Cosmicly

Cosmicly is a Python package that answers the important questions in life:

• How much would I weigh on Jupiter?
• How old would I be on Mercury?
• What time is it on Mars right now?
• How long would it take to drive to Neptune?

It uses real orbital periods, gravity, and solar day lengths for the eight planets and Earth's Moon, so the numbers are (mostly) real, even if the questions are strange.

Install

pip install cosmicly

cosmicly on PyPI · Requires Python 3.11 or newer.

Install from source (for contributors)

You need Python 3.11 or newer and Pipenv. Run these commands in a terminal:

git clone https://github.com/software-students-fall2026/python-package-exercise-LCDJ.git
cd python-package-exercise-LCDJ
pipenv install --dev
pipenv run python -m pip install -e .

The editable install lets Python import cosmicly from src and pick up your changes immediately. The package includes its planetary data and needs no environment variables or database.

Use cosmicly

Save these examples in a Python file and run it with python your_script.py (or pipenv run python your_script.py if you installed from source). For an interactive tour of the package, run the included example program:

pipenv run python example.py

Age and weight

age_on_planet converts Earth years to years on the destination using its orbital period. earth_age calculates your age in Earth years from a birthdate. weight_on_planet scales an Earth weight in "w" mode and calculates weight in newtons from a mass in kilograms in "m" mode.

from cosmicly import age_on_planet, earth_age
from cosmicly.planetary_weight import weight_on_planet

print(age_on_planet(20, "mercury"))            # 83.0 Mercury years
print(earth_age("2000-01-01"))                 # Age in Earth years as of today
print(weight_on_planet("w", 70, "mars"))       # 26.43 in the input weight unit
print(weight_on_planet("m", 70, "moon"))       # 112.0 newtons

Planetary clocks and comparisons

relative_time returns an HH:MM:SS reading on a simulated planetary clock. It starts the Earth and destination clocks together at midnight and uses the destination's solar day length. Pass a datetime for a fixed reference reading or omit it to use the current local time. compare_planets returns your age and weight on two different destinations as a dictionary.

from datetime import datetime

from cosmicly import compare_planets, relative_time

print(relative_time("mars"))                             # Simulated time now
print(relative_time("mars", datetime(2026, 1, 1, 12)))     # 11:40:44

comparison = compare_planets("mars", "jupiter", "2000-01-01", 70)
print(comparison["mars"]["age"])
print(comparison["jupiter"]["weight"])

Travel from Earth

distance_from_earth gives the distance to a planet in km. Without a date it uses the closest approach; with a date ("YYYY-MM-DD" or a date) it uses the real distance on that day, since planets move. travel_at_speed gives the travel time at any speed in km/h, and drive_to, fly_to, and light_speed_to use car, plane, and light speed. arrival_age tells you how old you'll be when you arrive. format_duration turns seconds into readable text.

from cosmicly.planetary_travel import (
    arrival_age,
    distance_from_earth,
    drive_to,
    fly_to,
    format_duration,
    light_speed_to,
    travel_at_speed,
)

print(distance_from_earth("moon"))             # 384400 km
print(travel_at_speed("mars", 40_000))         # Travel time at 40,000 km/h
print(drive_to("mars"))                        # 89 years at 100 km/h
print(drive_to("mars", "2026-11-10"))          # 232 years, real distance that day
print(fly_to("moon"))                          # 18 days at 900 km/h
print(light_speed_to("mars"))                  # 4 minutes
print(arrival_age("mars", 100, 20))            # 109.44, your age when you arrive
print(format_duration(3600))                   # 1 hour

Build and test

Run these commands from the repository root after installing the development dependencies:

pipenv run python -m build
pipenv run python -m pytest
pipenv run python -m pytest --cov=cosmicly --cov-report=term-missing

The build writes a wheel and a source archive to dist/. The tests live in tests/. GitHub Actions builds the package and runs the tests on pull requests targeting main. Tests workflow

Team

• Carina Ilie
• Abubakar Diallo
• Julian Leitersdorf
• Leonid (Leo) Gurevich

Data sources

The package stores orbital periods, gravity, distances from the Sun, and solar day lengths in data.py. NASA Planetary Fact Sheet · NASA Mars24