Scientific legend has it that a young Galileo Galilei conducted an experiment that helped to define some of the properties of gravity. In order to test Aristotle’s notion that objects fall at different rates according to their weight, Galileo is reputed to have taken two balls with materially different weights to the top of the Leaning Tower of Pisa and dropped them simultaneously. According to the story, the balls fell to the ground below at the same rate of acceleration and landed at the same time — thereby showing that Aristotle was wrong and the invisible force of gravity acts equally on objects with different masses. Galileo’s findings still hold up — even when modern-day scientists test the effects of gravitational acceleration at the atomic level.
I conducted my own impromptu experiment with gravity yesterday morning, and can attest that gravity is still out there, working the same way it always has.
I was just starting my morning walk. We had been subjected to the dreaded “wintry mix” overnight, and the footing was treacherous. The parking lot at the corner had been cleared of snow and looked to be dry and safe, so I decided to take a short cut through the parking lot. As I proceeded with a jaunty step across the lot, my right foot hit a patch of black ice, my feet shot out to the left, and I landed hard on the asphalt surface on my right side. I gingerly picked myself up, checked to make sure that I was in one piece, then carefully made my way back to our house, figuring that the wise course would be to skip any further icy adventures that day. Fortunately, I had on several layers as well as my own more than ample personal padding, no bones were broken, and I’m sore, but not badly bruised.
It’s the first time I’ve fallen to the ground in a while, and it got me to thinking how amazing gravity is. I probably fell no more than a few feet, but I struck the pavement with breathtaking (literally) force, as if one of the Ohio State linebackers had hit me at full speed and laid a crushing blow on my right side. The experience made me think that I need to be a lot more judicious about walking during the winter, because gravity is always out there, brooding and ready to yank you down.
I’m just grateful I wasn’t falling from the top of the Leaning Tower of Pisa.
First launched in 1997, Cassini has been knocking around the outer reaches of the solar system for years, exploring Saturn and its moons, and it has made some interesting discoveries. Cassini’s foray into Saturn’s rings will be its grand finale. The spacecraft will dive into the gap between Saturn and its rings, loop around the planet’s poles, and take a closer look at Saturn’s idiosyncratic features and study the gas and dust particles that make up the rings.
The mission then will close with Cassini flying close to the planet’s surface and ultimately plummeting into Saturn’s atmosphere in a final suicidal act. By then, Cassini will be out of fuel, and scientists don’t want to take the chance that the spacecraft could somehow crash into one of Saturn’s moons — moons that might be habitable — so Cassini will be intentionally steered into the planet to go out in a blaze of glory.
Saturn’s rings were first seen by humans in 1610, when Galileo Galilei turned his telescope to the night sky, and they have been the object of wonder and fascination ever since. The final stages of Cassini’s two-decade mission will give us more information about the rings than we have ever had before. And it may answer some nagging questions, like whether the rings are the same age as the planet itself, or were they formed later? And are there small moons embedded in the rings that might explain their shape and configuration?
NASA’s unmanned space exploration program should be the source of pride to all Americans. Through countless missions to the inner and out solar system, it has added exposed our planetary neighborhood as a constantly surprising place, with potential sources of water, rich mineral deposits, and places that might conceivably harbor other forms of life. The Cassini mission is just the latest chapter in an ever-encouraging tale that shows that the human impulse to explore and discover still runs strong.
There’s an Ohio connection to this story about Galileo, science, and the BBC, too: the room where the BBC does the experiment at the NASA Space Power Facility in Sandusky, Ohio, which features the largest vacuum chamber in the world.