Things to Worry About
- On April 13, 2036, the asteroid 99942 Apophis will strike the
earth with a probability of about 1:5900. Apophis, which is about
320 m in diameter and has an approximate mass of 4.6×1010
kg, would have the effect of a 880 megaton explosion if it hit;
for comparison, Krakotoa was about 200 megatons.
- On May 28, 2057, the asteroid 2005 WY55 will strike the earth
with a probability of about 1:8200. The diameter of 2005 WY55 is
estimated at between 210 and 480 meters.
- On May 4, 2102, the asteroid 2004 VD17 will strike the earth
with a probability of about 1:1600. 2004 VD17 is about 580 m in
diameter, with a mass estimated at 2.7×1011 kg. An
impact would have an estimated effect of 15,000 megatons.
- On March 16, 2880, the asteroid 1950 DA will strike the earth
with a probability of at most 1:300. The size and mass of 1950 DA
are poorly known, but since it is over 1 km in diameter an impact
would be expected to cause global devastation.
- A "supervolcano" eruption, which would dramatically cool global climate
for several years, could occur at any time. The last such eruption may have
occured 74,000 years ago, when the Toba eruption (in what is now Indonesia)
cooled temperatures in the Northern Hemisphere so much that it has been
estimated that three-fourths of plants there died. One past and probable
future supervolcano is Yellowstone, which last erupted on this scale
640,000 years ago; if repeated today, it would cover half the United States
with 3 meters of ash.