Night on M13

2013 – 2014

This illustration shows what a night would look like if Earth was orbiting a star near the center of M13, the Hercules Cluster.

This was something I always tried to describe to people looking at M13 (or other globular clusters) through the telescopes at the Chabot Space and Science Center.

But who knew if my vision was right or wrong? The only way to find out was to do some research and an illustration as close as possible to what we would actually see.



Click to download a very large version of the image

The image is available in high resolution by clicking the thumbnail on the right. You can print it and use it as you like as long as you keep the credits intact and readable.


Planning the Image

M13 is a globular cluster. The model used was provided by Diederik Kruijssen, a known expert in the field, and is the result of a simulated evolution of M13. It contains 1.17 million stars.

Earth was positioned around a star about 20 light years from the center. The location was chosen after various tests at different distances.

Some of the cluster stars were dead or so faint that were not visible at all from the chosen Earth’s position, but still, about 300 thousand stars were plotted in the portion of the sky visible in the image.

One interesting aspect of the exercise was to figure out how much light actually reaches Earth’s surface. The result was surprisingly bright. In fact, there would be no darkness at all.

On our hypothetical Earth, with the cluster center somewhere above the horizon, the light would be about 10% of the Sun light we are accustomed to during a bright day.

Image Components

The foreground is a pretty straightforward 3-layers rendering done with Maxwell on Amazon EC2 instances. Nothing special other than the amount of geometry and textures details that were necessary for such a large image. The full size image is a 36×48 inches poster at 300dpi.

The stars background was created in Processing by reading the cluster evolution data and calculating each star location, brightness, and color based on the chosen Earth position.

It was a multi-step process where I was able to test the visibility and brightness of the stars, set threshold values for the visual magnitude, and tweak colors and appearance based on their final brightness.

At the end, I used Photoshop to combine foreground and background, mountains, and paint clouds and dirt.


Some WIP and Details




  2014 /  Last Updated January 2, 2017 by Roberto Ziche