Free Republic

The scans for MH370 revealed that the ocean crust rises and falls in waves that start at the Southeast Indian Ridge and continue outward. The ridge spreads about 35 millimeters in opposite directions every year, and the wave crests, where crust grew faster, are more than 100 kilometers long and repeat every 10-14 kilometers. The researchers estimated when each wave formed by comparing the bathymetry maps to independent measurements and models of the crust's magnetic field. ...Crustal rocks record the polarity of Earth's magnetic field as they form, allowing scientists to trace the age of different sections of ocean crust....

Earthquakes generate seismic waves below Earth's surface that travel thousands of miles. When the waves encounter changes in rock density, temperature or composition, they change speed, bend or scatter, producing echoes that can be detected. Echoes from nearby structures arrive more quickly, while those from larger structures are louder. By measuring the travel time and amplitude of these echoes as they arrive at seismometers in different locations, scientists can develop models of the physical properties of rock hidden below the surface. This process is similar to the way bats echolocate to map their environment Using a machine learning algorithm called...

Lambart and her colleagues from Wales and the Netherlands, sought to discover what the mantle looks like before it rises as lava at a mid-ocean ridge. They examined cores, drilled through the ocean crust, to look at cumulate minerals: the first minerals to crystallize when the magmas enter the crust. They analyzed the samples centimeter by centimeter to look at variations in isotopes of neodymium and strontium, which can indicate different chemistries of mantle material that come from different types of rock. The amount of isotope variability in the cumulates was seven times greater than that in the mid-ocean ridge...

The Earth has a second magnetic field, one generated by ocean currents. Researchers know little about it, but images captured by satellites show this invisible force generated by the world’s salty oceans in perfect detail. ... ESA released a video detailing the changes in the Earth’s magnetic field over a 24-hour period... ...“It’s a really tiny magnetic field. It’s about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth’s global magnetic field.”... Oceans may have a small contribution to the magnetic field that protects the planet from harmful cosmic rays, but it remains to be...

At first glance it looks like a potato-shaped asteroid flying through space. But this multi-coloured image is actually the Earth - and shows how gravity varies on different parts of the globe. The images were unveiled today by the team behind the GOCE satellite at a conference in Munich and are the most accurate ever released. The 'geoid' map, as it is known, is used to illustrate how oceans would look in the absence of currents or tides. The bright yellow colours show gravity at its strongest, while it is at its weakest in the blue areas. There appears to...

The reason that the ocean floor, especially the southern hemisphere oceans, is so poorly charted is that electromagnetic waves cannot penetrate the deep ocean (3-5 km = 2-3 mi). Instead, depths are commonly measured by timing the two-way travel time of an acoustic pulse. However because research vessels travel quite slowly (6m/s = 12 knots) it would take approximately 125 years to chart the ocean basins using the latest swath-mapping tools. To date, only a small fraction of the sea floor has been charted by ships. Fortunately, such a major mapping program is largely unnecessary because the ocean surface has...

Astronomy Picture of the Day 2001 November 13 A Gravity Map of Earth Credit: JPL, NASA Explanation: Is gravity the same over the surface of the Earth? No -- it turns out that in some places you will feel slightly heavier than others. The above relief map shows in exaggerated highs and lows where the gravitational field of Earth is relatively strong and weak. A low spot can be seen just off the coast of India, while a relative high occurs in the South Pacific Ocean. The cause of these irregularities is unknown since present surface features do not ...

Prof Claudia de Rham’s ‘massive gravity’ theory could explain why universe expansion is accelerating Cosmologists don’t enter their profession to tackle the easy questions, but there is one paradox that has reached staggering proportions. Since the big bang, the universe has been expanding, but the known laws of physics suggest that the inward tug of gravity should be slowing down this expansion. In reality, though, the universe is ballooning at an accelerating rate. Scientists have come up with a name – dark energy – for the mysterious agent that is allowing the cosmos to expand so rapidly and which is...

Our magnificent gravitational wave astronomers have done it again, adding to the detection collection a new collision between two neutron stars. On 25 April 2019, the LIGO interferometer detected two neutron stars around 520 million light-years away coming together and merging into a single object. It's called GW190425, and although it's only the second such collision astronomers have ever seen, it's already broadening our understanding of these colossal cosmic smash-ups.

If you venture too close to one of Earth's poles, you'll notice something rather strange happening to any gadgets using radio waves, satellite connections, or GPS. NASA is backing a range of initiatives to investigate the northern polar cusp, a funnel in space that's thought to be behind some of the weird space phenomena happening above the poles. This funnel, and the matching one at the South Pole, allows solar winds from the Sun to get right down to Earth's atmosphere – in other words, here the solar winds aren't reflected back out into space by the Earth's magnetic field,...

