How much does something weigh? This is an important question in everyday life, whether it is deciding to try to pick up a piece of furniture or add more resistance during our workout at the gym. However, the better question to ask may be, how much mass does that object contain?
The reason this change in vocabulary can be important is that mass refers to the amount of stuff in an object. Weight, on the other hand, is an object's mass multiplied by the acceleration caused by gravity. On the Earth's surface, there's a consistent tug from gravity. However, if you venture to other planets where gravitational forces are different or into space itself where gravity is virtually non-existent, then that object's weight will change.
Mass, however, does not change no matter what the environment. For example, the mass of 263 kg, which stands as the current Olympic record for the clean-and-jerk, is the same in Rio as it would be on the Moon. It might be harder to lift it here on Earth with the stronger gravity, but the mass of those plates and bar remain constant because it is an independent value.
On Earth, there are some pretty massive things. The mass of an automobile is about 1,000 to 2,000 kg, while the blue whale is estimated to have a mass of nearly 200,000 kilograms. Humans have gone even further, constructing structures of enormous mass. The Golden Gate Bridge in San Francisco has the mass of about 380 million kg. That pretty big to be sure, but things can get much, much bigger.
Whale credit: NOAA Photo Library; Golden Gate Bridge credit: Ryan J. Wilmot
But how do we get the mass of objects that we can't physically move or even touch? One way is to observe how much gravitational pull it exerts on other objects or vice versa. Astronomers use this technique to measure the mass of some really enormous things.
Our planet Earth is 6 trillion trillion kilograms, which is a six followed by 24 zeroes. Our Sun is about a million times more massive than that, and the numbers keep going up. For example, the most massive cluster of galaxies in the early Universe that we know about is called El Gordo. Astronomers estimate that it contains the mass of some 3 million billion times the mass of our Sun.
The range of mass in our everyday lives and what we can appreciate in sporting events like the Olympics is just the tip of the proverbial iceberg – especially once we allowed our minds to consider the wonders of space.
