Description: Earth exerts a force known as gravity, which pulls all objects towards Earth's center. On or near Earth's surface, we experience that force as pulling us and everything else downward. For any object, the strength of the downward-pulling force is called that object's weight. On any given planet, an object's weight is directly proportional to the object's mass, and in everyday life we sometimes use the terms weight and mass interchangeably. When we use bathroom scales, those measure the force pushing down on them. If we are standing still on the scales and not pushing or pulling on another object this force is our weight, but the scales give us the results as a value for our mass, in kilograms, pounds, or another mass unit. But if we stood on the Moon, or on the surface of another planet, our mass would still be the same, but our weight would be different, so it's important to keep the two terms apart!

Related Terms:

• Gravity
• Mass

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".