It was June 12 in the Sangin Valley in southern Afghanistan. U.S. Marines had been fighting the Taliban all day and had suffered heavy casualties, including two killed. Several resupply convoys had been turned back by enemy attack. The Marines were running low on food, water, ammunition and medical supplies.

That’s when the Marines’ V-22 Osprey tiltrotor swooped in, carrying life-saving supplies — and machine gun fire.

What happened over the next five minutes or so highlights the incredible bravery of Marine air crews and the Corps’ growing confidence in the accident-prone, maintenance-intensive...

1996: Carl Sagan dies.

Calling Carl Sagan a scientist is a little like calling the Beatles a rock band. Sagan was certainly a scientist (an astronomer, biologist and astrophysicist, to be precise). But he was also science’s most visible public advocate, a secular humanist, a fervent believer in extraterrestrial life, a teacher, an author, a television host and a political activist.

While accurately fixing the surface temperature of Venus and positing the presence of seas on Jovian and Saturnian moons are among his practical contributions to the field of astronomy, his lasting contribution to...