J2000

J2000 is a really long word that grown-ups use to talk about time. It's like when you have a favorite toy, and you always remember when you got it. J2000 is like that, but for the earth! Grown-ups picked a special day and time to be the starting point for measuring time for the earth. They picked the day and time to be January 1, 2000, at exactly 12:00:00 in the daytime, but not the night time. This point is called J2000, and it's like putting a little mark on the calendar that everyone can agree on. Just like using a ruler to measure how tall you are, grown-ups use J2000 to measure things that happened on earth, like how long ago certain events occurred. It's a way to make sure everyone is talking about the same time, even if they are in different places on earth or talking about things that happened a long time ago.