About LightDelay
LightDelay is a service that uses orbital elements and ephemerides from a variety of sources to provide accurate distance calculations between a wide range of solar bodies.
Data used by this service is provided by variety of sources, including the following projects and resources:
- The AstroPy team's Solar System Ephemerides, for Earth, the Moon, and the major planets.
- The Minor Planet Center's Orbital Elements and Ephemerides data sets, for asteroids, comets, and minor planets
- Other sources, including points on Earth, Earth satellites, and more, to come whenever I get around to it.
Links in this service are generally pretty easy to parse and build: "https://lightdelay.space/location_1/location_2/effective_date_and_time/". All parameters are optional. Locations can currently be the name of any planet, many moons, or any asteroid or comet with data in the Minor Planet Center database. Dates and times can be as specific as you like, potentially including time zones. See the following examples:
- https://lightdelay.space/: Using no arguments gets you the homepage, with common locations and the current time.
- https://lightdelay.space/Mars/: A single argument is interpreted as the location you want the distance to. The distance is calculated from the center of Earth to that location at the current time. This example uses a major planet.
- https://lightdelay.space/1_Ceres/: You can use underscores in place of spaces to make prettier URLs. This is the distance to Ceres, a major belt asteroid, at the current date and time.
- https://lightdelay.space/Eros/: Even though the formal designation of Eros is "433 Eros", you can use the common name.
- https://lightdelay.space/2018_WX/: This is an example using a preliminary designation of an asteroid, a systematic name assigned when an asteroid is first discovered.
- https://lightdelay.space/2000-01-01/: You can also get the homepage using a preferred timestamp. Defaults to midnight UTC if a time and timezone aren't specified.
- https://lightdelay.space/2000-01-01 12:34 PM UTC-4/: If you include a time and timezone, the time will be converted to UTC.
- https://lightdelay.space/Deimos/: Moons are supported now as well.
- https://lightdelay.space/ISS/: Earth satellites are a planned extension, but not fully supported yet.
- https://lightdelay.space/Io/: Named moons and similarly named asteroids can still be ambiguous; use the numbered designation when needed.
- https://lightdelay.space/Mars/1_Ceres/: Distance between any two objects is supported now.
- https://lightdelay.space/Mars/2000-01-01/: You can also provide one location and a time.
- https://lightdelay.space/Mars/1_Ceres/2000-01-01/: Or use all three arguments: two locations plus a date and time.
There are some important caveats. First, the location histories and predictions of objects are not always 100% accurate. Orbits are actually really quite complicated. Here's what should work:
- Planets: Positions should be accurate between the years 1950 and 2050.
- Minor Planets and moons: Positions should be accurate from when they were first observed until the present day, however, predictions into the future may not be accurate.