It is likely that most of the large impact craters on Earth have already been discovered and that others have been erased, according to a new calculation by a pair of Purdue Univ. graduate students.
"Over the past 3.5 billion years it is thought that more than 80 asteroids similar in size to, or larger than, the one which killed the dinosaurs have struck the Earth, leaving behind craters which are over 100 kilometers across, but our model suggests only about eight of these massive craters could still exist today," says Timothy Bowling, a graduate student in Purdue’s Department of Earth, Atmospheric and Planetary Sciences. "Geologists have already found six or seven such craters, so odds are not in the favor of those hoping to find the next big crater."
Researchers from Northwestern Univ. and the Univ. of New Mexico have reported evidence for potentially oceans worth of water deep beneath the U.S. Though not in the familiar liquid form — the ingredients for water are bound up in rock deep in the Earth’s mantle — the discovery may represent the planet’s largest water reservoir.
The presence of liquid water on the surface is what makes our “blue planet” habitable, and scientists have long been trying to figure out just how much water may be cycling between Earth’s surface and interior reservoirs through plate tectonics.
Pangaea’s Mountains Helped Earth Avoid Warming Last Time
Geochemists have calculated a huge rise in atmospheric CO2 was only avoided by the formation of a vast mountain range in the middle of the ancient supercontinent, Pangaea. This work is being presented to the European Association of Geochemistry’s Goldschmidt geochemistry conference.
Around 300 million years ago, plate tectonics caused the continents to aggregate into a giant supercontinent, known as Pangaea. The sheer size of the continent meant that much of the land surface was far from the sea, and so the continent became increasingly arid because of a lack of humidity. This aridity meant that rock weathering was reduced; normally, a reduction in rock weathering means that CO2 levels rise, yet in spite of this CO2 levels – which had been falling prior to the mountain formation- continued to drop, eventually undergoing the most significant drop in atmospheric CO2 of the last 500 million years. This phenomenon has remained unexplained, until now.
Understanding how clouds affect the climate has been a difficult proposition. What controls the makeup of the low clouds that cool the atmosphere or the high ones that trap heat underneath? How does human activity change patterns of cloud formation? Now, the research of the Weizmann Institute’s Prof. Ilan Koren suggests we may be nudging cloud formation in the direction of added area and height. He and his team have analyzed a unique type of cloud formation; their findings, which appeared recently in Science indicate that in pre-industrial times, there was less cloud cover over areas of pristine ocean than is found there today.
A group of scientists believe that a previously unexplained isotopic ratio from deep within the Earth may be a signal from material from the time before the Earth collided with another planet-sized body, leading to the creation of the moon. This may represent the echoes of the ancient Earth, which existed prior to the proposed collision 4.5 billion years ago. This work is being presented this week at the Goldschmidt conference, cosponsored by the European Association of Geochemistry.
The currently favored theory says that the moon was formed 4.5 billion years ago, when the Earth collided with a Mars-sized mass, which has been given the name “Theia.” According to this theory, the heat generated by the collision would have caused the whole planet to melt, before some of the debris cooled and spun off to create the moon. Now however, a group of scientists from Harvard Univ. believe that they have identified a sign that only part of the Earth melted, and that an ancient part still exists within the Earth’s mantle.
Some of the wind turbines generating electricity on Earth today grew out of technology developed in the 1990s for settlements on Mars.
Back then at NASA’s Ames Research Center, senior research scientist David Bubenheim and his colleagues worked on designing a complete ecological system to sustain astronauts on Mars. To generate electricity for the future Martians, they developed a hybrid concept combining two renewable sources: wind and sun.
At the surface, Antarctica is a motionless and frozen landscape. Yet, hundreds of miles down, the Earth is moving at a rapid rate, new research has shown.
The study, led by Newcastle Univ., and published this week in Earth and Planetary Science Letters, explains for the first time why the upward motion of the Earth’s crust in the Northern Antarctic Peninsula is currently taking place so quickly.
Floods of molten lava may sound like the stuff of apocalyptic theorists, but history is littered with evidence of such past events where vast lava outpourings originating deep in the Earth accompany the breakup of continents.
However, new research at Michigan State Univ. shows that the source of some of these epic outpourings may not be as deep as once thought. The results, published in the journal Geology, show that some of these lavas originated near the surface rather than deep within the mantle.
Streaming jets of high-speed matter produce some of the most stunning objects seen in space. Astronomers have seen them shooting out of young stars just being formed, X-ray binary stars and even the supermassive black holes at the centers of large galaxies.
Theoretical explanations for what causes those beam-like jets have been around for years, but now an experiment by French and American researchers using extremely high-powered lasers offers experimental verification of one proposed mechanism for creating them.
Since the discovery of the Antarctic ozone hole, scientists, policymakers, and the public have wondered whether we might someday see a similarly extreme depletion of ozone over the Arctic.
But a new MIT study finds some cause for optimism: ozone levels in the Arctic haven’t yet sunk to the extreme lows seen in Antarctica, in part because international efforts to limit ozone-depleting chemicals have been successful.
Western Hemisphere Gets Front-row Seat for Lunar Eclipse
North and South America, get ready for the first eclipse of the year.
Next Tuesday morning, April 15, 2014, the moon will be eclipsed by Earth’s shadow. This total lunar eclipse will be visible across the Western Hemisphere. The total phase will last 78 minutes, beginning at 3:06 a.m. EDT and ending at 4:24 a.m. EDT.
Using satellite imagery to monitor which volcanoes are deforming provides statistical evidence of their eruption potential, according to a new study led by the Univ. of Bristol published in Nature Communications.
ESA’s Sentinel satellite, launched this week, should allow scientists to test this link in greater detail and eventually develop a forecast system for all volcanoes, including those that are remote and inaccessible.
An international team of planetary scientists determined that the Moon formed nearly 100 million years after the start of the solar system, according to a paper published today in Nature. This conclusion is based on measurements from the interior of the Earth combined with computer simulations of the protoplanetary disk from which the Earth and other terrestrial planets formed.
The team of researchers from France, Germany and the U.S. simulated the growth of the terrestrial planets (Mercury, Venus, Earth and Mars) from a disk of thousands of planetary building blocks orbiting the Sun. By analyzing the growth history of the Earth-like planets from 259 simulations, the scientists discovered a relationship between the time the Earth was impacted by a Mars-sized object to create the Moon and the amount of material added to the Earth after that impact.
The Arctic has been undergoing significant changes in recent years. Average temperatures are rising twice as fast as they are elsewhere in the world. The extent and thickness of sea ice is rapidly declining. Such changes may have an impact on atmospheric conditions outside the region. Several hypotheses for how Arctic warming may be influencing mid-latitude weather patterns have been proposed recently. For example, Arctic warming could lead to a weakened jet stream resulting in more persistent weather patterns in the mid-latitudes. Or Arctic sea ice loss could lead to an increase of snow on high-latitude land, which in turn impacts the jet stream resulting in cold Eurasian and North American winters. These and other potential connections between a warming Arctic and mid-latitude weather are the subject of active research.
By the time you finish reading this story, you’ll be about 1,000 km closer to the planet Mars.
Earth and Mars are converging for a close encounter. As March gives way to April, the distance between the two planets is shrinking by about 300 km every minute. When the convergence ends in mid-April, the gulf between Earth and Mars will have narrowed to only 92 million km — a small number on the vast scale of the solar system.