Sentences with phrase «impacts of large asteroids»

«Understanding properties of silicate melts and glasses at ultra-high pressure is crucial to understand how the Earth has formed in its infancy, where impacts of large asteroids led to a completely molten Earth,» said Prescher.

Formed by the impact of a large asteroid or comet, Caloris is one of the largest, and possibly one of the youngest, basins in the Solar System.

Not exact matches

This group was probably one of the largest groups of dinosaurs to do so before the assumed asteroid impact 66 million years ago, which killed all non-bird dinosaurs.

Over 30 years ago, scientists proposed a large asteroid impact to explain the disparate elevations of Mars» northern and southern hemispheres; the theory became known as the «single impact hypothesis.»

New research by University of Colorado Boulder professor Stephen Mojzsis outlines a likely cause for these mysterious features of Mars: a colossal impact with a large asteroid early in the planet's history.

Sauropods, a group of large plant - eaters like Brontosaurus, may have started dying off 50 million years before the Chicxulub asteroid impact, they found.

The threat to our security is in the form of asteroids too small to be detected at long range but large enough to cause major catastrophes; NASA is now searching for asteroids one kilometer or larger in diameter, the impact of which could have global consequences.

In 1992 there was a meeting at Los Alamos National Laboratory to look at the consequences of large asteroid impacts on Earth.

Other theories involve planetary collisions that knock worlds off course or simply a large mass of materiallike an asteroid that jumps aboard and, by its mass and impact, tilts the once - flat orbit.

The discovery of coesite in the Chicxulub Crater under the Yucatan Peninsula in Mexico was significant evidence that this geological formation resulted from the impact of a comet or large asteroid.

Marchi's team proposes a novel, more efficient mechanism As the planet was pummeled by primordial asteroids — some larger than 100 kilometers in diameter — impacts would melt large volumes of rock, creating temporary lakes of lava.

New images indicate that most of the cavities are secondary impacts from rocks kicked up when large asteroids hit.

That feature — in which the crust thickness drops from 30 to about 10 miles (50 to 20 kilometers) over a large area that is the most visible feature on Mars — has been known to astronomers for more than 30 years and was long suspected to be due to an asteroid impact that flung most of the crust out the area.

The kind of asteroid needed to form the Martian dichotomy would fall in between that size and those of the rocks that formed other large craters, such as the South Pole — Aitken impact basin on the moon and the Hellas Basin in Mars's southern hemisphere, both more than 1,30 miles (2,000 kilometers) wide.

Millions of them are large enough to do serious damage in an impact, including the asteroid Apophis, which has a small chance of hitting Earth in 2036.

Three potential events were considered as part of their research, including; large asteroid impact, and exploding stars in the form of supernovae or gamma ray bursts.

This view of 1,000 - mile - wide Caloris basin — among the largest known asteroid impacts in the solar system — shows how lava (orange) filled the blast site before new craters excavated the original basin (purple).

But in spite of this, most civilian astronomers believe that tackling the catastrophically large but very rare impacts should be the first priority («How to destroy the doomsday asteroid», New Scientist, 6 June).

This period was apparently associated with increased meteoric impacts (around 100 times more frequent than today) associated with the break - up in the Main Asteroid Belt of the L - chondrite parent body — the largest documented asteroid breakup event over the past few billioAsteroid Belt of the L - chondrite parent body — the largest documented asteroid breakup event over the past few billioasteroid breakup event over the past few billion years.

The research contradicts other suggestions that the large valley networks on the red planet were the result of short - lived catastrophic flooding, lasting just hundreds to a few thousand years and perhaps triggered by asteroid impacts.

This artist's conception shows the immediate aftermath of a large asteroid impact around NGC 2547 - ID8, a 35 million - year - old star.

Asteroid impacts, especially the large ones, can excite atmospheric waves capable of revealing information about the internal structures of the planets that probably can not be obtained in any other way.

Because smaller chunks of asteroids drift from the point of collision faster than larger pieces do, these asteroid families become shaped like the letter «V.» Smaller pieces spread out far and wide from the original impact site, while larger fragments remain condensed at the point.

Mapping this microstructure to a large asteroid could help to predict the height and strength of the explosion, for example, or the likely impacted area of an impending meteorite strike after midair breakup.

«No sufficiently large asteroid currently exists in an Earth - crossing orbit; however, a comet of sufficient size to cause human extinction could impact the Earth, though the annual probability may be less than 10 − 8.

``... we lack compelling scenarios leading to the origin of iron meteorites... Early solar system collisions have been called upon to excavate this iron [from the cores of the largest asteroids], although numerical impact models have found this task difficult to achieve, particularly when it is required to occur many dozens of times, yet not a single time for asteroid Vesta.»

New high - resolution observations of Vesta by the DAWN mission reveal that the creatr is part of an even larger impact basin that was created by two massive overlapping impacts roughly around one and two billion years ago, which scooped out around one percent of the asteroid's estimated volume and blasted it into space (more from NASA's DAWN Mission and NEO Program; 1997 NASA / Hubble news release; Cornell University; Thomas et al, 1997; Kelley et al, 2003; and Jerry Coffrey, Universe Today, June 15 2009; and Russell et al, 2012; Jaumann et al, 2012; Marchi et al, 2012; and Schenk et al, 2012).

This artist's rendition shows how an asteroid collision might appear at the moment of impact, although the space rock in this image is considerably larger than the one Becker's team believes hit 250 million years ago.

Since then, astronomers have become increasingly a ware of the risk of future impacts, and major efforts are underway to discover and calculate the orbits for all asteroids larger than 1 km wide.

Eventually, one of my students asked about what a large asteroid impact would do to our Moon.

For example, even though the threat of asteroid impact is low, the threat is so large that it has to be taken seriously.

Some mechanisms for that are hypothesized, e.g. methane release from polar regions, increased melting of Greenland leading to stopping the Gulf Stream, rapid reduction of Arctic sea - ice and its positive feedback, collapse of Antarctic ice shelves, loss of the Amazon, large volcanoes, asteroid impacts, unexpected solar variation.

Suppose an astronomer discovered an asteroid heading for an impact with the Earth — how would the argument «On geological timescales Earth has been struck by lots of objects, including some much larger than this one» be taken?