Age on Other Planets

from datetime import date

ORBITAL_PERIODS = {
    "Mercury": 0.2408467,
    "Venus": 0.6151972,
    "Earth": 1.0,
    "Mars": 1.8808158,
    "Jupiter": 11.862615,
    "Saturn": 29.447498,
    "Uranus": 84.016846,
    "Neptune": 164.79132,
}

def age_on_planets(birth_date: date, ref_date: date | None = None) -> dict:
    if ref_date is None:
        ref_date = date.today()
    earth_years = (ref_date - birth_date).days / 365.25
    return {
        planet: round(earth_years / period, 2)
        for planet, period in ORBITAL_PERIODS.items()
    }

birth = date(1990, 6, 15)
ages = age_on_planets(birth)
for planet, age in ages.items():
    print(f"{planet:8s}: {age:8.2f} years")