Doppler Shift Visualiser

A simple Python and web-based tool for visualising Doppler shift in astronomical spectra.

What this project does

This project shows how spectral lines move when an astronomical object has radial motion relative to the observer.

• Positive velocity means the object is moving away: redshift
• Negative velocity means the object is moving towards us: blueshift

Physics background

For small velocities compared with the speed of light, the Doppler shift can be approximated as:

Δλ / λ = v / c

where:

• Δλ is the change in wavelength
• λ is the original wavelength
• v is radial velocity
• c is the speed of light

Why this matters

Doppler shift is central to observational astronomy. It is used to study:

• radial velocity of stars
• exoplanet detection
• binary stars
• galaxy motion
• spectroscopy

Live Demo

Try the interactive tool

Licence and attribution

Code in this repository is released under the MIT Licence.

Images, diagrams, written explanations, and educational content are © 2026 Biswajit Jana unless otherwise stated.

Please credit this repository if you reuse or adapt any visual or explanatory material.

Suggested attribution:

“Doppler Shift Visualiser by Biswajit Jana — https://github.com/Biswajit1999/doppler-shift-visualiser”

Python version

Run:

pip install -r requirements.txt
python main.py