The Invisible Shield Forty Miles Above Your Bed

Every night, while you sleep, the Earth faces an onslaught you never see. Thousands of meteoroids — some no bigger than a grain of sand, others the size of a fist — streak toward the planet at speeds exceeding 40,000 miles per hour. Any one of them could punch through a rooftop like a bullet through paper.

But they never reach you.

Forty miles above your pillow, the mesosphere stands guard. This layer of atmosphere superheats each incoming rock to over 3,000 degrees Fahrenheit, burning it to vapor in a fraction of a second. What you occasionally glimpse as a shooting star is actually evidence of your protection at work. Scientists at NASA's Meteoroid Environment Office in Huntsville, Alabama, estimate that roughly 48 tons of material strikes the atmosphere daily. Almost none of it survives the descent.

You set your alarm. You pull up the covers. You close your eyes without a single thought about the barrage overhead. The shield never flickers, never fails, never takes a night off.

The psalmist understood this kind of tireless guardianship long before anyone mapped the upper atmosphere. "He who watches over you will not slumber," he wrote. "The Lord will keep you from all harm — he will watch over your life, your coming and going, both now and forevermore."

You have always been more protected than you knew. The God who keeps you makes the mesosphere look like a screen door.