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The Sun Has Reached Middle Age

It's in a stable, staid state — for now

circa 1970:  A white California sun in a yellow sky rides above orange mountains.  (Photo by Ernst Haas/Ernst Haas/Getty Images)
Ernst Haas/Getty Images

Over 83 million Americans are in middle age, though it turns out they’re not the only ones. Seems the sun has reached that milestone too, at the ripe old age of 4.57 billion years, according to the European Space Agency (ESA). And just like many people in the middle stage of their lives, the sun is in a stable — even staid — state, fusing hydrogen into helium.​​

​That won’t always be the case. Using data collected by the ESA’s star-mapping Gaia mission, astronomers predict the sun will reach its maximum temperature when it’s about 8 billion years old. After that, at the age of 10 to 11 billion years, it will cool down and swell into a huge red star, lowering its surface temperature along the way. The sun will then reach its end-of-life phase and eventually become a dim white dwarf, according to the ESA.​​

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High-definition images provide insight into trajectory​

​Astronomers base these predictions and more on the images Gaia collects, which record the star’s brightness and color. Astronomers — including Orlagh Creevey of Observatoire de la Côte d’Azur, France, and collaborators from Gaia’s Coordination Unit 8 — painstakingly determine astrophysical parameters from those images. Finding stars that are similar to the sun was the main focus for understanding how we fit into the universe. “If we don’t understand our own sun — and there are many things we don’t know about it — how can we expect to understand all of the other stars that make up our wonderful galaxy,” says Creevey in the report.​​

​Sun characteristics in middle age​

​Characteristics of our middle-age sun include the following:​

  • Frequent solar flares. A solar flare is an intense eruption of electromagnetic radiation in the sun’s atmosphere. These eruptions can damage satellites, radio communications and power-system infrastructure. They can’t harm humans.​​
  • Coronal mass ejections. CMEs are large explosions of plasma and magnetic fields from the sun’s corona, the outermost part of the sun’s atmosphere. They travel outward at speeds ranging from 250 kilometers per second to 3,000 kilometers per second, according to the National Oceanic and Atmospheric Administration. They can cause surges in electric currents on Earth, leading to blackouts. In 1989, a CME and a solar flare caused a blackout that affected all of the Canadian province of Quebec. NASA said it lasted 12 hours.​
  • Solar storms. These are a combination of solar flares and CMEs that can make satellites disappear, disrupt telecommunications and interfere with navigation systems. Solar storms also can cause blackouts in cities and even regions, according to EarthSky, a science website.​