For the International Day of Light: calculate how long light takes to reach the places that matter to you — grandma’s house included — and draw what light looks like.
HostOpenTencor (opentencor.ai)
RunsMay 10 – 23, 2027 · Peak day: May 16, the International Day of Light
CostFree. The calculator needs no registration and collects no personal information
PrizesNone, and no rankings. Every participant gets a Speed of Light Certificate.
An unserious week, on purpose
OpenTencor spends its days on a serious subject — the optical interconnects that feed AI data centers. For one week in May, it hands light back to the people it first belonged to: anyone who ever looked up and asked why stars twinkle.
Two ways to play
Calculate. Enter a distance that means something to you — home to school, Earth to the Moon, here to grandma’s house — and see how long light takes to run it. Generate your own printable Speed of Light Certificate. (A “hello” to Mars, you will learn, takes minutes each way.)
Draw. Children can draw what light looks like. A parent or legal guardian submits the drawing for the Gallery of Light.
Protecting young artists — the core terms
Drawings may be submitted only by a parent or legal guardian; submitting means the guardian agrees to public display.
The gallery shows only the child’s first name or nickname and age band — never a school, an exact location, or any contact information.
A guardian may ask for a drawing to be taken down at any time; it is removed immediately.
Submitting grants the organizer a non-exclusive license to show the drawing on this event page and in event reporting. Copyright stays with the young artist. Drawings are never used in advertising or merchandise.
The gallery
There are no places and no winners. Editors hang drawings in batches by how well they fit the theme, under one consistent standard. If submissions exceed the wall space, not every drawing can be hung — but every submission receives a thank-you page.
Launching May 10, 2027
Registration is not open yet. Leave your name and email address and we will send you one email when it opens — nothing else, and no newsletter.
The light turns on May 10, 2027Free · Family friendly · Guardian consent for every drawing
On May 16, the gallery’s first wall goes up together with a small data note: how many distances were calculated, and whether the Moon or grandma’s house won.