Mike Jones, age 12, of Ramona, Calif., for his question:

How much would a boy weigh on Jupiter?

Astronauts are in training, Space experts are designing ships, machines and instruments. The problems are enormous, but soon mankind will visit other worlds. And most of the work is necessary in order to cope with the force of gravity which hugs us to the face of our home planet.

Your weight is a measure of the pulling power of the earth's gravity. And gravity is a built. in feature of every planet. It is complex because it varies with the mass of a planet and the distance from the planet’s center, No two planets are alike, Each has a different pulling power. Your weight would be different on each planet of the Solar System.

A bag of sugar weighing one pound on earth would weigh 2.64 pounds on the face of giant Jupiter, A boy in a space suit weighs, lets say, 100 pounds on earth. If he lands on Jupiter, he weighs 264 pounds. For every extra pound we weigh on earth, we become 2.614 pounds heavier on the giant of the planets„

This weight is the surface gravity of Jupiter and it applies to every object our young space traveler will find there. His muscles will have to work more than two and one half times harder to move his body. Every object he lifts will be more than two and a half times heavier. Some think that the surface of Jupiter may be a mushy mixture of frozen gases. But even if it is solid enough to stand upon, the pull of gravity would be very hard on the human body.

There is a ratio between a planet’s mass and its gravity   and mass is the amount of matter packed into a certain space or volume. Jupiter is 1,312 times bigger, but it weighs only 317 times more than the earth.  

These are some of the complex factors which give each planet a different pulling power. This pulling power gives weight to every object on the surface of a planet and also extends out beyond the surface of the planet.

It pulls down a falling object at a certain rate of acceleration. The speed up of a falling object is faster on a more massive planet. As a space ship comes nearer the pull of a planet’s gravity gets stronger. In landing and launching, a ship must cope with the 3 tricky aspect of gravity or it will crash. This calls for complex mathematical plotting. Landings and launchings on giant Jupiter will be much harder, nuch more dangerous than on earth.

If we double the distance between, say, a space ship and Jupiter, the pull is reduced to one quarter   for gravity diminishes with distance. At a certain speed, called escape velocity, a ship can cancel out the pull of a planet. At seven miles a second, a ship reaches earth’s escape velocity and can leave its home planet without effort. But the escape veloci4'y on the massive planet Jupiter is 37 miles a second.