An asteroid on a trajectory to impact Earth could not be shot down in the last few minutes or even hours before impact. No known weapon system could stop the mass because of the velocity at which it travels – an average of 12 miles per second.
Kinetic impactor
Kinetic impactors are one way by which we might be able to alter an asteroid's path. In principle, this technique requires smacking an asteroid to change its orbit around the sun so it no longer is a threat to Earth.
Their experiments showed that blowing up a 200-meter asteroid would require a bomb 200 times as powerful as the one that exploded over Hiroshima in 1945. They also said it would be most effective to drill into the asteroid, bury the bomb, then blow it up—just like in the movie Armageddon.
Technically, a nuclear bomb could obliterate a smaller asteroid, but it's not these smaller entities that pose a threat to Earth's safety. The asteroids that would be really worrisome -- those larger than 1,312 feet (400 meters) -- wouldn't be easily wiped out by such a bomb.
Designated 2023 BU, the asteroid will zoom over the southern tip of South America at about 4:27 p.m. PST (7:27 p.m. EST) only 2,200 miles (3,600 kilometers) above the planet's surface and well within the orbit of geosynchronous satellites. There is no risk of the asteroid impacting Earth.
An asteroid, named "2019 PDC", was discovered that will come dangerously close to the earth 8 years from now, on April 29, 2027. The space rock is between 330 and 1000 feet in size, somewhere in between the length of 6.5 school buses to the height of two Washington Monuments stacked on top of each other.
Scientists have predicted that Earth will get warmer by the year 2027 compared to the 19th century and this may change the weather conditions of the world.
This could be done by impacting it with a non-destructive projectile, simply tugging the asteroid into a different orbit with a nearby high-mass spacecraft, ablating the asteroid's surface with a high-power laser (or a nearby nuclear explosion), or by placing small rockets on the asteroid's surface.
You'd need the power of 4,000 of those to annihilate a 20-kilometer-wide asteroid. But even then, you couldn't just launch 4,000 nuclear weapons to destroy the asteroid. That energy would need to be delivered with a particular momentum (that is, motion confined to a particular mass).
When the 6-mile-wide asteroid that led to dinosaur extinction hit Earth 66 million years ago, the impact also triggered a “mega-earthquake” that lasted weeks to months, new evidence suggests.
There are a variety of deflection techniques that could save Earth from an incoming asteroid. They range from using a large spacecraft's gravity to pull the asteroid off course, to sending up a kinetic impactor to slam into the asteroid, or even using nuclear detonations.
If a nuclear weapon is exploded in a vacuum-i. e., in space-the complexion of weapon effects changes drastically: First, in the absence of an atmosphere, blast disappears completely. Second, thermal radiation, as usually defined, also disappears.
Once a nuclear missile has been launched, there is very limited capabilities of stopping that missile. No nation has a credible system in place to combat launched nuclear weapons. However, there are steps we can take to prevent a nuclear missile from being launched.
In fact, currently, there are no large asteroids predicted to hit Earth for the next 100 years. The object with the highest probability of colliding with Earth was the 1,100 feet (340 m) wide asteroid 99942 Apophis, which was predicted to get dangerously close to Earth in 2068.
The largest asteroid to ever hit earth was an asteroid named Vredefort. This absolutely gargantuan asteroid was likely around 12.4 and 15.5 miles across and was traveling between 45,000 and 56,000 mph when it hit the surface.
The planet Earth has been around for more than 4.5 billion years. And in the course of its history it has been hit by asteroids at least 190 times. But there were three particular occasions when the asteroid was so large and the impact crater it created was so wide, scientists are sure it would have ended humanity!
A declassified document shared by nuclear historian Alex Wellerstein gives the verdict that scientists at the Los Alamos laboratory and test site reached in 1945. They found that "it would require only in the neighborhood of 10 to 100 Supers of this type" to put the human race in peril.
Abstract. 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. The exact reason for such a result remains nevertheless uncertain.
It would take just three nuclear warheads to destroy one of the 4,500 cities on Earth, meaning 13,500 bombs in total, which would leave 1,500 left. 15,000 warheads are the equivalent of 3 billions tons of TNT and 15x the energy of the Krakatoa volcano, the most powerful volcanic eruption ever.
NASA scientists say it would take an asteroid 60 miles (96 kilometers) wide to totally wipe out life on Earth. Asteroid Didymos (bottom left) and its moonlet, Dimorphos are seen less than three minutes before NASA's DART spacecraft made impact. This is the last image to include a complete view of both asteroids.
With an asteroid hitting the Earth; dust and smoke rising in the atmosphere prevents sunlight from reaching our world and causes the total temperature to drop. This event can lead to the death of many living things. If an asteroid the size of an apartment hits Earth, this blow could possibly destroy a small city.
Because both the needed velocity change and the mass of Apophis are small, the needed impulse (change in momentum) is so small that deflection can be done simply by ramming the asteroid with the spacecraft, and such a deflection by impact is the easiest deflection method.
By 2050, due to the lack of greenery, concrete forests will be made in its place. At this time there will be such a shortage of land that many big buildings will be cultivated to meet the needs of food and drink. According to a US report, the sea level will increase by 2050.
The earth would become warmer, the average temperature will increase. There will be several new weather patterns and the sea levels would rise. Eventually humans would die out. If the insect population continues to decline, all birds that depend on insect for food will become extinct.
Besides drought and sea level rise, there are a variety of other likely changes around the world. There might be intense heat waves, increased incidences of infectious and respiratory diseases, changes in ecosystems particularly at high latitudes, and loss of biodiversity ... just to name a few.