An impossibly lovely primer on how gravity works and why we don’t fall to the center of the earth daily.
As a lover of vintage children’s books, especially ones about science and space, I was thrilled to chance upon the 1971 gem Weight and Weightlessness (public library; Abe Books) by science writer and then-director of Hayden Planetarium educational services Franklyn M. Branley — which renders him cultural kin to Neil deGrasse Tyson. Written less than two years after the historic Apollo 8 moon landing and featuring impossibly lovely Gorey-esque illustrations by British-born, Canadian-raised, California-based artist Graham Booth, this out-of-print charmer tackles the scientific puzzle of what weightlessness actually is through examples from both everyday life and the fascinating world of space exploration — a subject at once of enormous cultural importance and suffering tragic political neglect at the moment.
When you weigh yourself, you step on a scale. The gravity of the earth pulls you down onto the scale. Suppose you weigh sixty pounds. That means gravity is pulling you with a force of sixty pounds.
The scale tells how strongly gravity is pulling you down toward the center of earth. If there were a deep hole under the scale, gravity would pull you all the way to the center of the earth.
The scale and the floor beneath you keep you from being pulled to the center of the earth. They push up against gravity as gravity pulls down.
You can feel the pressure on the soles of your feet. That’s what a scale really measures. It tells how much push upward there is against the pull of gravity downward.
Suppose, all of a sudden, there was a deep hole under the scale. And suppose you and the scale fell into the hole. You would not feel any push upward on the soles of your feet. There would be nothing pushing upward against the downward pull of gravity. Now the scale would read zero.
As long as you keep falling you would be weightless.
That’s why astronauts in spaceships are weightless. They are falling. Nothing is pushing back against them. They are falling around the earth. The astronauts are falling, the spaceship is falling, and so is everything inside it.
They do not look as if they are falling. But they are.
If the rocket went up straight and then changed direction, gravity would still pull it back to the earth. But now the rocket would not come straight down. It would move in a curved path.
Astronauts like weightlessness for a while. It’s fun to float in space. And it’s funny to see things floating around you.
But after a while, an astronaut gets tired of being weightless. He likes to feel something solid under his feet when he stands up. And he likes to feel a bed under his back when he lies down. Also, it’s nice to have food served on a plate, instead of squeezing it out of a tube.
Weight and Weightlessness is well worth the hunt for a surviving used copy. Complement it with Isaac Asimov on the value of space programs, an illustrated chronicle of the Space Race, and Neil deGrasse Tyson’s moving Senate testimony on the spirit of space exploration.