Will a Comet or Asteroid Strike the Earth?

Yes: Comets and asteroids have struck the Earth in the past and they will again in the future. Earth has a long and violent history of collisions with extraterrestrial bodies such as asteroids and comet nuclei.

About 1.97 billion years ago, a comet around 6 miles in diameter impacted in Vredefort, South Africa and created the Vredevoort Ring which is 87 miles in diameter.^{1, 21}

About 1.85 billion years ago, a comet impacted the area around Sudbury, Ontario, Canada, producing a crater 125 mile wide.^{21, 23}

End of the Ordovician Period

• There have been five massive extinctions of life on Earth since the earliest fish evolved.¹ The first of these occurred 438 million years ago. Recent evidence is converging on the conclusion that each of these mass extinctions coincided with comet or asteroid impacts.¹⁴

End of the Devonian Period

• A major extinction event occurred 360 million years ago. This was likely caused by an ocean impact since many forms of marine organisms were singled out for extinction.¹

About 300 million years ago, a double impact occurred in Canada forming Clearwater Lakes. The largest crater measured 20 miles across.²³

End of the Permian Period

• A major extinction event (the greatest of them all) occurred 251 million years ago.³³ Ninety percent of all marine species along with seventy percent of all animal and plant life became extinct.³⁵ This extinction resulted from an impact of a comet or asteroid with Earth.³³ The location of the impact is undefined but it may have occurred on the Falkland Plateau at the bottom of the South Atlantic Ocean as evidenced by two large structures, the largest being over 200 miles wide.²¹ Some of the most extensive volcanic activity ever, in what is now Siberia, laid down enough lava to cover the entire planet with ten feet of rock.³⁴

End of the Triassic Period

• About 214 million years ago, 5 large fragments of a comet impacted the Northern Hemisphere. The impacts caused widespread destruction and lead to 3^rd largest mass extinction resulting in the loss of approximately 80% of the species on the face of the planet. The fragments impacted in Quebec, Canada; Saint Martin, Canada; Red Wing, North Dakota; France; and the Ukraine. The largest fragment produced the Manicouagan crater, 62 miles in diameter, in Quebec, Canada.^{1, 2, 22}

About 186 million years ago, a meteorite struck the Vienne Valley in central France producing a crater 14 miles in diameter.

About 140 million years ago, an asteroid impacted in Australia’s Northern Territories producing a ring of mountains 14 miles across.²³

About 73.8 million years ago, a comet or asteroid impacted and created a 22 mile across Manson Structure in Iowa.²²

End of the Cretaceous Period

• About 65 million years ago, an asteroid/comet approximately 10 miles in diameter, impacted the Earth off the coast of Mexico’s Yucatan Peninsula and created a crater 110 miles in diameter. The destruction from this impact caused another mass extinction, the second largest. Over 90% of the species vanished. This extinction brought an end to the age of dinosaurs.^{1, 2, 22, 38}

About 35.5 million years ago, two asteroids/comets collided with the Earth. The first produced a 50-mile diameter crater under the Chesapeake Bay. The second produced a 60-mile diameter crater near Popigai, east of the Ural Mountains in northern Siberia, Russia.²¹

About 15 million years ago, an asteroid/comet approximately 0.9 miles in diameter impacted and formed the Ries Crater approximately 15 miles across in Bavaria.¹⁶

About 2.15 million years ago, an Eltanin asteroid between 0.5 to 2.5 miles in diameter struck the Bellingshausen Sea of Antarctica.^{5, 18} This impact created a devastating tsunamis with waves 65 to 130 feet high. ¹⁸

About 300,000 years ago, an asteroid impacted Earth, creating the Wolfe Creek Crater in Australia, which is 0.5 miles across.²³

About 49,000 years ago, an asteroid approximately 0.03 miles in diameter impacted Earth, creating the Meteor Crater (Barringer Crater) 0.75 miles across in Winslow, Arizona.^{2, 23}

Less than 10,000 years ago, an asteroid impacted west of Ungava Bay in Canada producing a 0.12 mile diameter crater called the Merewether Crater.²³

Less than 10,000 years ago, an asteroid impacted south of the Alice Springs area in Australia, producing 13 impact craters, the Henbury crater cluster, the largest being 0.14 miles across. The aborigines refer to this area as "sun walk fire devil rock".²³

Around the year 535 AD, the Earth was pummeled by a swarm of cosmic debris, which produced two year long winters. Crops failed. Plague and famine decimated Italy, China and the Middle East. A 6^th-Century Syrian bishop, John of Ephesus wrote, "The sun became dark... Each day it shone for about four hours and still this light was only a feeble shadow." This was the beginning of the Dark Ages. Researchers indicate similar environmental calamities occurred about 3200 BC, 2300 BC, 1628 BC and 1159 BC.¹⁴

About 800 years ago, an air burst caused by an asteroid or comet fragment occurred over New Zealand’s South Island.¹⁷

In the year 1490, a wave of meteorites impacted the Earth in Qingyang, Shaanxi, China, with such ferocity that stones were said to have fallen like rain, killing tens of thousands of people.^{4, 18, 23}

On 23 April 1803, a wave of 2,500 meteorite stones fell at L’Aigle, Normandy.²²

On 30 June 1908, a comet fragment approximately 0.05 miles in diameter entered the Earth’s atmosphere and exploded in the air above the Tunguska Valley in Siberia, Russia. The force of the explosion (approximately 10-15 megatons of TNT) knocked down millions of trees within an area of 1000 square miles.¹⁵ This comet fragment was probably a remnant of the comet Encke.¹⁶

On 13 August 1930, an asteroid or comet fragment approximately 0.05 miles in diameter produced an airburst in the Amazonian Rain Forest similar to the Tunguska event resulting in considerable ground damage and depopulating the area.^{16, 22}

In 1947, an asteroid struck Brazil creating several craters.⁴ Another asteroid impact occurred on 12 February 1947 in the Sikhote-Alin region of Siberia in southeastern USSR, forming 122 small craters up to 0.02 miles across.^{13, 23}

Over 150 asteroid/comet impact craters have been identified on the surface of the Earth. An extensive catalogue of impact structures appears in http://www.unb.ca/passc/ImpactDatabase/. Impact of asteroids/comets in the 6-mile diameter range, the size that produces global extinction, occur every 50 to 100 million years.^{2, 41}

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