The processes that led to glaciation at the cratered poles of Mercury, the planet closest to the sun, have been modeled by a University of Maine-led research team. James Fastook, a UMaine professor of computer science and Climate Change Institute researcher, and James Head and Ariel Deutsch of Brown University, studied the accumulation and flow of ice on Mercury, and how the glacial deposits on the smallest planet in our solar system compare to those on Earth and Mars.Their findings, published in the journal Icarus, add to our understanding of how Mercury's ice accumulations—estimated to be less than 50 million...

One of the Moon's biggest craters was created by an asteroid more than 250km (150 miles) across, a study suggests. It smashed into the lunar surface about 3.8 billion years ago, forming Mare Imbrium - the feature also known as the right eye of the "Man in the Moon". Scientists say the asteroid was three times bigger than previously estimated and debris from the collision would have rained down on the Earth. The asteroid was so big it could be classified as a protoplanet - a space rock with the potential to become a fully formed world. Lead author Prof...

Explanation: What's that under the surface of Mercury? The robotic MESSENGER spacecraft that had been orbiting planet Mercury for the past four years had been transmitting its data back to Earth with radio waves of very precise energy. The planet's gravity, however, slightly changed this energy when measured on Earth, which enabled the reconstruction of a gravity map of unprecedented precision. Here gravitational anomalies are shown in false-color, superposed on an image of the planet's cratered surface. Red hues indicate areas of slightly higher gravity, which in turn indicates areas that must have unusually dense matter under the surface. The...

Scientists, including from The Australian National University (ANU), say they have detected a black hole swallowing a neutron star for the first time. Neutron stars and black holes are the super-dense remains of dead stars. On Wednesday 14 August 2019, gravitational-wave discovery machines in the United States and Italy detected ripples in space and time from a cataclysmic event that happened about 8,550 million trillion kilometres away from Earth.

The fact that no one has died from being struck by dark matter is enough proof to rule out certain ideas about the mysterious stuff, according to one new theory paper. There’s a conundrum facing physicists: Most of the universe’s mass appears to be missing, based on observations of the universe’s structure, how galaxies move, and how they seem to warp distant light. Thousands of physicists are now hunting for what might be producing these effects. But the mere fact that we’re alive here on Earth can offer some insight as to what dark matter isn’t, and the researchers behind...

Between May 29 and July 1919, an expedition organized by Cambridge astronomer Arthur Eddington and the Astronomer Royal Frank Dyson photographed first an eclipse of the Sun (May 29) and then, a month later, the stars where the Sun had been during the eclipse. By comparing the two photographs, the deflection of light caused by the Sun’s gravity could be precisely measured. Einstein’ gravity theory predicted a deflection value of 1.75 arcseconds, and Newton’s gravity theory a value half that. The results were announced in November 1919 to a joint meeting of the Royal Society and the Royal Astronomical Society....

Astronomers have been grappling with the mystery of dark matter for a long time, and I mean a looong time. The history of dark-matter investigations goes back at least to 1906, when physicist Henri Poincaré’s 1906 speculated about the amount of “matière obscure” in the Milky Way. Or really, it goes to back to 1846 and the first successful detection of dark matter: the discovery of the planet Neptune, whose existence had been inferred by its gravitational pull well before it was actually observed. Since then, scientists have identified many different dark components in space: collapsed stars, interstellar dust, hot...

The B-61-12 gravity bomb, a GPS-guided behemoth that’s been in development since 2008, can penetrate three meters of earth before detonating and dial up a nuclear yield of between 0.3 kilotons and 50 kilotons of devastating power. A message to Iran? Read on: An Air Force B-2 stealth bomber just completed the first test drop of an advanced nuclear gravity bomb, Military.com reported on June 30. The B-61-12 gravity bomb , a GPS-guided behemoth that’s been in development since 2008 , can penetrate three meters of earth before detonating and dial up a nuclear yield of between 0.3 kilotons and...

For decades, astrophysicists have pondered the odd movements of galaxies across the cosmos. The visible matter of the universe appears to be tugged around by an invisible counterpart, material that does not interact with surrounding matter in any observable way save gravity: dark matter. Refined measurements have since led scientists to hypothesize that 85 percent of all the matter in the universe is dark matter, while only 15 percent accounts for you, me, the planet, the stars, and everything else we can see. It's a satisfactory explanation for our observations that has one major problem: a dark matter particle has...

There are stars too faint to see in the night sky just a few light years away, yet a chance cosmic event gave us a glimpse of a star that would have otherwise been completely invisible due to its immense distance from Earth—a whopping 9 billion light-years away. A paper today in Nature Astronomy reports the discovery of the star, called MACS J1149 Lensed Star 1, or Icarus informally. Finding such a distant star is normally a tall order, but a larger object happened to pass in front of its home galaxy. When a large object passes in front of...