{"id":630911,"date":"2026-09-21T00:00:14","date_gmt":"2026-09-21T00:00:14","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/630911\/"},"modified":"2026-09-21T00:00:14","modified_gmt":"2026-09-21T00:00:14","slug":"people-think-earth-dies-when-the-sun-becomes-a-red-giant-in-five-billion-years-the-more-likely-end-is-a-billion-years-from-now-when-a-star-already-30-percent-brighter-than-at-birth-pushes-c","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/630911\/","title":{"rendered":"People think Earth dies when the Sun becomes a red giant in five billion years \u2014 the more likely end is a billion years from now, when a star already 30 percent brighter than at birth pushes CO\u2082 too low for C3 plants, then a moist greenhouse strips the oceans of hydrogen and leaves a sterile Venus"},"content":{"rendered":"

The Sun<\/a> is roughly 4.6 billion years old and about halfway through its main-sequence lifetime.<\/p>\n

The popular conception holds that Earth\u2019s destruction will come when the Sun becomes a red giant roughly 5,000,000,000 years from now, but Earth may become uninhabitable billions of years before that\u2014not because of a sudden solar catastrophe, but because of the normal evolution of an ordinary star.<\/p>\n

\ufeff<\/p>\n

As the Sun ages, it gradually becomes brighter and more luminous.<\/p>\n

Roughly 1,000,000,000 years from now, increased solar output could push Earth\u2019s climate outside of the envelope that allows life to exist here. What does this look like?<\/p>\n

The oceans evaporate. Water vapor increases.<\/p>\n

Plant life dies.<\/p>\n

And eventually, Earth transitions from the vibrant blue planet we know today into something<\/a> closer to Venus<\/a>\u2014incapable of supporting life<\/a> as we know it.<\/p>\n

Getting Hotter as it Ages<\/p>\n

The Sun<\/a> is powered primarily by nuclear fusion in its core. Four hydrogen nuclei ultimately combine to form helium through the proton-proton chain, converting a small amount of mass into energy.<\/p>\n

Every second, the Sun converts roughly 600 million metric tons of hydrogen into helium. Over billions of years, helium accumulates in the Sun\u2019s core.<\/p>\n

The mean molecular weight of the core increases, and the core slowly contracts under gravity.<\/p>\n

\"Venus<\/p>\n

Venus Transit In Front of the Sun NASA Photo<\/p>\n

Contraction raises the temperature and pressure.<\/p>\n

The higher core temperature increases the fusion rate in surrounding hydrogen-rich material.<\/p>\n

The result may seem counterintuitive: as the Sun exhausts its hydrogen, it becomes more luminous.<\/p>\n

One might expect the Sun to grow dimmer as this process plays out, but that\u2019s not the case.<\/p>\n

The Sun today is estimated to be roughly 30 percent brighter than when it formed.<\/p>\n

It should continue to become roughly ten percent more luminous per billion years during this phase.<\/p>\n

Testing Earth<\/p>\n

So far, the Earth has survived billions of years of increasing solar luminosity because our climate isn\u2019t just passive.<\/p>\n

The carbonate-silicate cycle acts as a geological thermostat over eons. So the Earth<\/a> can adjust to the Sun\u2019s changing levels of dimness or brightness.<\/p>\n

But this mechanism has limits. Eventually, the Sun will become too bright to handle.<\/p>\n

\"Space<\/p>\n

Space Shuttle Discover. 19FortyFive Image Taken at the Smithsonian.<\/p>\n

\"Space<\/p>\n

Space Shuttle Discovery at Smithsonian. 19FortyFive.com Original Image.<\/p>\n

\"Space<\/p>\n

Space Shuttle Discovery at Smithsonian. 19FortyFive.com Original Image.<\/p>\n

As the Sun brightens, the Earth needs less atmospheric CO\u2082 to maintain acceptable temperatures.<\/p>\n

But eventually, CO\u2082 concentrations will become too low for much of Earth\u2019s plant life, which would, of course, be catastrophic for all of us.<\/p>\n

Plant Death<\/p>\n

The Earth\u2019s biosphere could be the first thing to fail. Photosynthetic organisms require carbon dioxide.<\/p>\n

C3 plants (including most trees and many major crops) would struggle as atmospheric CO\u2082<\/a> declines.<\/p>\n

More CO\u2082-efficient C4 plants could last longer.<\/p>\n

But the loss of photosynthesis means declining plant biomass, oxygen production, and terrestrial food webs.<\/p>\n

Complex animals, like humans, depend on those systems.<\/p>\n

So the initial problem wouldn\u2019t be the Sun getting hotter and the oceans boiling.<\/p>\n

It would be more gradual, starting with the slow death of Earth\u2019s plant systems.<\/p>\n

Spiking CO\u2082<\/p>\n

As the Sun brightens and temperatures rise, evaporation would increase.<\/p>\n

This would lead to more atmospheric water vapor, which in turn would intensify the greenhouse effect and accelerate warming, restarting the cycle.<\/p>\n

This would lead to something scientists call a moist greenhouse, where large amounts of water reach the upper atmosphere.<\/p>\n

Today, because Earth\u2019s upper atmosphere is relatively cold, it keeps water below, mitigating the moist greenhouse effect.<\/p>\n

But with enough warming, more water would rise, where ultraviolet sunlight would break H\u2082O<\/a> apart into hydrogen and oxygen.<\/p>\n

Hydrogen, being so lightweight, could then escape into space, meaning Earth would lose the building block necessary to remake the oceans.<\/p>\n

Over time, water loss would become permanent. Again, that would be a problem for life on Earth.<\/p>\n

Five Billion Years<\/p>\n

Of course, the one-billion-year estimate is speculative; it\u2019s not an exact countdown.<\/p>\n

Climate models produce different estimates based on dozens of finicky variables.<\/p>\n

But either way, the Sun is dying. Five billion years from now, the Sun\u2019s hydrogen core will be depleted, and it will leave the main sequence.<\/p>\n

The core will contract while the outer layers expand, forcing the Sun to become a red giant. Mercury<\/a> and Venus<\/a> will be engulfed.<\/p>\n

Earth could be engulfed, too.<\/p>\n

Even if Earth weren\u2019t engulfed, the surface would be completely destroyed. Not that it matters, because by then, Earth will have been sterile for billions of years<\/a>.<\/p>\n

About the Author: Harrison Kass<\/p>\n

Harrison Kass is a writer and attorney focused on national security, technology, and political culture. His work has appeared in Tablet, City Journal, The Hill, The Spectator, and The Cipher Brief. He holds a JD from the University of Oregon and a master\u2019s in Global & Joint Program Studies from NYU. More at harrisonkass.com<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"The Sun is roughly 4.6 billion years old and about halfway through its main-sequence lifetime. The popular conception…\n","protected":false},"author":2,"featured_media":630912,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[3224,61,60,91,82,3630,247,1337,1770,7305,18312],"class_list":["post-630911","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-earth","tag-ie","tag-ireland","tag-nasa","tag-science","tag-solar-system","tag-space","tag-space-exploration","tag-space-science","tag-sun","tag-the-sun"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/630911","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=630911"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/630911\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/630912"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=630911"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=630911"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=630911"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}