2D Solar System Simulation

A small Python modular project to simulate a 2D solar system using Newtonian gravity.

This is a study project for the master 2 course ScientificSoftware at ENS de Lyon.

Author: Leo Boux de Casson Project start date: September 2025

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Features

• Modular functions for gravitational force, acceleration, position, and velocity updates.
• N-body simulation in 2D.
• Configurable number of planets (Sun + N planets).
• Choice of numerical integrator: Euler or RK4.
• Plotting of 2D trajectories (orbits).
• Optional coordinate timeseries for each planet.
• Optional center-of-gravity (CoG) plotting.
• Unit tests using pytest.

Usage

Run the simulation from the command line:

python main.py --nplanets 4 --steps 10000 --dt 80000 --method rk4 --outfile orbits.png --timeseries timeseries.png --show

Arguments:

Option	Description	Default
--nplanets	Number of planets to simulate (including the Sun)	2
--steps	Number of time steps	365
--dt	Time step in seconds	86400 (1 day)
--method	Integration method: rk4 or euler	rk4
--outfile	Filename for orbit plot	orbits.png
--timeseries	Filename for coordinate timeseries plot	timeseries.png
--show	Show plots interactively	False
--cog	Include center-of-gravity subplot in timeseries	False

Project Structure

.
├── solar_system
│ ├── cli.py
│ ├── dynamics.py
│ ├── integration.py
│ ├── planets.py
│ ├── plot_utils.py
│ └── run_simulation.py
├── tests
│ ├── conftest.py
│ └── test_all.py
├── LICENSE
├── main.py
├── README.md
├── orbits.png
└── timeseries.png

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Installation

1. Clone the repository:

git clone cd Solar_System_2D_test

2. (Optional) Create a virtual environment and install dependencies:

python -m venv venv source venv/bin/activate # Linux/macOS venv\Scripts\activate # Windows pip install numpy matplotlib pytest

Running Tests

Run all unit tests with:

pytest -v

All key functions in dynamics, integration, and planets are tested.

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Contact

For questions or feedback, email me at leo.bouxdecasson@example.com.

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change. Please make sure to update tests as appropriate.

License

This project is licensed under the GNU License.