Improve this question. B--rian 5, 2 2 gold badges 12 12 silver badges 57 57 bronze badges. If it's a near-Earth asteroid we might know it for years before a possible Earth impact. Apophis is much smaller and was thought to possibly impact the Earth in , and it's being tracked since beginning of this century. I thought we already had technology to detect things like massive asteroids in like a century but appearently not all of them. Why is this not considered a big problem for humanity?
But all the currently discovered asteroids and comets don't seem to pose any threat to Earth anyway in the following decades.
Methods to redirect or break up asteroids are being worked on. Recent missions to asteroids are, in part, to learn more about their composition and practice techniques for tracking and altering their orbit. And Elon Musk is working on his lifeboat. Show 3 more comments. Active Oldest Votes. Notes: The above outlined scenario is almost impossibly unlikely.
Improve this answer. I ran the equations back through with this correction and reduced albedo from 0. My post is edited above. I am sorry. If we get a big, dense, asteroid with low albedo coming into our solar system with escape velocity in an earth impact trajectory, it isn't good for the fate of life on this planet. And we won't have much notice. This places it 0. This makes it more than 25 times brighter and it can therefore be seen at least 5 times further away.
Weeks, not hours. You are also right about my density being a bit too high and asteroid brightness not varying quite as the inverse square of distance, but I don't think either affects my answer too much. I think I'm right about the asteroid size. Crater size is good for approximating kinetic energy, but it isn't good for approximating asteroid size. For a worst case scenario, we should approximate our own size for a dense, fast, mover.
Show 2 more comments. So we are pretty sure that there are no asteroids of that size that will hit us. James K James K Same can be true for asteroids. While the probability is low, it's something that can't be ruled out based on what we know now because it involves a change.
Let's hope that space is really really big and the probability is very very remote. I do remember there were many enjoyable books, one time a purse was forgotten, one trime one wasn't - fact?
Everytime I try to remember anything about this topic I start hearing banjos - fact! Add a comment. The comet is 3. Earth is 0. In reality, if an asteroid like that fictional one were heading for Earth, scientists would need years — not months — of warning.
Five years is the minimum, according to Chodas. But scientists haven't identified most of the hazardous space rocks that pass near our planet, which makes the chances slim that we'd get a five- or year warning period. At that size, asteroids could obliterate a city the size of New York. In NASA's recent simulation, the participating scientists didn't know how big the hypothetical asteroid was until a week before it was set to hit Earth. And that makes a very big difference," Sarah Sonnett, a researcher at the Planetary Science Institute who participated in the exercise, told Insider.
A meter asteroid could explode in the atmosphere and send shockwaves through a neighborhood. A meter asteroid could decimate a city, affecting an area the size of France.
So a crucial part of stopping an asteroid from hitting Earth is understanding as much as possible about the rock. That includes its size, the path it takes around the sun, and what it's made of. With that information, scientists can evaluate strategies to dismantle the rock or disrupt its path. Ideally, Sonnett said, scientists would be able to study a hazardous asteroid as it passed Earth a few times in its orbit around the sun, before that path brought it close enough to collide with our planet.
Observing a passing asteroid several times could take years or even decades. NASA has three main tools in its planetary-defense arsenal. The first is to detonate an explosive device near an oncoming asteroid to break it up into smaller, less dangerous chunks.
The second is to fire lasers that could heat up and vaporize the space rock enough to change its orbital path. The third is to send a spacecraft to slam into the asteroid, knocking it off its trajectory. NASA is about to test that last strategy.
But the world's ability to surveil near-Earth objects is woefully incomplete. Any space rock with an orbit that takes it within million miles of the sun is considered an NEO. But Johnson said in July that NASA thinks "we've only found about a third of the population of asteroids that are out there that could represent an impact hazard to the Earth.
Of course, humanity hopes to avoid a surprise like the dinosaurs got 65 million years ago, when a 6-mile-wide asteroid crashed into the Earth. But in recent years, scientists have missed plenty of large, dangerous objects that came close. Comet Neowise, a 3-mile-wide chunk of space ice, passed within 64 million miles of Earth in July.
Nobody knew that comet existed until a NASA space telescope discovered it approaching four months prior. In , a meteor about 65 feet in diameter entered the atmosphere traveling 40, mph. It exploded over Chelyabinsk, Russia, without warning, sending out a shock wave that broke windows and damaged buildings across the region.
More than 1, people were injured. And in , a foot-wide "city-killer" asteroid flew within 45, miles of Earth. NASA had almost no warning.
That's because the only way scientists can track an NEO is by pointing one of Earth's limited number of powerful telescopes in the right direction at the right time. To address that problem, NASA announced two years ago that it would create a space telescope dedicated to watching for hazardous asteroids.
NASA has investigated the options scientists would have if they were to find a dangerous asteroid on a collision course with Earth. These include detonating an explosive device near the space rock, as the exercise participants suggested, or firing lasers that could heat up and vaporize the asteroid enough to change its path.
Another possibility is sending a spacecraft up to slam into an oncoming asteroid, knocking it off its trajectory. This is the strategy NASA is most serious about: Later this year, the agency is scheduled to launch a test of such a technology.
The Double Asteroid Redirection Test will send a spacecraft to the asteroid Dimorphos and purposefully hit it in the fall of NASA hopes that collision will change Dimorphos' orbit.
0コメント