Our sun is 4,500,000,000 years old. That's a lot of zeroes. That’s four and a half billion.
How do we know how old it is? We look at the age of the whole solar system, because it all came together around the same time.
To get this number, we look for the oldest things we can find. Moon rocks work well for this. When astronauts brought them back for scientists to study them, they were able to find out how old they are.
If our Sun is four and a half billion years old, how much longer will it shine? Stars like our Sun burn for about nine or 10 billion years. So our Sun is about halfway through its life. But don’t worry. It still has about 5,000,000,000—five billion—years to go.
When those five billion years are up, the Sun will become a red giant. That means the Sun will get bigger and cooler at the same time. When that happens, it will be different than the Sun we know today. As a red giant, our Sun will become about 2,000 times brighter than it is now!