00:00Hundreds of millions of rocks orbit the Sun within the asteroid belt between Mars and
00:05Jupiter, but only some of them come relatively close to Earth.
00:09NASA classifies asteroids orbiting within 30 million miles of our planet as near-Earth
00:15objects, and inside this group, there are particularly worrisome objects.
00:20Those are so large and orbit so closely to our home planet that they could turn into
00:25a real threat to the world should a direct collision occur.
00:29At the moment, NASA is keeping a close eye on an asteroid named Bennu.
00:33It's a fairly large space object that might smash into our planet in 159 years.
00:40According to the experts, the asteroid, which was first spotted in 1999, is quite likely
00:45to drift into the orbit of our planet.
00:48If it happens, it might collide with Earth by the 24th of September, 2182.
00:56Asteroid Bennu is thought to be taller than the Empire State Building.
00:59If that hits our planet, the collision will release 1,200 megatons of energy.
01:05That's an enormous amount of energy that nothing built on Earth could produce.
01:10Scientists from NASA believe that during the flyby in the 22nd century, there's a tiny
01:15chance that the asteroid will pass through a gravitational keyhole.
01:18That's a region of space that might set the space traveler on a certain path, which
01:23could result in the asteroid crashing into Earth.
01:27Bennu flies by our planet every 6 years.
01:30It has had 3 close encounters with Earth – in 1999, 2005, and 2011.
01:36These days, scientists estimate the chance of the asteroid hitting our planet by 2182
01:42as 1 in 2,700.
01:44That's more than 5 times a person's chance of being struck by lightning.
01:50Even though Bennu's chances of colliding with Earth are quite low at the moment, the
01:54space rock has still been categorized as a quote, potentially hazardous asteroid.
02:00All because it might come as close as 4.65 million miles from Earth.
02:05That's the reason why it's also classified as a near-Earth object.
02:10Bennu is a carbon-rich asteroid that was formed in the first 10 million years of the history
02:15of the Solar System.
02:17That's around 4.5 billion years ago.
02:20No wonder this space body holds precious clues to the origin and development of the rocky
02:25planets of our Solar System, which are, as you recall, Mercury, Venus, Earth, and Mars.
02:31Even better, it may contain organic molecules similar to those that are crucial for life
02:36to evolve.
02:37In 2020, NASA's OSIRIS-REx managed to briefly touch the surface of the asteroid.
02:43They collected some samples and propelled off the space rock afterward.
02:47For NASA, it was the first mission of this kind.
02:52But it won't probably come as a surprise that Bennu isn't the only asteroid we should
02:56worry about.
02:58Asteroid 99942, Apophis, is another space body we'd better watch out for.
03:04It's a near-Earth object about 1,100 feet across.
03:08It was discovered in 2004, and at first, it was identified as one of the most dangerous
03:13asteroids ever detected.
03:16Apophis gained notoriety very fast.
03:19It was believed to pose a serious threat to Earth.
03:22Experts predicted that it would come uncomfortably close to our planet in 2029.
03:27Luckily, after a more careful examination of Apophis and its orbit, astronomers concluded
03:33that there was no risk of the asteroid colliding with our planet for at least a century.
03:39The risk of an impact in 2029 was ruled out completely, as well as the potential impact
03:44that could be caused by the asteroid's close approach in 2036.
03:49Interestingly, until March 2021, there was a small chance of a collision in 2068.
03:57But then Apophis made a flyby of Earth, and astronomers took this chance to use powerful
04:02radars to estimate the asteroid's orbit around the Sun more precisely.
04:07This allowed them to rule out any impact risk for at least the next 100 years.
04:13The reason why such discoveries make us so worried is that even a relatively small asteroid
04:19– the size of a house – can wreak havoc upon colliding with our planet.
04:24And if an asteroid is larger than 0.6 miles across, astronomers call it a planet destroyer.
04:31The impact energy released by such an asteroid after striking Earth could be devastating.
04:35That's why knowing where such asteroids are and in what direction they're moving
04:40is crucial.
04:42The problem is that our capability to protect the planet from asteroid impacts is not top-notch
04:48yet.
04:49If such a catastrophe was about to occur, we would need some time to prepare because
04:53an asteroid collision is no joke.
04:56Probably the most well-known asteroid impact site is the Chicxulub Crater.
05:01It's the evidence of the terrifying collision that led to the extinction of dinosaurs.
05:06Strangely, this crater isn't very visible.
05:09But some others are.
05:10For example, Beringer Crater in Arizona, which is also called Meteor Crater.
05:15It looks rather blood-chilling when you think about the collision that led to its appearance.
05:22In any case, we now know that space rocks hit not only the Earth but also the Moon,
05:27Mercury, and Mars.
05:29No rocky planet in the Solar System is safe from asteroid impacts.
05:33That's why we have an entire scientific enterprise whose goal is to find and catalog
05:38the asteroid population of the Solar System.
05:42It might sound a bit scary, but there are around 25,000 asteroids larger than 460 feet
05:48in diameter near the orbit of our planet.
05:52Such a space rock is large enough to wipe an entire city off the face of the Earth.
05:57So far, less than 50% of such asteroids have been detected and tracked.
06:02There are also an estimated 230,000 objects equal to or larger than 160 feet in size.
06:10Those are capable of destroying a concentrated urban area.
06:13And still, fewer than 8% of those have been detected.
06:17There are also tens of millions of smaller near-Earth objects.
06:21They are larger than 33 feet across and might cause some surface damage.
06:26Less than 1% of such small space bodies have been discovered so far.
06:32Now the thing is, the inner Solar System is extremely challenging for asteroid search.
06:38Each night, there are only two 10-minute windows when astronomers can observe the region.
06:43All because the sun's glare creates a very bright background glow.
06:47Plus, the atmosphere of our planet also distorts and blurs observations.
06:52Spotting asteroids in such conditions is beyond the capabilities of most telescopes.
06:57A unique instrument is needed to fulfill this task.
07:01And the tool of choice is the Dark Energy Camera at Cerro Tololo Inter-American Observatory
07:07in Chile.
07:08This device wasn't designed to hunt asteroids.
07:11Astronomers built it to search for another elusive target, dark energy, the mysterious
07:15force driving the expansion of the Universe.
07:19The DEC is supposed to observe hundreds of millions of galaxies.
07:23That's why it's both wide and deep.
07:26This way, it can both peer deep into the Universe and capture a wide field of view, which helps
07:31it record the motions of galaxies and the conditions in the early age of the Universe.
07:38But it also means that the DEC is perfectly suited to spotting asteroids near the sun.
07:44Inner asteroids are rare, and deep images are necessary because such asteroids are faint.
07:50Scientists need to be able to fight both the bright twilight sky near our star and the
07:54distorting effect of Earth's atmosphere, and the DEC can help them achieve their goal.
08:00The Dark Energy Camera was built to carry out the Dark Energy Survey, which finished
08:05in 2019.
08:07Now astronomers can direct the power of the camera towards other tasks.
08:11They claim that the DEC's survey is one of the most sensitive searches ever performed
08:16for objects near Venus' orbit and within the orbit of our planet.
08:20It provides us a great chance to find out what kinds of objects are lurking in the inner
08:25solar system.
08:28That's it for today, so hey, if you pacified your curiosity, then give the video a like
08:37and share it with your friends.
08:38Or if you want more, just click on these videos and stay on the Bright Side!
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