Like everything else in nature, astronomical objects change and evolve in time. Take our sun, for instance. When it first formed, our sun slowly fused hydrogen into helium, just like a hydrogen bomb. As it aged, it became more compact which increased the rate of hydrogen fusion in its core. It now emits 30% more energy than when it first started starting fusing hydrogen.
As the hydrogen fuel is slowly consumed, the helium “ash” builds up in the core causing the hydrogen fusion area to move closer to the surface. This heats the surface of our star causing it to swell, making the sun expand. Eventually, our sun, as do all stars like it, will evolve into a red giant star, one hundred times larger than it is now.
Our sun as a red giant star, scorching Earth. Credit NASA.
At that point, our star’s surface will extend farther than Earth’s current orbit, swallowing Mercury and Venus, the planets closer to the sun than Earth. It’s not automatic that Earth will be consumed by the growing sun. As the sun grows, it blows off more and more material as solar wind. As the sun’s mass decreases, Earth will slip farther out. But even if Earth survives, and most astronomers think it won’t, our planet will become so hot that the oceans will boil and fires will consume all life on the planet.
Earth being destroyed by Red Giant sun. Credit NASA.
By studying the light spectrum of stars, astronomers can measure their chemical makeup. The chemical abundances of some stars in our galaxy at a more advanced stage of stellar evolution than our sun reveal that planets once orbiting that sun have been engulfed and destroyed in the fiery atmosphere of the star. They find elements in the star that can only have come from orbiting planets. They can see that these suns devour their planets as they age and grow larger, just as our sun will do one day.
Alien astronomers on other planets studying our solar system a few billion years in the future will be able to detect the remnants of Mercury and Venus. Will they also detect the remnants of Earth? We don’t yet know for sure, but we do that we humans will have either perished or moved out into space in search of Earth 2.0.
Each month, I write an astronomy-related column piece for the Oklahoman newspaper. On the following day, I post that same column to my blog page.
This is reprinted by permission from the Oklahoman and www.Oklahoman.com.
