About the image. Drawn as a yellow-white star about twice as wide as the Sun, with a scattering of old orange stars around it like the galactic halo it comes from. Surface detail is imagined.
In the constellation Libra, just too faint to see with the naked eye, is a star with the plain catalogue name HD 140283. Through binoculars it looks like nothing special. But it is one of the oldest stars known, and for a while it seemed to be older than the universe itself. That earned it the nickname “the Methuselah star”, after the longest-lived man in the Bible.
A visitor from the halo
HD 140283 is poor in heavy elements. Stars inherit the elements of the gas they form from, and the earliest stars formed when the universe held almost nothing but hydrogen and helium. HD 140283 has only about a 250th of the Sun’s share of iron and other heavy elements, a sign that it formed very early. It does not belong to the Milky Way’s disc at all: it is a member of the halo, the old cloud of stars around our galaxy, and is passing through our neighbourhood at high speed on a long, plunging orbit.
Older than the universe?
A star’s age can be worked out from how bright it really is, which requires knowing its distance precisely. Early estimates gave HD 140283 an age of up to 16 billion years, impossible in a universe less than 14 billion years old. In 2013 Howard Bond and colleagues used the Hubble Space Telescope to measure its distance much more accurately and found an age of 14.46 billion years, with an uncertainty of about 0.8 billion years. That still nudged past the age of the universe, 13.787 billion years, but the ranges overlapped, so there was no real contradiction.
Later studies have pulled the figure back. In 2014 Don VandenBerg and colleagues found 14.27 billion years. In 2021 Jieun Tang and Meridith Joyce, using improved models, estimated about 12 billion years. Other recent work gives values from 12 to 14 billion. The exact age depends on details of how stars evolve that are still being refined.
Why it matters
Whatever the final number, HD 140283 formed within the first couple of billion years after the Big Bang, and it is still shining today. Stars like it are a check on cosmology: the universe cannot be younger than the oldest stars in it. So far, the Methuselah star has always come out just inside the limit.
To scale · radius, Sun = 1Sun: 1.00 · HD 140283: 2.14
How hot is it?
Earth (average)288 K · 15 °C
Water boils373 K · 100 °C
Venus surface737 K · 464 °C
Iron melts1 811 K · 1 540 °C
Sun's surface5 772 K · 5 500 °C
Methuselah star (HD 140283)5 787 K · 5 510 °C
Methuselah star (HD 140283): surface temperature. Logarithmic scale from 100 K to 10 000 K. Reference values: NASA, IAU.
How long to get there?
Methuselah star (HD 140283) is about 200.5 light-years away.
Light299 792 km/s201 years
Breakthrough Starshotplanned light sail, 20% of light speed1 003 years
Parker Solar Probefastest spacecraft so far, 192 km/s313 064 years
Voyager 1leaving the Solar System, 17 km/s3.5 million years
At Voyager 1's speed the trip would take about 44 197 human lifetimes of 80 years. Bars are on a logarithmic scale. Speeds: NASA, Breakthrough Initiatives.
Gallery
A single yellow-white star shining above the thin, edge-on band of a spiral galaxy, an impression of the Methuselah star high in the halo of the Milky Way. AI-generated painting.A spiral galaxy seen at a slant, with a single bright star alone in the dark space above it, an impression of the Methuselah star travelling through the halo of the Milky Way. AI-generated painting.Methuselah star (HD 140283), 3D artist's impression, rendered from the interactive model.Methuselah star (HD 140283), 3D artist's impression, from another angle, rendered from the interactive model.Methuselah star (HD 140283), 3D artist's impression, close-up, rendered from the interactive model.
Timeline
1951Shown to be very poor in heavy elements.
2013Hubble distance gives an age of 14.46 ± 0.8 billion years.
2014Revised to 14.27 billion years.
2021New models give about 12 billion years.
Questions people ask
Is the Methuselah star older than the universe?
No. Some estimates came out slightly older, but within their uncertainties they agree with the universe's age of 13.8 billion years. Newer estimates are lower.
Can I see the Methuselah star?
With binoculars. It is magnitude 7.2, in the constellation Libra.
What is the oldest star?
HD 140283 is among the oldest known, formed within the first couple of billion years after the Big Bang.