Sentences with phrase «formed by meteorite»

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?

Not exact matches

Precious Metals the Result of Meteorite Bombardment, Rock Analysis Finds Sep. 9, 2011 — Ultra high precision analyses of some of the oldest rock samples on Earth by researchers at the University of Bristol provides clear evidence that the planet's accessible reserves of precious metals are the result of a bombardment of meteorites more than 200 million years after Earth was formed.

Sep. 9, 2011 — Ultra high precision analyses of some of the oldest rock samples on Earth by researchers at the University of Bristol provides clear evidence that the planet's accessible reserves of precious metals are the result of a bombardment of meteorites more than 200 million years after Earth was formed.

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.

By studying the magnetic orientations in pristine samples of ancient meteorites that formed 4.563 billion years ago, the team determined that the solar nebula lasted around 3 to 4 million years.

Current thinking is that these tiny diamonds can form in three ways: enormous pressure shockwaves from high - energy collisions between the meteorite «parent body» and other space objects; deposition by chemical vapor; or, finally, the «normal» static pressure inside the parent body, like most diamonds on Earth.

New work from a team of Carnegie cosmochemists published by Science Advances reports analyses of carbon - rich dust grains extracted from meteorites that show that these grains formed in the outflows from one or more type II supernovae more than two years after the progenitor stars exploded.

They moreover show that the light signature emitted by Phobos and Deimos is incompatible with that of the primordial matter that formed Mars (meteorites such as ordinary chondrite, enstatite chondrite and / or angrite).

Tiny carbon nuggets in meteorites from Mars were formed by cooling magma, not left by ancient alien microbes.

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.

In 2000, for instance, Malin published pictures of small gullies that, judging from the absence of meteorite craters in them, seem to have been formed by running water within the past few million years.

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.

The researchers were looking at rocks from the Ries crater (inset) of southern Germany, a 24 - kilometer - wide depression formed about 14.6 million years ago by a meteorite crashing into Earth with the force of 1.8 million Hiroshima bombs.

Ben Weiss at the Massachusetts Institute of Technology and his colleagues tested three meteorites that cooled a mere 3.8 million years after the sun began to form, a date pinned down by the ratio of their uranium and lead content.

In contrast, the meteorite analyzed by Lapen's research team was formed 2.4 billion years ago and suggests that it was ejected from one of the longest - lived volcanic centers in the solar system.

After the meteor was sighted streaking through the sky on 22 April, meteorite hunters found fragments of the rock, identified by the «fusion crust» that forms when it burns in the atmosphere.

By looking at tungsten and molybdenum isotopes on iron meteorites, the team, made up of scientists from Lawrence Livermore National Laboratory and Institut für Planetologie at the University of Münsterin Germany, found that meteorites are made up from two genetically distinct nebular reservoirs that coexisted but remained separated between 1 million and 3 - 4 million years after the solar system formed.

Eventually, they landed on a second asteroid, where they were buried by other rock — until that asteroid too shed them in the form of the meteorites that carried them to Earth.

The composition of the matter from which the solar system formed is deduced from that of stony meteorites called chondrites and from the composition of the Sun's atmosphere, supplemented by data acquired from spectral observations of hot stars and gaseous nebulas.

Experiments at Berkeley Lab are helping to retrace the chemical steps by which complex hydrocarbons like pyrene could form in the Murchison meteorite and other meteorites.

Another NASA research group, led by Kathie Thomas - Keprta of NASA's Johnson Space Center, report in the same issue of PNAS that the magnetite crystals inside the meteorite are similar to those formed by «modern» magnetotactic bacteria now living on Earth.

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.

But by showing how carbonate globules, similar to those in the martian meteorite, formed without the involvement of living organisms, Steele and his colleagues have made less compelling the argument that the visiting rock from our planetary neighbor contains evidence of life.

The Mars rock made headlines in 1996 when researchers, led by David McKay, from NASA's Johnson Space Center, claimed in the journal Science that the meteorite contained evidence of possible Red Planet life forms.

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.

The buzz is building over a paper by Richard Hoover, an award - winning astrobiologist at NASA's Marshall Space Flight Center, concluding that filaments and other features found in the interior of three specimens of a rare class of meteorite appear to be fossils of a life form strongly resembling cyanobacteria.

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.