Astronomical Simulation Animations

What is this page for?

While putting together our free online courses on astrophysics, we found many situations in which a suitable animation or video could really help explain a concept. Sometimes we could find suitable animations on the web, but often we had to create our own.

Several students in the courses have asked if we could make these videos available for them to use in their own classes and talks. That is the purpose of this web page. All these videos are free for you to use - we release them all under the Creative Commons Attribution licence.:

Creative Commons License
Astronomy Animations by Paul Francis is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at

The videos are hosted on a Youtube channel. If you want a copy on your own hard drive for embedding in powerpoint, there are numerous YouTube downloader web sites which will allow you to download the youtube video in the format of your choice.

Note:, I've included brief descriptions of the astrophysics behind each video below, and in the Youtube notes. But for a full understanding of the astrophysics behind these animations, you should wath them in context in the actual series of courses.

Most of these animations were made using the excellent VPython programming language. I provide some of the source code below in case you wish to produce your own simulations.

The Animations

The Big Bang and Cosmology

The universe is currently expanding, due to the Big Bang. There is a common misconception that this was due to an explosion in empty space. Instead, space is full, but every bit is getting bigger, carrying galaxies away from each other even though there is no central "thing" that went bang. These animations are designed to show an infinite yet expanding universe. Each shows galaxies as coloured balls.

The above simulations show galaxies (coloured balls) moving away from each other purely because space is expanding. But in practice, in addition to the expansion of space, galaxies are attracting each other due to their mutual gravitational attraction. On smaller scales (less than a few mega-parsecs) this mutual attraction usually wins, but on larger scales, the expansion of space winds. The next set of videos shows this.

The VPython computer code used to generate the above simulations.

Black Holes

The VPython computer code used to generate the above simulations.

Solar System Formation

When our solar system was forming, it would have passed through a stage when there were vast numbers of small planets orbiting the Sun. As time went on, these would have collided and merged to form the small number of large planets we see today. The simulations in this section show this process. The planet masses and sizes have been greately increased in these simulations to speed up the whole process.

The VPython computer code used to generate the above simulations (extensively modified version of one of the example programs that comes with vPython)..


Why we can't just see planets around other stars - the light from the background star blinds us to the much fainter light from the planet

We usually detect exoplanets indirectly - the following videos show some of the methods currently used.

VPython code used to make the exoplanet animations. The gravitational lensing programs generate a series of images which you must then combine to make a movie using software like Quicktime.

Pulsars, Quasars and Compact Binaries

Carbon Dioxide Resonance and Global Warming

Global warming/greenhouse effect is due to a particular resonance of Carbon Dioxide molecules. In this series of videos, a molecule (left) is exposed to an alternating electric field (right) at different frequencies, showing the two main resonances.

Dark matter and rotation curves

The dark matter in a galaxy shows up by affecting how fast it rotates at different radii.

Flatness of our solar system

Our solar system is very flat, and the planets are in very circular orbits. This is because they came from the collapse of a primordial accretion disk.

Special Relativity

Some animations of different frames of reference, designed to help explain the Lorentz transform.

Miscellaneous Videos

Last Modified, 19th October 2015

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