00:00That tiny dot in the sky is an asteroid called 2024 YR4, and it gave scientists a serious scare.
00:11Early projections showed a 2.3% chance that it could hit Earth.
00:16That might sound small, but for an object big enough to wipe out a city, it was enough to raise alarms.
00:23Now, there's good news and bad news.
00:26The good. It's no longer on a collision course with our planet.
00:30The bad. It might be heading for the moon instead.
00:34Astronomers first spotted it in the Alsos Observatory in Chile back in December 2024.
00:41Judging by how bright it appeared, they estimated its size to be somewhere between 130 and 300 feet wide.
00:49That's about the size of a football field.
00:52If something this big hit Earth, it could be truly catastrophic.
00:56I mean, not on the level of the asteroid that wiped out the dinosaurs, but still enough to destroy an entire city, depending on where it lands.
01:05Drop it over Paris, London, or New York, and you're looking at complete devastation across the city and nearby areas.
01:12That's why it was considered one of the most dangerous space rocks to ever come near us.
01:18It makes total sense that this asteroid became a bit of a celebrity.
01:23From the moment it was discovered up until February 2025, the risk of a collision just kept climbing.
01:28But now, we can breathe a little easier.
01:32New calculations from NASA have completely ruled out any chance of impact.
01:36In fact, there's no serious threat from this asteroid for at least the next 100 years.
01:41Okay, but how did we go from this is a threat to, oops, we were wrong?
01:47That happens quite often, actually.
01:49I mean, an asteroid seems risky at first, then it gets even riskier, and then, out of nowhere, it's suddenly safe.
01:56Does that mean we can't trust their math?
01:59You see, the first time specialists spot an asteroid, it's really just a tiny dot of light in the sky.
02:07At that point, they have no idea what it is or where it's headed.
02:12Then, they have to observe it again and do some math.
02:15That will help them figure out the path they're moving on.
02:18But even then, it's still a bit uncertain.
02:21They don't really know where the asteroid is going, so the risk corridor is this huge area where it could fly through.
02:27If any part of that corridor crosses Earth, the asteroid is considered a threat.
02:34Usually, at least three observations are needed to figure out its orbit.
02:38Basically, how fast it's moving and where it's headed.
02:41A lot of times, as they start to get a clearer picture, the risk zone still overlaps with Earth, so it looks more dangerous at first.
02:49But typically, as they keep tracking it, the risk zone gets smaller and moves away from Earth.
02:54And suddenly, the risk drops.
02:56And they keep narrowing down the uncertainties until they can confidently say,
03:01Relax, y'all. It's not heading for Earth.
03:04And that's exactly what happened to just our famous 2024 YR-4.
03:10So, we can all relax a bit now, right?
03:13Yeah, we know that 2024 YR-4 won't hit us.
03:17But it could end up crashing into the moon instead.
03:20At first, projections said there was a 1.7% chance of that happening in 2032.
03:27But recently, that number has gone up a little to 3.8%.
03:32If it does hit the moon, though, it won't be dangerous for us.
03:37I mean, there won't be any shockwaves felt here on Earth, and the moon isn't going to crack in half.
03:43Experts say nothing really shocking or concerning would happen.
03:47But it would be an awesome opportunity to see a lunar impact.
03:51If we're lucky, we might even catch the exact moment it happens.
03:55And if we miss it, we will still get to observe a brand new crater on our natural satellite.
04:01Such events are pretty common for the moon, since it doesn't have an atmosphere to protect it from incoming debris.
04:08In fact, there are hundreds of detectable impacts each year.
04:13See those bright spots lighting up?
04:15These are real images of asteroids hitting the moon.
04:19But specialists aren't just sitting around and waiting.
04:22They've been keeping an eye on lunar impacts for years.
04:26For example, the European Space Agency has a project called Naliota,
04:30where they use a powerful telescope in Greece to track these impacts.
04:35They've recorded over 100 tiny explosions from space rocks hitting the moon.
04:42They also have the Lumio mission,
04:45which is a small satellite that counts lunar impact flashes on the far side of the moon,
04:50the side we can't see from Earth.
04:52These observations help scientists understand how often the moon gets hit
04:57and how this might affect astronauts and lunar bases.
05:02Now, 2024 YR-4 might be a special case.
05:06That's because most space objects that collide with the moon are really small.
05:11We've never seen a collision with something larger than about 160 feet.
05:17If YR-4 does hit, it could be an amazing sight.
05:22So yeah, scientists are kind of hoping it happens.
05:24But 2024 YR-4 isn't the only asteroid on the radar.
05:30There are actually quite a few others that have been classified as potentially hazardous.
05:36In simple terms, that means this one might cause us some trouble.
05:40You see, there are millions of big space rocks out there in the solar system,
05:46mostly chilling in the asteroid belt between Mars and Jupiter.
05:49But only a few ever get close to Earth, and even fewer actually pose any real risk.
05:55NASA calls asteroids that orbit within 30 million miles of Earth near Earth objects.
06:00And within that group, there's a smaller bunch of really big ones that orbit super close to us.
06:07If one of those were to hit us, it could be a big deal.
06:11There are about 2,500 of those asteroids at least that we know of.
06:17But here's the good news.
06:19Specialists don't expect any of them to hit Earth anytime soon.
06:23A few might come pretty close, though, or already have, like the 2014 TN-17.
06:28An asteroid that's about 540 feet wide.
06:34It got pretty close to us in March 2025, zipping by just 3.2 million miles from Earth.
06:40That's roughly 13 times further than the Moon.
06:43So yeah, not exactly close, right?
06:46But when you think about the vastness of the universe, it's actually kind of near.
06:52In fact, that was the closest this asteroid has come to Earth in nearly 300 years.
06:58Thankfully, nothing happened, and that asteroid has already drifted away from Earth again.
07:03But it's not like you need to lose sleep over asteroids that could hit our planet.
07:07Little asteroids enter Earth's atmosphere every single day.
07:11It's the big ones we worry about, like the ones you see in Hollywood movies, like Armageddon.
07:16But asteroids like that are being constantly monitored.
07:21All the objects we know of today have zero or one chance of impacting Earth.
07:26And if things change, there are a few strategies that could be used to save humanity from an impact.
07:32Take the DART mission, for example, which happened in 2022.
07:36This was NASA's first test of planetary defense.
07:41They successfully managed to deflect an asteroid off its course using a spacecraft.
07:46In this case, the asteroid didn't pose any threat to Earth, but it was the perfect test subject.
07:52There are also more experimental ideas out there.
07:55For example, lasers could vaporize part of an asteroid to create a thrust effect, pushing it off course.
08:01Another idea is the Gravity Tractor, a big spacecraft that slowly tugs the asteroid away using its own gravitational pull.
08:11But all of these are still just ideas for now.
08:15If we can't pull any of those off, authorities would probably still have enough time to evacuate the impact zones.
08:22So yeah, I wouldn't stress too much about an asteroid impact.
08:25That's it for today.
08:30So hey, if you pacified your curiosity, then give the video a like and share it with your friends.
08:35Or if you want more, just click on these videos and stay on the bright side.
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