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Hank tells the story of the mysterious star known as "Methuseleh," and why scientists think that it is the oldest known star in the universe.

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Watch Galaxies Collide:
Strange 'Methuselah' Star Looks Older Than the Universe:
Hubble Finds Birth Certificate of Oldest Known Star:
Hank: We know a shocking amount about the universe, considering that we can only observe it from this one tiny point in space that is our planet. The fact that we're able to calculate the age, composition, and speed of stars, or that we can know what the universe is made of and how old and big it is, it's pretty freaking cool. All of that knowledge is based on observations and calculations and sometimes, it's wrong. Consider HD 140283, or the Methuselah Star, which according to initial calculations, is about 2 billion years older than the universe. (SciShow Intro plays) So, obviously someone's got something wrong here, and it's almost certainly the age of this particular star, not our supposed age of the universe, which is pretty well set. When it was first measured in the year 2000, its distance to us combined with the measurements of its brightness and composition indicated that it was about 16 billion years old, curious, the considering that the universe started existing 13.7 billion years ago. So the question is, what did we do wrong here, was it in the measurements or in our calculations, or were we wrong about how stars form or could this particular star have had a weird life story or are we wrong about everything we thought we knew and it turns out in fact that our planet is just covered in a piece of black fabric with little holes poked in it? Turns out, it's actually a combination of a number of those things, definitely not the last one though. The Methuselah star was not always part of our Milky Way, 12 billion years ago, a smaller galaxy collided with, and became part of, ours. Methuselah was one of the stars of that other galaxy, which accounts for its intense speed, some 1.3 million kilometers per hour, as well as its strange galactic orbit. It also may be why the star has been a bit confusing to us. When astronomers turned the Hubble Space Telescope on this galactic mystery, we found that the star had a different composition than we first assumed, with a higher oxygen:iron ratio. Hubble was also able to gauge its distance more accurately, bringing the suspected age down to just 14.5 billion years old, plus or minus 800 million years. That, barely, gets the star into the realm of being possible, but there are still many things that we do not know about star formation and their aging process, and everyone is confident that HD 140283 is not, in fact, older than the universe. The extreme age of this star is nonetheless fascinating and can tell us many interesting things. The first generation of stars that formed after the Big Bang were not long lived, most going nova within a few million years. Methuselah must have been of the second generation of stars, and it's age being so close to the birth of the universe indicates that the space between the formation of the first and second generations of stars was only a few tens of millions of years. At the moment, HD 140283 is the oldest known star in the universe, and while that's not quite as impressive as being older THAN the universe, it's still a pretty cool superlative. Thank you for watching this episode of SciShow, and thank you for suggesting this as a topic for us to cover. If you have other things that you would like us to talk about, please, we're on Facebook and Twitter and of course, down in the comments below, and if you want to keep getting smarter with us here at SciShow, you can go to and subscribe. (SciShow Endscreen)