This summer, people saw Brood X cicadas emerge from their 17-year slumber, Venus crossing in front of the sun for the first time in 122 years and even, just last week, a so-called "blue moon."
Ah, the wonders of the natural world: In 2003, Mars moved closer to Earth than it's been in 60,000 years. In 1997, the great comet Hale-Bopp streaked overhead. In 1994, another comet, Shoemaker-Levy 9, crashed into Jupiter. And recent years have featured blooms of once-rare Sumatran "corpse flowers," which foul the air with the intense smell of rotting flesh.
"We're in a pretty fortunate era," says Donald K. Yeomans, a senior research scientist who manages NASA's Near-Earth Object Program office. "We're pretty lucky if we take the time to go outside and turn off the tube."
But no matter what you do, you'll never see it all.
Few alive now have ever seen Halley's comet in its prime. And you may never witness a truly massive meteor storm flash across the sky, or see Venus pass in front of Jupiter. There's only a slim chance you'll see a major "fireball event" pummel the landscape, or a nearby star explode in what's known as a supernova.
And unless you go out of your way, you may not even see a total solar eclipse, or a blue moon that really is blue.
For sky gazers, time and space often just don't cooperate.
Like when Halley's last was in Earth's neighborhood in 1985-86 for the first time in 76 years: It wasn't a particularly close brush with Earth, and some found the show disappointing.
"I would say that it was a good comet, but it couldn't live up to the 76 years of expectations that the previous generation laid upon us," says W. Scott Kardel, public affairs coordinator for the Palomar Observatory, located in Southern California and operated by the California Institute of Technology.
In fact, Halley's best near-Earth pass may have been in the year 837, when Yeomans says Chinese accounts had it "stretch[ing] from one horizon to the other because it was so close."
"Most famously, it was seen in 1066 before the Battle of Hastings and it was depicted on the Bayeux Tapestry," Kardel says of the comet, once considered a portent of doom.
1910 also was a vintage year. As Halley's made its approach, poisonous gas mistakenly was detected in its tail.
"Cyanogen is a very deadly poison, a grain of its potassium salt touched to the tongue being sufficient to cause instant death," The New York Times reported on Feb. 8, 1910. If Earth were to pass through Halley's tail, an astronomer predicted, "the cyanogen gas would impregnate the atmosphere and possibly snuff out all life on the planet."
Other astronomers dismissed the doomsday theory. Sure enough, our ancestors survived a trip through Halley's tail on July 18, 1910 — regardless of The Times' account of a baseball game played that day: "Comet day was observed at American League Park yesterday with appropriate astronomical fireworks, the Yankees gushing forth a shower of meteorites in the seventh and eighth innings which put the St. Louis Browns groggy under the strong influence of cyanogen gas."
Halley's is expected to pass a bit closer to Earth in 2061, and even closer 76 years later. Don't worry about the cyanogen gas on that spectacular pass, though. We'll all be long dead anyway.