Have you ever wondered about the possibility of playing football on different planets within our solar system?
On the 11th of this month, Dr. James O'Donoghue, a planetary scientist at JAXA, posted on his YouTube channel a video in which he shows how fast an object, such as a ball, falls on different surfaces of planets in the world. Our solar system, including the Sun, Moon, Earth, Jupiter and Pluto, as well as the dwarf planet Ceres, which lies within the asteroid belt between Jupiter and Mars.
According to the report published on the Science Alert website, the video is based on data sourced by NASA.
Density and gravitational force
It can be surprising to see large planets with a similar gravitational pull to smaller ones, as the video shows a ball falling from a distance of one kilometer towards the surface of each planet, assuming there is no air resistance.
Here, we see that a ball thrown from a distance of one kilometer takes 2.7 seconds to travel that distance and fall on the Sun, while it takes 14.3 seconds to fall on Earth, and the ball in question takes 13.8 seconds to fall on Saturn, and 15 seconds on Uranus.
This can be explained by the gravitational force that is specific to each planet, which is related in one way or another to the density of the planet itself.
The density of the planet expresses the ratio between the mass of the planet to its size, and the density of the planets is measured in relation to the density of water.
Surprisingly seeing large planets have a gravitational pull similar to smaller ones (Wikimedia)
This means that Uranus pulls the ball down more slowly than Earth does!
Because the average density of Uranus is much lower than the density of the planet Earth, which ranks among the list of the most dense planets.
Similarly, Mars is roughly twice the size of Mercury, but they are similar in terms of gravity and this indicates that Mercury is denser than Mars.
Indeed, the calculations show that Mercury's density is estimated at 5.3, while the density of Mars is estimated at 3.9 times the density of water.
The dwarf planet Ceres ranked last in the list of planets under experiment, as it took the ball 84.3 seconds to fall from a distance of one kilometer on its surface, and the density of the dwarf planet is estimated at 2 times the density of water.
The video shows a ball falling from a distance of one kilometer towards the surface of each planet (Wikimedia)
No effect of mass
O'Donoghue also referred to one of the most famous gravity experiments ever conducted, that of astronaut Dave Scott on the Moon, which shows that all objects fall at the same rate (regardless of mass) provided there is "no air resistance".
If we drop a feather and a hammer on the moon from the same height at the same time, they will both land on the moon at the same time as well.