This animated video of light pulses from Earth make it clear how far away Mars is
by Mark Frauenfelder from on (#53NN5)
*UPDATED* Earth to the Moon, then Mars, at the speed of light (equidistant pulses version) [OC] from r/dataisbeautiful
From the Data is Beautiful subreddit, a visualization of how long it takes for light to travel from Earth to the Moon, and then from Earth to Mars.