# Calculating the Longest Orbital Period

Although we have a working template file, we don't know what we should set the limit to so that all planets can complete their orbits. We can use [`axana`](https://jewels86.gitbook.io/axinite/axana) to find the longest amount of time a body will take to finish it's orbit.

Let's write a quick script to analyze the orbital periods:

```python
import axinite as ax
import axinite.tools as axtools
import axinite.analysis as axana

args = axtools.read("examples/solar-system/my-solar-system.tmpl.ax")
bodies = axtools.load(args, verbose=True)

longest = 0

for body in bodies[1:]:
    orbit = axana.Orbit(bodies[0], body)
    print(f"{body.name}: {orbit.orbital_period}")
    if orbit.orbital_period > longest:
        longest = orbit.orbital_period

print(f"The longest orbital period is {longest} seconds, or:")
print(f"{ax.time_to(longest, "min", round_digits=2)},")
print(f"{ax.time_to(longest, "hr", round_digits=2)},")
print(f"{ax.time_to(longest, "d", round_digits=2)},")
print(f"{ax.time_to(longest, "yr", round_digits=2)}")
```

This script will return multiple values in the console. Take the one that seems most appropriate (for examples, with the template provided eariler, `1.0yr` or `366.11d`) and replace the old limit with it.

```json
{
    "name": "my-solar-system",
    "limit": "1yr",
    "delta": "1hr",
    ...
}
```