Methuselah Is The Oldest Known Star And Estimates Say Its Age Is 16 Billion Years Old. But How Can That Be When The Age Of The Universe Is 13.8 Billion Years Old?

The Big Bang theory (the actual theory, not the TV show) says that the universe is about 13.8 billion years old. Therefore, anything within the universe must be younger than that, right?

Yes, of course. Which is why it was especially surprising when astronomers estimated the age of a star that was named Methuselah to be 16 billion years old.

This star is scientifically named HD 140283, but is nicknamed Methuselah, which is the name of Noah’s (from Noah’s Ark fame) father, who the Bible records as living to 969 years old.

It was first identified in the 1950s and was determined to be about 200 light-years away from Earth. After years of study, it was found that the star had very low metal content, which indicates that it is quite old. Older stars have less metal in their cores because in the early universe, metals hadn’t yet formed.

This star is also moving very quickly. NASA’s Hubble Mission team explained what this means:

“The high rate of motion is evidence that the star is simply a visitor to our stellar neighborhood. Its orbit carries it down through the plane of our galaxy from the ancient halo of stars that encircle the Milky Way, and will eventually slingshot back to the galactic halo.”

When astronomers tried to determine the age of this star, they got an unexpected result. Using standard stellar aging techniques, they came up with an age of about 16 billion years.

If the age of the universe itself is just 13.8 billion years, something is wrong. Maybe the star isn’t that old, or maybe the universe is older. Either way, they needed to figure this out.

So, the astronomers went to work gathering more precise data about the star. Howard Bond of Pennsylvania State University in University Park and the Space Telescope Science Institute in Baltimore put out a statement about this effort in 2013:

“Maybe the cosmology is wrong, stellar physics is wrong, or the star’s distance is wrong. So we set out to refine the distance.”

After gathering more precise information, it was determined that the star is 190.1 light-years away. Closer than previously thought, but not by that much. The team also found that the star had a higher oxygen-to-iron ratio than previously thought. This brought the age estimates down. Bond explained:

“Put all of those ingredients together and you get an age of 14.5 billion years, with a residual uncertainty that makes the star’s age compatible with the age of the universe. This is the best star in the sky to do precision age calculations by virtue of its closeness and brightness.”

While a 14.5 billion-year-old star is still technically older than the 13.8 billion-year-old estimates for the universe, it falls within the margin of error. Maybe the universe is slightly older than commonly stated, maybe the star is slightly younger. When dealing with things this old, it is easy to be off by a matter of millions of years.

Another estimate puts the star between 11.5 and 12.5 billion years old. Regardless of its exact age, one thing is certain: it is an extremely old star.

Having a star this old, close enough to study, gives astronomers a great opportunity to learn more about what the universe was like near the beginning.

If you thought that was interesting, you might like to read about a second giant hole has opened up on the sun’s surface. Here’s what it means.