Dr. James O’Donoghue, a Japan-based planetary scientist, has made some incredible educational astronomy videos before. Including a video that showcases relative cosmic velocities to understand better how fast things are moving in space. And, in another video, he demonstrates the rotational rates of different planets. Recently, he added a look at gravity’s strength on the different planets in the solar system. Even Pluto!
Boing Boing picked up on O’Donoghue’s new video, which he recently released on his YouTube channel. As he notes in the video’s description, the animation shows a ball dropping from 1,000 meters—or approximately 3,280 feet—above each planet, the Sun, and Pluto.
As the video demonstrates, the Sun’s immense average density means that its own ball falls far faster than all the others. Indeed, O’Donoghue notes that each individual celestial body’s average density determines its gravitational pull. And therefore, how rapidly objects fall to its surface. Conversely, O’Donoghue has also shown how fast one would need to travel to escape the gravitational pull of different planets. (The comparison is in the tweet below.)
How fast you need to go to escape each Solar System object, shown over 50 km pic.twitter.com/KbwCyCEoVr— Dr. James O'Donoghue (@physicsJ) July 18, 2021
O’Donoghue shows that because the average density is what matters for a body’s gravitational pull, large planets can have a pull comparable to smaller ones. So, for example, even though Saturn is far larger than Neptune, both planets’ balls fall at about the same rate.
Another fun aspect to consider when watching the video is just how fast each ball is falling. Jupiter’s gravitational pull rockets its ball up to nearly 500 mph. Although the Sun’s gravitational tug dwarfs that with its ball flying at nearly 1,600 mph straight at its surface.
Dr. James O’Donoghue
For anyone who’s looking to keep their head in space, we recommend checking out more of O’Donoghue’s videos. Plus,, there are always tons of exoplanets to check out. Including ones that might have—quite dense—diamond crusts.
Feature image: Dr. James O’Donoghue