Here is a concise summary of the provided text:
**Title:** Narrow Escapes from Global Catastrophes
**Summary:**
The text highlights the fragility of human civilization, showcasing various close calls with global catastrophes:
1. **Asteroid/Comet Encounters:**
* A comet's fragments narrowly missed Earth in 1883, potentially saving millions of lives.
* The Tunguska event (1908) demonstrated the destructive power of a relatively small asteroid/comet impact.
2. **Nuclear Near-Misses:**
* Multiple incidents during the Cold War, including the Cuban Missile Crisis (1962) and a false alarm in 1983, brought the world to the brink of nuclear war.
* A single safety switch prevented a nuclear explosion in North Carolina (1961).
3. **Solar Storm:**
* A powerful coronal mass ejection (CME) narrowly missed Earth in 2012, which could have caused global power outages and widespread devastation.
4. **Reflection:**
* Despite over 1,000 close calls with nuclear weapons since the 1950s and the threat of natural disasters, human civilization has miraculously persevered.
Here are the key facts extracted from the text, without opinions, and formatted as requested:
1. **Human Migration**: Human ancestors began migrating north from African plains around 60,000 years ago.
2. **José Bonilla's Observation**: On August 12, 1883, Mexican astronomer José Bonilla observed numerous UFOs crossing the Sun, counting 447 objects over two days.
3. **Explanation for Bonilla's Observation**: A 2011 article hypothesized that the objects were fragments of a comet nearly colliding with Earth.
4. **Comet Fragmentation**: The estimated comet broke into over 3,200 fragments, 50-1000 meters in diameter, passing within a few thousand kilometers of Earth.
5. **Tunguska Event**: A powerful explosion occurred in the Siberian taiga around 7:00 AM, flattening approximately 2000 km² of forest (around 80 million trees).
6. **Cause of Tunguska Event**: The broad consensus is that an asteroid or comet (<200 meters wide) exploded a few kilometers above ground, producing a fireball.
7. **Potential Impact on New York City**: If the Tunguska event had occurred over NYC, it could have resulted in approximately 7 million casualties.
8. **US Nuclear Bomber Crash**: On January 24, 1961, a US B-52 bomber carrying two hydrogen bombs crashed in North Carolina.
9. **Near-Nuclear Detonation**: One of the bombs came close to full-scale detonation, with only two wires preventing it; a 3.8 Mt explosion could have affected Washington, Philadelphia, and NYC.
10. **Cuban Missile Crisis**: The crisis in the early 1960s brought the world close to nuclear war, with a Soviet submarine nearly launching a nuclear-armed torpedo at a US destroyer.
11. **Solar Storm Impact**: On May 23, 1967, a powerful solar storm knocked out US military defenses and equipment, initially mistaken for Soviet jamming.
12. **Asteroid Close Call**: On March 22, 1989, a 300-meter-wide asteroid passed close to Earth, missing by only six hours in celestial terms.
13. **Potential Asteroid Impact**: An impact from such an asteroid could obliterate everything within a 60-75 km radius.
14. **Coronal Mass Ejection (CME) Event**: On July 23, 2012, a powerful CME was expelled by the Sun, narrowly missing Earth (by 9 days in celestial rotation).
15. **Potential CME Impact**: If the CME had struck Earth, recovery from widespread electronic failures could have taken up to a decade.
16. **Global Dependency on Technology**: The world's dependency on electricity and technology would lead to global panic and chaos in the event of a catastrophic CME.
17. **US Military Close Calls**: Declassified documents reveal over 1,000 close calls with nuclear weapons since the 1950s, narrowly avoiding cataclysmic devastation.