeg to render a video from the frames
  --title    <str>   Draws text to the top of the screen
  --help  Display this list of options

If passing multiple vector tables, they must share the same central object (e.g., all tables must be heliocentric, or geocentric, or etc.).

Installation

opam install . --deps-only
dune build