Sentences with phrase «by meteorite impact»

Meteor Crater in Arizona, formed by a meteorite impact 50,000 years ago, contains bits of a hard, compressed form of silica called stishovite.

Gale Crater was formed by meteorite impact early in the history of Mars, and it was subsequently filled with sediments transported by flowing water.

Exquisite telescopic photographs of the lunar surface had existed for decades before the Apollo missions to the Moon, but they did not resolve the controversy of the origin of lunar craters were they formed by meteorite impact or by volcanic eruption?

At least 17 people are said to have been killed by meteorite impact.

Astronomers had predicted that dust created by meteorite impacts should coat all the moons evenly, giving their surfaces a uniform look.

GRAIL's discoveries include the fact that the moon's crust is thinner and more fractured by meteorite impacts than scientists had suspected (SN Online: 12/6/12).

Duke's Apollo 16 mission returned with rocks that proved the moon's highlands had been shaped more by meteorite impacts than ancient volcanoes.

Lunar regolith is made from solid moon rock that has been ground down over eons by meteorite impacts.

Scientists suggest signs of life from under Mars» surface may not survive in rocks excavated by some meteorite impacts.

Not exact matches

[241] The attractions and major tourist destinations of Ghana include a warm, tropical climate year - round; diverse wildlife; exotic waterfalls such as Kintampo Waterfalls and the largest waterfall in west Africa, Wli Waterfalls; Ghana's coastal palm - lined sandy beaches; caves; mountains, rivers; meteorite impact crater and reservoirs and lakes such as Lake Bosumtwi or Bosumtwi meteorite crater and the largest man - made lake in the world by surface area, Lake Volta; dozens of castles and forts; UNESCO World Heritage Sites; nature reserves and national parks.

Based on their analysis, Mars» metals are best explained by a massive meteorite collision about 4.43 billion years ago, followed by a long history of smaller impacts.

The meteorite is made of volcanic rock, and the presence of water in it suggests that crustal rocks on Mars interacted with surface water that was delivered by volcanic activity, near - surface reservoirs or by impacting comets, Agee says.

The previous five were caused by natural events — meteorite impacts and global temperature change — but this latest is decidedly human - generated, primarily through habitat destruction.

The team speculate that a meteorite impact, moonquake, or pressure created by gravitational tugs from the Earth could have triggered a minor ceiling collapse in the tube.

Lonsdaleite forms only under the extreme pressure and heat accompanying meteorite impacts, while wurtzite boron nitride is a by - product of intense volcanic eruption.

Of the 731 rock samples the Apollo 16 astronauts brought home in April 1972, nearly all were breccia, composites formed of fragments fused together — probably by the heat and pressure of meteorite impacts.

The stone's noble gas content supports an extraterrestrial origin, while the presence of tiny diamonds — larger than nanodiamonds found in a common kind of meteorite called chondrites, but similar in size to diamond aggregates known to be formed by impacts — supports a cometary origin.

The glass itself, one large polished piece of which has a prominent place in a necklace that belonged to Egyptian pharaoh Tutankhamen, has been dated to 28.5 million years and has long been thought to be the result of a meteorite impact or an airburst caused by a comet breaking up in Earth's atmosphere.

«We find that the end - Cretaceous mass extinction was caused by a combination of the volcanism and meteorite impact, delivering a theoretical «one - two punch,»» said Petersen, first author of a paper scheduled for online publication July 5 in the journal Nature Communications.

The earlier evidence for water on the moon hinted only at small deposits near the poles, probably left there by the impact of icy meteorites.

In a first - of - its - kind collision chamber at Argonne National Laboratory, physicist Yogendra Gupta of Washington State University and his colleagues mimicked a meteorite impact by firing a lithium fluoride bullet at a graphite disk at 5.1 kilometers per second.

Discovered in 1984 in Allan Hills, Antarctica, researchers believe that meteorite ALH84001 struck Earth some 3.5 to four billion years ago after being kicked up from the Martian surface and into space by the impact of another meteorite.

Last year, researchers found that in conditions mimicking those sparked by a comet or meteorite impact, intense heat and pressure converted formamide (which forms when hydrogen cyanide reacts with water) and other simple substances into the four information - bearing nucleobases in RNA, a likely genetic precursor to DNA.

10 Meteorite impacts have been blamed for hundreds of injuries, but only one has been verified by scientists.

Lakes may form when meteorite impacts heat ice in the crust or when underground reservoirs of water kept liquid by geothermal heat leak onto the surface.

They simulated a meteorite impact on early Earth by firing a high - power laser at samples of formamide — a liquid that would have existed on our primordial planet.

They reasoned that without continual renewal, the surfaces of such bodies should have become densely covered with craters as a result of impacts by meteorites and comets over the 4.5 billion years that they have existed.

In 2009, this team reported the formation of the simplest amino acid, glycine, by simulating meteorite impacts.

Quantifying the release of climate - active gases by large meteorite impacts with a case study of Chicxulub.

«If you think about a mass extinction caused by catastrophic event such as a meteorite impacting Earth, you might imagine all species are equally likely to die,» Blonder said.

The graphite fragments, Steele says, «are a remnant of basically a carbon - rich dust after an impact from a meteorite containing carbon, or the carbon may have condensed from a gas» released by an impact.

Tornabene L. L. et al. (2013), Meter - to decameter - scale morphology of melt rocks, breccias, bedrock and structures in central uplifts revealed by the Mars Reconnaissance Orbiter, Large Meteorite Impacts V, held Aug. 5 - 9th, 2013 in Sudbury, ON.

Scientists have argued for half a century about the existence of a form of diamond called lonsdaleite, which is associated with impacts by meteorites and asteroids.

The Cool Stars 18 Public Lecture is sponsored by The Barringer Crater Company, owners since 1903 of The Barringer Meteorite Crater more commonly known as Meteor Crater, Earth's first proven and best preserved impact site.

On October 4, 2010, some astronomers announced that asteroid 21 Lutetia may be covered by a 2,000 - feet (600 - meter) deep layer of dusty debris generated by billions of years of meteorite impacts (Jonathan Amos, BBC News, October 4, 2010).

There are over 3,000 cenotes in Mexico, mostly in the area covered by the Chicxulub crater, the crater that was formed after the meteorite impact that extinguished dinosaurs.

Could some be introduced by meteorite / astroid impacts, volcanic activity, or different emission of radon gas from Earth's interior?

Since the hole was spotted in mid-July by a helicopter pilot, conjecture has abounded about how the 30 - metre - wide crater was formed — a gas or missile explosion, a meteorite impact and alien involvement have all been suggested.

For three decades, the dominant explanation for this mass extinction has been that it was probably caused by the impact of a large meteorite.

These can be caused by sub-marine landslides, seafloor deformations due to earthquakes, or the impact of a large meteorite.

The impact of the meteorite that wiped out the dinosaurs released vast amounts of CO2 from vaporising carbonate - rich rocks, pushing atmospheric CO2 levels up to approx 2,300 ppm resulting in a climatic forcing of +12 W - m -LRB--) 2 that would have been sufficient to warm the Earth's surface by 7.5 °C, in the absence of counter forcing by sulfate aerosols.