Source: NASA releases new details on ‘city-killer’ asteroid — and the moon may be at risk of being struck
经过两个月的观测，NASA 科学家正式宣布地球不会受到“城市杀手”小行星 2024 YR4 的威胁。 据美联社报道，周二，NASA 最近将太空岩石撞击地球的概率定为 0.0017%，这意味着它几乎肯定会在 2032 年飞越我们的星球，并且不会在下个世纪对我们构成威胁。 NASA 近地天体研究中心负责人保罗·乔达斯在一份声明中表示：“这是我们一直期待的结果，尽管我们不能 100% 确定它会发生。” 这标志着一次重大的路线修正，因为就在一周前，NASA 称，这颗直径在 131 至 295 英尺之间岩石撞击地球的概率为 1.5%。 撞击风险系数在一天前达到最高点，达到 1/32，即 3.1%，这使得 YR4 成为自十多年前 NASA 近地天体研究中心风险追踪表建立以来最危险的小行星。 这一结果与科学家的预测一致，他们预测撞击风险会急剧上升，然后回落至零。 这是幸运的，因为深度撞击将释放出相当于 8 兆吨 TNT 的能量冲击——大约是投在广岛原子弹威力的 500 倍——并可能威胁到数亿人的生命。 虽然地球可能已经脱离危险，但不幸的是，月球仍然可能成为目标。 NASA 警告说，我们的 YR4 撞击我们的天然卫星的概率为 1.7%，这比之前的预测大幅增加。 与地球不同，月球缺乏大气层保护，因此撞击发生的速度将达到每小时 30,000 英里，并留下直径 1,640 至 6,500 英尺的爆炸坑。
After two months of observations, NASA scientists have officially declared Earth safe from “city-killer” asteroid 2024 YR4.
On Tuesday, the space agency recently placed space rock’s impact probability at just 0.0017%, meaning it will almost certainly fly by our planet in 2032 and won’t threaten us in the next century, the AP reported.
“That’s the outcome we expected all along, although we couldn’t be 100% sure that it would happen,” Paul Chodas, the head of NASA’s Center for Near Earth Objects Studies, said in a statement.
This marks a remarkable course correction given that just a week ago, the rock — which measures between 131 and 295 feet in diameter —had a 1.5% chance of hitting Earth, per the space agency.
At its highest point a day earlier, the impact risk factor clocked in at 1 in 32, or 3.1%, making YR4 the most dangerous asteroid since the inception of NASA’s Center for Near Earth Object Studies (CNEOS) Sentry Risk Table over ten years ago.
This outcome is in line with scientist predictions stipulating that the odds would skyrocket before reversing back down to zero.
This is fortunate as a deep impact would release an energy blast equivalent to 8 megatons of TNT — roughly 500 times the power of the atomic bomb dropped on Hiroshima — and could potentially threaten the lives of hundreds of millions of people.
While the Earth might be out of the woods, the moon could still be in the crosshairs, unfortunately.
NASA warned that our YR4 has a 1.7% chance of striking our natural satellite, marking a substantial increase from prior predictions.
Unlike the Earth, the moon lacks an atmosphere to protect it, so the impact would occur around 30,000 miles per hour and leave a blast crater measuring between 1,640 to 6,500 feet across.
