|Meteors: Fire in the Sky
Meteors Likely Carried the Building Blocks for DNA
Elaborate computer graphics and visits to impact sites worldwide
highlight this look at the extra-terrestrial visitors that have helped
shape our planet. Computer simulations reveal what impacts with
earth could be like.
Panspermia is the hypothesis that life exists throughout the Universe, distributed by meteoroids, asteroids and planetoids.
Panspermia proposes that life that can survive the effects of space, such as extremophile bacteria, become trapped in debris that is ejected into space after collisions between planets that harbor life and Small Solar System Bodies.
Bacteria may travel dormant for an extended amount of time before colliding randomly with other planets or intermingling with protoplanetary disks.
If met with ideal conditions on a new planets' surfaces, the bacteria become active and the process of evolution begins.
Panspermia is not meant to address how life began, just the method that may cause its sustenance.
A fascinating look at the vagabonds that
litter the solar system. Hear from experts like David Levy and
Carolyn Shoemaker, discoverers of a comet that collided with Jupiter.
cross the solar system and hold clues about our planet and universe.
Can they destroy civilizations? Did they wipe out the dinosaurs? Have
they brought life to our planet? And when will the next one hit?
by elaborate animation and live-action footage, METEORS explores what
likely happened 65-million years ago, when an object plowed into the
See how certain spectacular meteor falls advanced our
understanding of what they are and the danger that they pose.
leading experts, astronomers and geologists like David Levy and Carolyn
Shoemaker, co-discoverers of a comet that fell into Jupiter in 1994.
talk to NASA scientists possible ways to move Earth-threatening
asteroids and comets out of our way. Because it isn't a question of if
the next deadly impact will take place, but when.
The idea that life on Earth was "seeded" from elsewhere in the universe dates back at least to the fifth century BCE. Allan Hills 84001 is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984 by a team of U.S. meteorite hunters from the ANSMET project.
On discovery, its mass was 1.93 kilograms (4.3 lb) and many believe this meteorite came from Mars. It made its way into headlines worldwide in 1996 when scientists announced that it might contain evidence for microscopic fossils of Martian bacteria based on carbonate globules observed.
Earth has gone through periods of abrupt and catastrophic change, some due to the impact of large asteroids and comets on the planet. A few of these impacts may have caused massive climate change and the extinction of large numbers of plant and animal species.
The Moon is widely attributed to a huge impact early in Earth's history.
Impact events earlier in the history of Earth have been credited with creative as well as destructive events.
It has been proposed that impacting comets delivered the Earth's water, and some have suggested that the origins of life may have been influenced by impacting objects by bringing organic chemicals or lifeforms to the Earth's surface, a theory known as exogenesis or panspermia.
These modified views of the Earth's history did not emerge until relatively recently, chiefly due to a lack of direct observations and the difficulty in recognizing the signs of an Earth impact because of erosion and weathering.
Large-scale terrestrial impacts of the sort that produced the Barringer Crater, locally known as Meteor Crater, northeast of Flagstaff, Arizona, are rare.
Instead, it was widely thought that cratering was the result of volcanism: the Barringer Crater, for example, was ascribed to a prehistoric volcanic explosion (not an unreasonable hypothesis, given that the volcanic San Francisco Peaks stand only 30 miles (48 km) to the west).
Similarly, the craters on the surface of the Moon were ascribed to volcanism. It was not until 1903–1905 that the Barringer Crater was correctly identified as being an impact crater, and it was not until as recently as 1963 that research by Eugene Merle Shoemaker conclusively proved this hypothesis.
The findings of late 20th-century space exploration and
the work of scientists such as Shoemaker demonstrated that impact
cratering was by far the most widespread geological process at work on
the solar system's solid bodies.
Vredefort crater is the largest verified impact crater on Earth. It is located in the Free State Province of South Africa and named after the town of Vredefort, which is situated near its centre.
Every surveyed solid body in the solar
system was found to be cratered, and there was no reason to believe that
the Earth had somehow escaped bombardment from space.
In the last few decades of the twentieth century, a large number of
highly modified impact craters began to be identified. The largest of
these include Vredefort Crater, Sudbury Crater, Chicxulub Crater, and
The first observation of a major impact event occurred in 1994: the collision of the comet Shoemaker-Levy 9 with Jupiter; to date, no such events have been observed on Earth.
Based on crater formation rates determined from the Earth's closest celestial partner, the Moon, astrogeologists have determined that during the last 600 million years, the Earth has been struck by 60 objects of a diameter of 5 km (3 miles) or more.
The smallest of these impactors would release the equivalent of ten million megatons of TNT and leave a crater 95 km (60 miles) across. For comparison, the largest nuclear weapon ever detonated, the Tsar Bomba, had a yield of 50 megatons.
Besides direct effect of asteroid impacts on a planet's surface topography, global climate and life, recent studies have shown that several consecutive impacts can have effect on the dynamo mechanism at a planet's core responsible for maintaining the magnetic field of the planet, and can eventually shut down the planet's magnetic field.