Orbital Obliteration
Changes in how the planets circle the sun could also knock out Earth.
Jupiter is the most massive planet in the sun’s posse. As such, it tugs at the orbits of the other planets. Over millions of years, the gaseous giant could bully tiny Mercury’s elliptical orbit so much that the farthest distance it travels away from the sun increases, and the closest point gets closer.
As Mercury’s orbit stretches, the swift planet could crash into the sun, according to a 2008 study in the Astrophysical Journal. Alternatively, Mercury could cross Venus’ orbit and then “there’s a very short time until there’s a real disaster,” said UCSC astronomer Greg Laughlin, one of the study’s authors. Venus and Mercury’s kiss of death, he said, “could eject Mars from the solar system.”
But in the worst-case scenario, Mercury and Earth could collide. The impact would destroy Earth even though our planet has about 20 times the mass of Mercury.
Thinking about “orbits going unstable adds a little spice of danger” to planetary science, Laughlin said. But there’s only about a 1 percent chance any of these situations will pan out in the next 5 billion years.
mage courtesy of Lynette Cook for the Gemini Observatory/AURA