An Operation Smile volunteer reverses an oxygen mask so a child with a cleft condition can blow a bubble for the first time in Guadalajara, Mexico. (Operation Smile Photos)
Photo credit: via Carl Sagan Planetary Society/Wikimedia Commons and John Finkelstein/Pexels – Carl Sagan used a sliced apple to perfectly explain the fourth dimension.
Photo credit: Images courtesy of NASA and Amazon – Carl Sagan published <a href="https://amzn.to/4aPYzLR">"The Demon-Haunted World: Science as a Candle in the Dark"</a> in 1995.
