Interplanetary Time Lab

What this page is

This is a lab-style display of time across the solar system. It’s meant to make the core ideas feel tangible without requiring a physics textbook.

Earth Local Time is your reference clock.

Field guide (labels you see on the clocks)

The two big ideas

Time is not universal. Local solar time differs by planet because of rotation and where the Sun is in that body’s sky.

Clocks don’t tick at exactly the same rate everywhere. The ppb vs Earth site label shows how much faster or slower a body runs relative to your Earth site.

So what? It means every clock is valid in its own context, and the UI shows how they relate.

API usage (snapshot data)

The public API is read-only and returns JSON. Use the GET /api/clock/snapshot endpoint with query string parameters that match the observer settings form.

Example request message:

GET /api/clock/snapshot?lat=39.7392&lon=-104.9903&alt=1609.3&tz=America/Denver&time=2024-04-19T12:30:00&shiftWithObserverLongitude=true HTTP/1.1
Host: your-hostname
Accept: application/json

Example response payload (truncated):

{
  "earthLocalTime": "2024-04-19T12:30:00-06:00",
  "snapshotUtc": "2024-04-19T18:30:00Z",
  "isObserverLongitudeShiftApplied": true,
  "observerLongitudeDeg": -104.9903,
  "bodies": [
    {
      "bodyId": "earth",
      "displayName": "Earth",
      "localSolarTicks": 558000000000,
      "dailyRateOffsetPpb": 0.0,
      "category": "Planet",
      "group": "Inner"
    },
    {
      "bodyId": "mars",
      "displayName": "Mars",
      "localSolarTicks": 1123200000000,
      "dailyRateOffsetPpb": -12.3,
      "category": "Planet",
      "group": "Inner"
    }
  ]
}

Tip: you can omit time to use the server’s current local civil time, and omit location parameters to fall back to the configured default site.

What “Earth Local Time” means

It is your local civil time at the selected Earth site and time zone. Internally, the app converts your local civil time to UTC and then to TT before the PlanetaryClockEngine computes the snapshot.

What “local solar time” means on each body

Think of it as “where the Sun is” on that world. Noon-ish is when the Sun is highest in the sky for that location on the planet or moon.

It can feel unintuitive versus your watch because a planet’s rotation rate and day length can be very different from Earth’s.

Why changing Earth location changes other planets

You’re changing the observer site (latitude, longitude, and Time Zone ID). That affects the reference clock and some geometry assumptions used to align the snapshot with “your” perspective.

• Your Earth time zone changes the label shown for the reference clock.
• Your Earth longitude changes what “local solar time” means for Earth specifically.

What “ppb vs Earth site” is

Ppb means parts per billion. It is a rate difference, showing how much faster or slower a body runs compared to your Earth site per day.

Example: +10 ppb is about +0.00000001 seconds per second, which adds up to roughly 0.864 milliseconds over a day.

This value is relative to your observer site, not an absolute rate. The engine computes body rate minus observer rate.

Why you might see small jumps

The UI renders smoothly, but it refreshes from periodic snapshots. That can introduce tiny jumps when a new snapshot arrives.

There is caching and interpolation under the hood to keep updates fast and consistent while the app stays responsive.

Troubleshooting

Accuracy and current limitations

This engine is deterministic and configuration-driven.

Some models are intentionally simplified right now. For example, the SimpleKeplerianEphemerisProvider uses a circular-orbit approximation and the SimpleBodyRotationModel makes simplified rotation-axis assumptions.

So what? The trends are trustworthy even when the fine details are intentionally compact.

Privacy

If you enter a location, we only use latitude, longitude, and time zone to compute the current snapshot. The data stays in the app and is not shared elsewhere.