How Far Away Are the Stars? — Parallax Game

Overview

"How far away are the stars?" is one of the oldest questions in astronomy — and the answer involves a surprisingly simple geometric trick: parallax. This educational game, developed by Jan-Niklas Hissel at the University of Cologne as part of his master's thesis, guides students through the concept via animation, interactive exercises, and a final challenge in which they calculate the distance to an uncharted star. The narrative follows a mother and daughter exploring the night sky together, providing a coherent learning arc from motivation to measurement.

Grades	7–10
Subject	Physics, Natural Sciences, Mathematics
Method	Interactive educational game
Duration	Variable (full session ~45 min)
Language	German, English (voiceover in both)
Platform	Android, Windows (32- and 64-bit)

What is Parallax?

Parallax is the apparent shift in the position of a nearby object against a distant background when the observer changes position. A familiar example: hold a finger in front of your face and close each eye alternately — the finger jumps relative to the background. The closer the finger, the larger the jump.

In astronomy, Earth's orbit around the Sun provides the baseline. As Earth moves from one side of its orbit to the other (~300 million km apart), nearby stars appear to shift against the background of much more distant stars. The amount of shift — the parallax angle — is inversely proportional to the star's distance. This method is the first rung of the cosmic distance ladder and was measured with milliarcsecond precision by the Hipparcos satellite and now at microarcsecond precision by ESA's Gaia mission.

Structure of the Game

1. Introduction — A short animation frames the problem: how do we know how far away the stars are?
2. Tour of the Solar System — An overview of distances within our neighbourhood, building intuition for scale.
3. Parallax at road speed — Students observe parallax during a simulated car journey and formulate a rule.
4. Distance calculation — The geometric relationship between baseline, parallax angle, and distance is explained and practised.
5. Stellar parallax — Students observe simulated star fields from two positions on Earth's orbit.
6. Final challenge — Students measure the parallax of an unknown star, construct the geometric triangle, and calculate its distance.
7. Quiz — A short knowledge check at the end.

Features

• Three difficulty levels — switchable at any time
• Both languages — German and English, fully voiced
• Adjustable volume — separate sliders for music and speech
• Hints on demand — small animations, formulae, and a built-in calculator appear when help is requested
• Shortcut / save system — the game can be paused and resumed later

Downloads

Downloads for Android (.apk) and Windows (32-bit and 64-bit) are available at astro-lab.app. An iOS version exists but has not been fully tested. A student worksheet (.pdf) and a teacher information sheet (.pdf) accompany the game.

All content developed by Jan-Niklas Hissel, University of Cologne.

Classroom Use

The game is designed for individual or paired use on a tablet, laptop, or desktop. The accompanying worksheet can be used for assessment or to structure a post-game discussion. The teacher information sheet summarises the physics and provides discussion prompts.

Connection to Current Research

ESA's Gaia satellite, launched in 2013, has measured parallax distances to more than one billion stars. The mission has fundamentally revised our understanding of the Milky Way's structure, stellar populations, and the local distance scale — all built on the same geometric principle students practise in this game.