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The Magazine News Observing. The scientists say the discovery is in keeping with previous calculations that more than half of white dwarf stars may have similar giant planets orbiting them. Though the phenomenon had been predicted, it had never been observed before.
Blackman said the discovery shed light on what will happen when the sun runs out of fuel. In five billion years, the sun is expected to expand, becoming what is known as a red giant. Earth may survive the event, but will not be habitable. Once the sun completely runs out fuel, it will contract into a cold corpse of a star — a white dwarf. Themiya Nanayakkara, an astronomer at the Swinburne University of Technology who was not involved in the research, said the discovery suggested outer gas giant planets like Jupiter and Saturn could survive the death of the sun.
The size of a star determines what it eventually turns into: bigger, heavier stars may end up as black holes or neutron stars instead. Sign up to receive an email with the top stories from Guardian Australia every morning. That release of energy results in more light and heat, making the sun even brighter.
On a darker note, however, the energy also causes the sun to bloat into a red giant. Red giants are red because their surface temperatures are lower than stars like the sun. Even so, they are much bigger than their hotter counterparts. The whole process of turning into a red giant will take about 5 million years, a relative blip in the sun's lifetime.
On the bright side, the sun's luminosity is increasing by a factor of about 10 percent every billion years. The habitable zone, where liquid water can exist on a planet's surface, right now is between about 0. That zone will continue to move outward. By the time the sun gets ready to become a red giant, Mars will have been inside the zone for quite some time.
Meanwhile, Earth will be baking and turning into a steam bath of a planet, with its oceans evaporating and breaking down into hydrogen and oxygen. As the water gets broken down, the hydrogen will escape to space and the oxygen will react with surface rocks.
Nitrogen and carbon dioxide will probably become the major components of the atmosphere — rather like Venus is today, though it's far from clear whether the Earth's atmosphere will ever get so thick. Some of that answer depends on how much volcanism is still going on and how fast plate tectonics winds down.
Our descendants will, one hopes, have opted to go to Mars by then — or even farther out in the solar system. But even Mars won't last as a habitable planet. Once the sun becomes a giant, the habitable zone will move out to between 49 and 70 astronomical units. Neptune in its current orbit would probably become too hot for life; the place to live would be Pluto and the other dwarf planets, comets and ice-rich asteroids in the Kuiper Belt.
Planets' orbits around the sun will slowly expand.
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