5 Killer Events From Space That Could Wipe Out Human Life On Earth

The Earth as viewed from a composite of NASA satellite images from space in the early 2000s. While... [+] it may seem like a tall order to end all human life on the planet from an external threat, the Universe is more than up to the challenge.

The 1991 eruption of Mt. Pinatubo was the largest volcanic eruption to occur in our lifetimes. One... [+] that was perhaps 10,000 times the magnitude of this could threaten human life on Earth, and perhaps volcanism was the cause of at least one of our previous major mass extinctions.

A measure of biodiversity, and changes in the number of genera that exist at any given time, to... [+] identify the most major extinction events in the past 500 million years. They are not periodic, and only the most recent one (from 65 million years ago) has a known cause.

A large, rapidly moving mass that strikes the Earth would be certainly capable of causing a mass... [+] extinction event. However, such events appear to be relatively rare. Even though asteroid and comet strikes are frequent, one that causes a mass extinction may be rare enough that no such strikes will occur for billions of years.

The comet that gives rise to the Perseid meteor shower, Comet Swift-Tuttle, was photographed during... [+] its last pass into the inner Solar System in 1992. The influence of the gravity of the other planets has the potential to dramatically change its orbit, however, making it a potential threat to Earth in the year 4479. It has been called the single most dangerous object known to humanity by NASA.

This illustration of the most distant gamma-ray burst ever detected, GRB 090423, is thought to be... [+] typical of most fast gamma-ray bursts. When one or two objects violently form a black hole, such as from a neutron star merger, a brief burst of gamma rays followed by an infrared afterglow (when we're lucky) allows us to learn more about these events. The gamma rays from this event lasted just 10 seconds, but Nial Tanvir and his team found an infrared afterglow using the UKIRT telescope just 20 minutes after the burst.

What we perceive as a gamma ray burst is now known to have at least one identified cause: in merging... [+] neutron stars. If one of the jets from these mergers is pointed at Earth, and is close enough (within about 6,000 light-years), it could destroy the ozone layer, which would lead to humanity's demise.

70,000 years ago, a brown dwarf pair known as Scholz's Star, right on the precipice of igniting... [+] hydrogen fusion in its core, passed through the Solar System's Oort cloud. Stars, failed stars, and stellar remnants pass through our Solar System multiple times every million years.

Over our Solar System’s 4.5 billion year history, the odds that a star would come as close to any of... [+] the planets as our Sun is to Pluto is approximately 1-in-10,000; the odds that a star would come as close to a planet as the Sun is to Earth (which would severely disrupt our orbit and cause Earth's gravitational ejection) is less than 1-in-1,000,000,000. But if it happened, Earth would freeze over in short order, and human life would go extinct.

An optical composite/mosaic of the Crab Nebula as taken with the Hubble Space Telescope. The... [+] different colors correspond to different elements, and reveal the presence of hydrogen, oxygen, silicon and more, all segregated by mass. If the Earth were located within this nebula, which extends about 10 light-years across at present, it could cause an extinction-level event for humanity.

The supernova remnant Cassiopeia A contains signatures of a wide variety of elements of the periodic... [+] table, and would have emitted tremendous amounts of radiation when it first exploded. Type II supernovae are the most common class of supernova, but one would have to occur just a few light-years from us to eliminate our ozone layer, which should be rare enough that the estimated frequency is less than once per few billion years.

The Sun has increased in size, brightness, and temperature according to the curves above, and those... [+] three quantities will continue to evolve as shown by their respective lines into the future. By the time another ~2 billion years pass, its luminosity will be large enough to boil Earth's oceans, effectively ending life on our planet.

Today on Earth, ocean water only boils, typically, when lava or some other superheated material... [+] enters it. But in the far future, the Sun's energy will be enough to do it, and on a global scale.

If all else fails, we can be certain that the evolution of the Sun will be the death of all life on... [+] Earth. Long before we reach the red giant stage, stellar evolution will cause the Sun's luminosity to increase significantly enough to boil Earth's oceans, which will surely eradicate humanity, if not all life on Earth.