Year+13+Gravitation+and+Orbit

media type="custom" key="8729708" media type="custom" key="8729600"



**Changing Orbit Could Save the Planet ** **Scientists Say Adjusting Earth's Path Could Rescue It From the Dying Sun **  In about 5 billion years, the dying sun will expand, obliterating all life on Earth. But we could avoid that fate, says a group of astrophysicists, if we just widen our planet's orbit, bit by bit, over time.

"We started thinking that if you could move the Earth, you could buy some time," says Don Korycansky, lead author of a recent paper in Astrophysics and Space Science and a researcher at the University of California at Santa Cruz. He and two other scientists propose gradually shifting Earth's orbit to keep pace with the expansion of the sun.

**Shooting an Asteroid ** The scientists say the change in orbit must be incremental to match the slow transformation of the sun into a red giant — an expanding, but dying, star. "You don't want to move the Earth all at once because it would be too cold," Korycansky says. The theory calls for carefully rocketing an asteroid or other object past Earth within 10,000 miles. The close pass of the asteroid would pull our planet slightly away from the sun — about 30 miles from its original orbit, the scientists estimate. "They would sort of tug at each other," says Korycansky. Known as "gravity-assist," the technique is already used by space programs to propel space probes through the universe by swinging them past other planets. But to keep tempo with the heating sun, the scientists estimate the measure would need to be repeated every 6,000 years. Over time, the migration could eventually add another 6 billion years to the lifespan of the planet, according to the study. Without any intervention, Earth's oceans will evaporate, until the surface of the planet resembles Venus, a dry, barren planet.

**Not a Solution for Global Warming ** It might even be possible to use the same asteroid for each stage of the migration, the scientists say, by swinging the asteroid back and forth between another planet, like Jupiter. "In a sense you would be transferring energy from Jupiter to Earth," Korycansky says. That would save on the energy and cost of needing to harness a new asteroid for each procedure.

And while moving the planet might be an option for escaping the sun's wrath, it's not a solution to the problem of global warming, the scientists emphasize. The theoretical solution to the danger of the sun will need millions of years to implement. The problem of climate change caused by carbon dioxide, they say, is too immediate.