Before Present

Before Present (BP) is a special way of measuring time that scientists use to talk about things that happened a long, long time ago.

You know how we use years to talk about how long ago something happened? Like, "I was born 5 years ago." Well, scientists have to talk about things that happened a lot longer ago than that! Sometimes they need to talk about things that happened thousands, or even millions, of years ago.

So, instead of using regular years, scientists use a special measuring system called Before Present. "Present" means right now, so "Before Present" means a time earlier than right now. For scientists, "present" means the year 1950.

Why 1950? Well, that's because the scientists who came up with this system decided that it would be easier to start measuring time based on when something happened to the Earth called the "bomb pulse". In 1945, scientists tested atomic bombs for the first time, and these bombs released a lot of carbon into the atmosphere. This carbon spread all over the world and was stuck inside plants, animals, and rocks.

Over time, the amount of this carbon in the atmosphere started to decrease because it was being absorbed by the Earth. By 1950, the amount of this carbon was lower than it was before the bombs were tested, so that's when scientists decided to start measuring time using 1950 as a reference point.

So, when scientists say something happened "1000 years Before Present," they mean it happened 1000 years before the year 1950. This system helps scientists talk about things that happened a really long time ago in a way that's easy to understand.