# InterImm Mars Clock

> Time on Mars from Earth time: Mars Sol Date, Coordinated Mars Time (MTC), local solar time at any longitude, season (Ls), Mars Year, rover sols, and the InterImm Mars calendar, clock and 25 timezones. Computed with NASA GISS's Mars24 algorithm. Free, no API key, static files with open CORS.

How to get Mars time, best option first:

1. If you can use MCP tools: add the server `npx -y github:InterImm/mars-clock#gh-pages` (stdio). Tools: `get_mars_time` (now or any instant, any longitude), `interimm_to_earth`, `mission_sol`, `sol_to_earth`, `mars_year_dates`.
2. If you can run a shell with Node 18+: `npx -y github:InterImm/mars-clock#gh-pages now --longitude 137.44` prints JSON.
3. If you can run JavaScript: `import { marsTime, interimmTime } from 'https://cdn.jsdelivr.net/gh/InterImm/mars-clock@gh-pages/lib/marstime.js'`.
4. If you can only fetch URLs: read the precomputed daily table for the year and interpolate (MSD grows by 0.973244 sol per Earth day; MTC by 24 Mars hours per sol). Or compute it yourself from the formulas in llms-full.txt.

Conventions: longitudes are degrees EAST of Airy-0 (west longitudes are negative or 360 minus). MTC, LMST and LTST are in Mars hours (1/24 sol). The InterImm clock uses Earth-length hours, so a sol reads 00:00:00 to 23:59:59 then +00:00 to +39:35. InterImm dates are written year-MM-DD with two-digit month and day (31-01-03); Year 1 began 1970-04-28. Mars Years use Clancy numbering (MY 1 began 1955-04-11; MY 39 began 2026-09-30).

## Docs

- [llms-full.txt](https://interimm.org/mars-clock/llms-full.txt): every function, field and formula in one file
- [README](https://github.com/InterImm/mars-clock#readme): library and API reference
- [Mars Clock page](https://interimm.org/mars-clock/en/): live clock, converter, calendar, timezones

## API

- [OpenAPI description](https://interimm.org/mars-clock/api/v1/openapi.json)
- [Index](https://interimm.org/mars-clock/api/v1/index.json)
- [Daily table, e.g. 2026](https://interimm.org/mars-clock/api/v1/daily/2026.json): 00:00 UTC each day, 2000-2050
- [Mars Year start dates](https://interimm.org/mars-clock/api/v1/mars-years.json)
- [InterImm calendar years](https://interimm.org/mars-clock/api/v1/interimm-years.json)
- [Missions](https://interimm.org/mars-clock/api/v1/missions.json)

## Code

- [marstime.js](https://cdn.jsdelivr.net/gh/InterImm/mars-clock@gh-pages/lib/marstime.js): the library, one ES module, no dependencies
- [MCP server](https://github.com/InterImm/mars-clock/blob/gh-pages/mcp/server.mjs)

## Optional

- [Embeddable widget](https://interimm.org/mars-clock/en/#embed): `<mars-clock-card>` or an iframe
- [Mars24 algorithm (NASA GISS)](https://www.giss.nasa.gov/tools/mars24/help/algorithm.html)