Objects with mass have a gravitational attraction between them. A basketball has a gravitational interaction with Earth (since they both have mass).

The mass of an object tells you how heavy something is. You can measure mass in grams (g) and kilograms (kg). Light items, like apples and bananas, are measured in grams. Heavy objects, like a toy ...

So, astronomers can measure one or both of these quantities to derive the mass of a galaxy’s central supermassive black hole.

Your iPhone or iPad can use the free Measure app to take basic measurements. If you have a newer device, you may have more complex measuring options.

Researchers measure the gravity exerted by a 90 milligram object We've measured the pull between two gold spheres, each 2 millimeters across.