About a billion years from now, the sun will have become much bigger, brighter and hotter, likely leaving Earth uninhabitable. However, a chance encounter with a passing star could save our planet by tossing it into a cooler orbit or helping it break free of the solar system entirely, a new theoretical study suggests. (Still, the chances of that happening are extremely slim.)
Today, Earth lies within the sun's habitable zone, a ring-shaped region within which planets may harbor liquid water. But our planet's situation will worsen as the sun grows over the next billion years, pushing this zone outward and away from Earth. That means liquid water — and, therefore, life — could become history well before the sun balloons into a red giant and swallows Earth entirely 5 billion years from now.
