Why are solar eclipses so rare?

Category: Best visualization (small and large newsrooms)

Country/area: Japan

Organisation: The Chunichi Shimbun

Organisation size: Big

Publication date: 11 Jul 2019

Credit: Isao Matsunami

Project description:

A visual explanation of the mechanism of two solar eclipses on 26 Dec. 2019 and 21 Jun. 2020. 

Impact reached:

The story reached an above-average level of engagement on social media.

Techniques/technologies used:

Positions of celestial bodies are partly calculated by solving Kepler’s law on the fly, partly obtained from NASA JPL’s HORIZONS database. They are drawn by using webGL and the shadow on the Earth is calculated in the shader program. The interactive feature makes full use of the magnetometer in the mobile device to simulate the eclipse in the reader’s environment. 

What was the hardest part of this project?

Data about celestial events, if drawn to scale, can easily break the boundary of single-precision floating-point number on which webGL works. To make smooth transition of viewpoint along the story, the origin of coordinates is altered seamlessly inside the javascript program.

What can others learn from this project?

Sometimes we have to reconcile ourselves to using deformed charts to explain the subjects in which the very “scale” matters as it is impossible to draw to scale on print media. Dynamic graphics make it easy to explain not only scientific subjects but also environmental issues or economic phenomena in which small number for each reader should be translated to large number for the whole.

Project links: