00:00On the night of September 18th, a mountain of rock taller than a skyscraper and older than Earth itself will slip past our planet at more than 24,000 miles per hour.
00:10To the naked eye, the sky will look quiet, but behind that calm is a story six decades in the making.
00:16It makes that closest approach 2025, for 22 will sweep across the Northern Hemisphere, passing above parts of North America.
00:24Europe, North Africa, and Western Asia in the late hours of September 18th and the early morning of September 19th.
00:32Observers in the United States, Canada, the United Kingdom, France, Germany, Italy, Spain, and much of the Middle East will have the clearest.
00:42Window to track it while Southern Hemisphere watchers from Australia to South Africa will need a professional.
00:48Great telescope and perfect skies.
00:51But don't expect a naked eye spectacle.
00:53At its brightest, the asteroid will reach magnitude 13, far dimmer than the faintest stars visible without equipment.
01:01Only a good amateur telescope or a live broadcast, like the Virtual Telescope Project Stream, will reveal its silent flight.
01:08Back in the 1960s, early orbital calculations gave this object a name.
01:13And a warning.
01:142025 F.A.2
01:16A half-kilometer asteroid, with a slim but unsettling chance of striking Earth, in the year 2089, even a rock only 150 meters wide, carries the explosive force of dozens of nuclear weapons.
01:31Imagine the devastation of an impact anywhere on the planet a pressure wave flattening cities.
01:36Global dust clouds chilling the climate.
01:38That remote possibility set astronomers on a long pursuit to know exactly where this traveler was headed.
01:44Observatories across the world joined the effort.
01:47Pan-stars in Hawaii scanned the dark skies night after night.
01:52Radar beams from Puerto Rico's great.
01:55Arecibo, Dishby, for its collapse bounced off the speeding rock to refine its orbit to within kilometers.
02:01Each new measurement cut the risk a little more, until the chance of impact finally shrank to zero.
02:08What once looked like a bullseye is now a clean miss by over 800,000 kilometers, roughly twice the distance from Earth to the moon.
02:17F.A.2-2 belongs to the Apollo class of near-Earth asteroids, bodies, whose orbits regularly cross our own.
02:24Scientists estimate we have discovered barely 60% of asteroids larger than 140 meters.
02:30That leaves thousands still invisible to our surveys.
02:33Every close flyby is more than a spectacle.
02:36It is a rehearsal for the day when one of these ancient fragments is not so forgiving.
02:41F.A.2-2 itself hides details few people know.
02:44It rotates once every 2.7 hours.
02:47A dizzying spin that would challenge any spacecraft trying to land or divert it.
02:51Spectral analysis shows it is a carbonaceous chondry to dark.
02:55It's primitive rock containing water-bearing minerals and organic molecules.
02:58These are the same materials that once rained onto a young Earth, and may have seeded the ingredients of life.
03:05To watch it glide across a telescope S field is to witness a relic from the solar system S birth 4.5 billion years ago.
03:13Tonight, it is only a visitor, but the universe keeps throwing stones.
03:16The more precisely we measure, the better we understand our fragile place in the vast dark.
03:23Knowledge is the shield that stands between cosmic calm and catastrophe.
03:27If you found this story as fascinating as the sky itself,
03:31give this video a like and subscribe to the channel for more journeys into the wonders and warnings of our universe.
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