Word: orbitals
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...need to cash in your IRA quite yet. For one thing, today doesn't have the closest alignment of planets in 6,000 years; in fact, the alignment has often been closer, very much so in 1861. For another, the changing distance of the moon in its monthly orbit has many times the gravitational effect on the earth of all of the planets combined. One would thus expect this kind of "polar shift" several times a week...
...collision course with Earth. The sudden appearance of long-period comets, usually larger and with better than twice the impact velocity of asteroids, presents an even greater menace. Such objects (comet Hale-Bopp was one) are usually not spotted until they begin to flare somewhere out near the orbit of Jupiter or closer, only a few to 18 months before they pass Earth's orbit. That doesn't leave much time for defensive measures. Then, too, only a tiny fraction of the more numerous and smaller NEOs, some of them potential city killers and tsunami producers, are yet known...
NEOs are asteroids or occasional comets that periodically intersect or come close to Earth's orbit. If a NEO cuts through our orbital path at the same time that Earth happens by, it's curtains for a metropolitan area, a region or even global civilization, depending on the size of the interloper...
...made nuclear explosions to pulverize a small asteroid or deflect a larger one. Given enough time, and under the proper circumstances, less drastic measures would be needed. Some schemes call for conventional explosives alone, or anchoring a rocket motor or a solar sail on an asteroid to alter its orbit enough to allow it to safely bypass Earth...
...both ways at 99.995% the speed of light. When you return, the earth will be 1,000 years older, but you'll have aged only 10 years. I already know a time traveler. My friend, astronaut Story Musgrave, who helped repair the Hubble Space Telescope, spent 53.4 days in orbit. He is thus more than a millisecond younger than he would have been if he had stayed home. The effect is small, because he traveled very slowly relative to the speed of light, but it's real...