Video shows how long it would take for a bullet to fall on different planets

Astronaut Alan Shepard hit his golf ball 36 meters (118 feet) on the surface of the moon, and scientists at the International Space Station have even started playing baseball in orbit, although if you’re going to be playing sports in space, then you should really familiarize yourself with the behavior of balls through the solar system. To help us, planetologist Dr James O’Donoghue created an animation demonstrating how long it takes for a ball to free fall from a height of one kilometer (0.6 mile) on a selection of celestial bodies.

To create the video, O’Donoghue and his fellow astronomer Rami Mandow referenced data released by NASA regarding the force of gravity at the equator of each planet in the solar system. This allowed them to calculate the time it would take for an object to fall to the surface of each of these worlds, assuming the absence of any wind resistance.

For example, the force of gravity on Earth causes objects to fall at a speed of 9.8 meters (0.0061 miles) per second, which means that a fall of one kilometer (0.6 mile) would take 14, 3 seconds. Although much larger than our home planet, Saturn’s gravitational pull is only slightly stronger and produces a falling speed of 10.4 meters (0.0065 miles) per second. As such, it would take 13.8 seconds for a bullet to fall to the surface of the gas giant with the rings.

“It may be surprising to see the large planets have comparable attraction to the smaller ones on the surface,” O’Donoghue said on Twitter. “For example, Uranus shoots the bullet slower than on Earth! Why? Uranus’ low average density moves the surface away from most of the mass.

Ultimately, it is the density of an object, rather than its mass, that determines how quickly a ball falls to its surface. This results in startling observations across the solar system. For example, as O’Donoghue explains, “Mars is almost double the mass of Mercury, but you can see that the surface gravity is actually the same, indicating that Mercury is much denser than Mars.”

As the animation indicates, ball games are likely to be particularly difficult in the sun, as free-falling objects move at a staggering speed of 274 meters (0.17 miles) per second over our star, not taking only 2.7 seconds to fall to the surface from a height of one kilometer (0.6 mile) (assuming they did not vaporize). At the other end of the spectrum is the dwarf planet Ceres, the largest object in the asteroid belt between Mars and Jupiter. A game of volleyball here would likely put most spectators to sleep, given that it takes 84.3 seconds for a ball to gently rise to the surface.

It should be emphasized that the size and mass of the ball does not matter, because in the absence of any air resistance, all objects fall at the same speed. This was demonstrated by Apollo 15 astronaut David Scott, who dropped a hammer and feather from an equal height on the moon in 1971, confirming that they both reached the ground at the same time.