The article Try it and see by Mark Dominus (The Universe of Discourse) discusses the graphic below, which is part of the “Cosmic Call”, a message to extraterrestrials.

Cosmic Call

The author says that he told his 11-year-old niece,

““I bet you could figure it out if you tried.” She didn’t believe me and she didn’t want to try. It seemed insurmountable.”

I sent this to a few people in my family.

Hint #1

After a little while, I provided some context. The Cosmic Call is:

“In 1999, two Canadian astrophysicists, Stéphane Dumas and Yvan Dutil,... [More]”