What this calculator does
Synodic Period works out time between successive alignments of a body with Earth, or another chosen reference body. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Sidereal period of the body (Psid) (days) | A number, measured in days. Starts at 687. |
| Reference body sidereal period (P0) (days) | A number, measured in days. Starts at 365.25. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with sidereal period of the body (psid)
Every other input is held at the calculator’s starting values while sidereal period of the body (psid) varies. Select any row to load that scenario into the calculator.
| Sidereal period of the body (Psid) (days) | Synodic period (Psyn) | Synodic period | Sidereal period used |
|---|---|---|---|
| 344 | 5,912.75 days | 16.188 years | 344.00 days |
| 515 | 1,256.12 days | 3.439 years | 515.00 days |
| 687 | 779.88 days | 2.135 years | 687.00 days |
| 1,031 | 565.64 days | 1.549 years | 1,031.00 days |
| 1,374 | 497.50 days | 1.362 years | 1,374.00 days |
| 2,061 | 443.92 days | 1.215 years | 2,061.00 days |