People believed to be dead live longer

planets, star

Presumed witness to a cosmic collision: The planet Halla, 532 light-years away, may once have orbited two closely spaced stars – even as matter fell from one to the other. When the stars merged, Halla was not swallowed but continues to orbit the merger product to this day.
©Illustration: WM Keck Observatory/Adam Makarenko

When a star like the Sun expands into a red giant, it engulfs its nearby planets. However, astronomers have now discovered satellites past this final stage.


In around 7.5 billion years, the sun has used up the hydrogen supply in its central region. Then shrinks

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