In the timeframe of the geologically recent history of the Earth, say, 100 million years, several large meteorites have hit Earth. The Cretaceous-Tertiary asteroid, for example, is theorized to have caused the extinction of the dinosaurs. If such an object struck Earth it could have a serious impact on civilization. It is even possible that humanity would be completely destroyed; for this, the asteroid would need to be at least 1 km (0.62 miles) in diameter, but probably between 3–10 km (2–6 miles). Asteroids with a 1 km diameter impact the Earth every 500,000 years on average. Larger asteroids are less common. The last large (>10 km) impact happened 65 million years ago.

Researchers at NASA/JPL, Caltech, and Arecibo Observatory are currently tracking a potentially hazardous asteroid called 99942 Apophis.  The 690-1080 foot diameter object was first discovered in 2004, and was estimated to have an historic chance of impacting Earth on Friday, April 13 of 2029, and again in 2036. Research is continuing on the impact probability, while gathering and analyzing new measurements and the multitude of unmodeled forces acting upon it, that could affect the current trajectory of Apophis. Russia's Space Agency has officially announced it is taking this very seriously, as their scientists "step-up to save the world", by attempting to avert Earth's potential devastation from Apophis. 

So-called Near-Earth asteroids are regularly being observed, including the 7 meter sized, 2009 VA that was only discovered about 15 hours before its very close encounter with earth on November 6, 2009. The object would miss our planet by a mere 8,700 miles.

Terrifying? Hardly. Although the asteroid, identified as 2009 VA, would be the third-closest known (non-impacting) asteroid ever, it was also just 23 feet across. Similar sized objects pass this close to Earth about twice a year and impact the planet about once every five years.

The NASA Near Earth Object (NEO) program aims to detect and track at least 90 per cent of the 1,000 asteroids and comets that approach Earth and are larger than 0.6 miles in diameter, by 2020.  They monitored a 100ft asteroid that whizzed 45,000 miles above the Earth's surface on March 2, 2009. A similar sized object slammed into Tunguska, Siberia in 1908. The impact created a blast so powerful it leveled 1,200 square miles of forest.

However, the government is doing little to find, or stop these killer asteroids.  A White House Advisor has said: The US must prepare for an asteroid strike.  Read this article.

A star passage that will cause an increase of meteorites is the arrival of a star called Gliese 710. This star is moving on a near collision course with the Solar System and will likely pass within 1.1 light years from the Sun in 1.4 million years. Some models predict that this will send large amounts of comets from the Oort cloud to the Earth. Other models, such as the one by García-Sánchez, predict an increase of only 5%.

A number of other scenarios have been suggested. Massive objects, e.g., a star, large planet or black hole, could be catastrophic if a close encounter occurred in the solar system. (Gravity from the wandering objects might disrupt orbits and/or fling bodies into other objects, thus resulting in meteorite impacts or climate change. Also, heat from the wandering objects might cause extinctions; tidal forces could cause erosion along our coastlines.) Another threat might come from gamma ray bursts.

In April 2008, it was announced that two simulations of long-term planetary movement, one at Paris Observatory and the other at University of California, Santa Cruz indicate a 1% chance that Mercury's orbit could be made unstable by Jupiter's gravitational pull sometime during the lifespan of the sun. Were this to happen, the simulations suggest a collision with Earth could be one of four possible outcomes (the others being colliding with the Sun, colliding with Venus, or being ejected from the solar system altogether). If this were to happen, all life on Earth would be obliterated and the impact may displace enough matter into orbit to form another moon. Note that an asteroid just 15 km wide is said to have destroyed the dinosaurs; Mercury is some 5,000 km in diameter.

To help resist this form of catastrophe, the Vivos shelters are designed to withstand:

• The effects of a magnetic pole shift
• Flooding submersion for extended time
• Extreme external fires at 1,250 Fahrenheit
• 450 MPH surface winds
• Force 10 earthquakes in successions
• 100 LB hail stones at speeds of 100 mph