To destroy all life, an asteroid would need to be enormous, potentially tens to hundreds of kilometers wide, causing catastrophic, planet-wide environmental collapse with dust clouds blocking the sun, triggering mass extinctions. While a 10-kilometer (6-mile) asteroid (like the Chicxulub impactor) causes mass extinctions and ends civilizations, an even larger object, perhaps 60 kilometers (37 miles) or more, might be needed for total global sterilization, depending on factors like composition and speed, though the 10 km event is already civilization-ending.
The risk of humanity extinction by giant asteroid impact is addressed. A 100 km sized asteroid impact may transform the Earth into an inhospitable planet, thus causing the extinction of many life forms including the human species.
We now know that quite large objects - 40m across or more - pass between Earth and the Moon several times a year. That's the same size of asteroid that exploded over Siberia in 1908 injuring people and damaging buildings over 200 square miles.
If you think a 1000-mile-wide asteroid hit would make the Atlantic Ocean very hot or cause a tsunami, you must understand it's another category of event. All water on Earth would likely evaporate, and the Earth's crust would turn into molten rock.
An asteroid about 300 feet (90 meters) in size, which is much less likely, could cause more severe damage, potentially collapsing residential structures across a city and shattering windows across larger regions.
If the asteroid was as big as a 20-story building (200 feet [61 meters] on a side), it could have the amount of energy equal to the largest nuclear bombs made today — about 25 to 50 megatons. This size asteroid would flatten reinforced concrete buildings 5 miles (8 kilometers) from ground zero.
A 300m-wide asteroid will not hit the Earth in 2036, US astronomers say. It was thought there was a one-in-200,000 chance that it could strike on 13 April 2036, but revised calculations have now ruled this out. Instead, Nasa scientists said it would not get closer than 31,000km as it flies past on this date.
Any asteroid that's over 1 kilometer in size is considered a planet killer — and one day, one of them might head our way. An impact event of this size would trigger an extinction event like Earth has never seen.
On April 13, 2029, the large asteroid Apophis (99942) will have a very close, but safe flyby of Earth, passing within 32,000 kilometers (20,000 miles) of our planet—closer than some satellites—and will be visible to the naked eye in the night sky from parts of the Eastern Hemisphere (Europe, Africa, Asia) as a bright, fast-moving point of light. This rare event offers scientists a unique opportunity to study an asteroid of its size (about 375 meters wide) up close, with missions like NASA's OSIRIS-APEX and ESA's Ramses planned to observe it.
ASTEROID'S CHANCE OF EARTH IMPACT IN 2027 NOW 96%
Based on new tracking measurements taken this week, the International Asteroid Warning Network (IAWN) has confirmed that asteroid 2017 PDC is on a course that will almost certainly impact Earth on July 21, 2027, less than nine years from now.
The explosion took place over the snow covered city of Chelyabinsk in Russia, near the border with Kazakhstan. The impact of this meteorite caused destruction around the city. The shock wave was powerful enough to injure around 1,500 people. It shattered more than 3,600 windows in apartments and commercial buildings.
The asteroid is thought to have been between 10 and 15 kilometres wide, but the velocity of its collision caused the creation of a much larger crater, 150 kilometres in diameter.
As of late 2022, the most likely and most effective method for asteroid deflection does not involve nuclear technology. Instead, it involves a kinetic impactor designed to redirect the asteroid, which showed promise in the NASA DART mission.
The asteroid that led to the extinction of the dinosaurs as well as 70% of all species on Earth was at least 10 to 15 kilometers wide. It was much larger than Apophis, though millions of people could still die if an Apophis-sized asteroid struck a major metropolitan area. How close will Apophis come to Earth in 2029?
The largest yield of a thermonuclear warhead is around 50--100 megatons. The kinetic energy of the falling object is converted to the explosion when it hits. The 10-kilometer object produces an explosion of 6 × 107 megatons of TNT (equivalent to an earthquake of magnitude 12.4 on the Richter scale).
The warning time could indeed be very short, five years, and the kinetic energy could be sufficient for global and durable effects on Earth, killing all life forms on the surface. Humans might nevertheless be able to survive decades in underground shelters.
Observations eliminated the possibility of an impact on Earth in 2029, when it will pass the Earth at a distance of about 38,000 kilometres (23,600 mi) above the surface. It will also have a close encounter with the Moon, passing about 96,000 km from the lunar surface.
Astronomers closely tracked the asteroid, and now NASA is confident that there is no risk of Apophis impacting our planet for at least 100 years.
Impacts of projectiles as large as one km in diameter are generally thought to explode before reaching the sea floor, but it is unknown what would happen if a much larger impactor struck the deep ocean. The lack of a crater, however, does not mean that an ocean impact would not have dangerous implications for humanity.
Known as 16 Psyche, this massive space rock is estimated to be worth a staggering $700 quintillion. To put that into perspective, that amount of wealth would be enough to make every single person on Earth a billionaire. What makes this asteroid so extraordinary is its composition.
Still larger asteroids are much more dangerous, and the graph (left) shows how the explosion from the impact of a 100-meter (330-feet) diameter asteroid and larger could kill a million people, averaged over all possible impact locations.
On April 13, 2029 (which happens to be Friday the 13th), something unsettling will happen. A decent-sized asteroid, the 1,100-foot-wide Apophis, will pass so close to Earth it'll be visible in the sky from certain places. Crucially, the giant rock will not strike our humble planet.
# 1: Coronal Mass Ejections
Yes, this can happen to humanity on Earth… it has happened before! The very source of life for humanity is, indeed, our greatest threat.
Given enough warning, yes we could deflect it. As far as how much warning we would get is variable depending on if the asteroid approaches from the sunward side of earth's orbit or from the night side. But an asteroid that size would likely get detected years in advance.