A Black Hole's Mass

There are no scales for weighing black holes. Yet astrophysicists from the Moscow Institute of Physics and Technology have devised a new way for indirectly measuring the mass of a black hole, while also confirming its existence. They tested the new method, reported in the Monthly Notices of the Royal Astronomical Society.

Active galactic nuclei are among the brightest and most mysterious objects in space. A galaxy is deemed active if it produces a thin long beam of matter and energy directed outward. Known as a relativistic jet, this phenomenon cannot be accounted for by the stars in the galaxy. The current consensus is that the jets are produced by some kind of "motors," termed galactic nuclei. While their nature is poorly understood, researchers believe that a spinning black hole could power an active galaxy.

Messier 87 in the Virgo constellation is an active galaxy that is closest to Earth, and also the one best studied. It has been observed on a regular basis since 1781, when it was first discovered as a nebula. It took some time before astronomers realized that it was a galaxy and its optical jet (discovered in 1918) was the first one ever to be observed.

The structure of the Messier 87 jet has been meticulously studied, with its plasma jet velocities mapped and the temperature and particle number density near the jet measured. The jet's boundary has been studied in such fine detail that researchers discovered it was inhomogeneous along its length, changing its shape from parabolic to conical. Originally discovered as an isolated case, this effect was later confirmed for a dozen other galaxies, though M87 remains the clearest example of the phenomenon.

The sheer bulk of observations allow for testing hypotheses regarding the structure of active galaxies, including the relation between the jet shape break and the black hole's gravitational influence. Jet behaviour and the existence of the supermassive black hole are two sides of the same coin: The former can be explained in terms of the latter while theoretical models of black holes are tested via jet observations.

Astrophysicists exploited the fact that the jet boundary is made up of segments of two distinct curves and used the distance between the core and the break of the jet, together with the jet's width, to indirectly measure the black hole mass and spin. To that end, MIPT scientists developed a method that combines a theoretical model, computer calculations and telescope observations.

The researchers are trying to describe the jet as a flow of magnetized fluid. In this case, the shape of the jet is determined by the electromagnetic field in it, which in turn depends on various factors, such as the speed and charge of jet particles, the electric current within the jet and the rate at which the black hole accretes matter. A complex interplay between these characteristics and physical phenomena gives rise to the observed break.

There is a theoretical model that predicts the break, so the team could determine which black hole mass results in the model reproducing the observed shape of the jet. This provided a new model for black hole mass estimation, a new measurement method, and a confirmation of the hypotheses underlying the theoretical model.

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Sizes of Black Holes

Black holes are singularities, points of infinitely small volume with infinite density. Such incredibly compact objects cause infinite curvature in the fabric of spacetime. Everything that falls into a black hole is sucked toward the singularity. At some distance away from the singularity, the escape velocity exceeds the speed of light, which is called “the point of no return,” although the technical term is Schwarzschild radius or event horizon. But what are the sizes of black holes?

There are a couple of different ways to conceptualize how BIG something is. The first is an object’s mass (how much matter it contains) and the second is its volume (how much space it takes up). However, the radius of a black hole’s event horizon is directly dependent on its mass, so in this case, we can answer the question, "How big is a black hole?" solely with respect to mass.

Different types of black holes have very different masses. Stellar-mass black holes are typically in the range of 10 to 100 solar masses, while the supermassive black holes at the centres of galaxies can be millions or billions of solar masses. The supermassive black hole at the centre of the Milky Way, Sagittarius A*, is 4.3 million solar masses. This is the only black hole whose mass has been measured directly by observing the full orbit of a circling star. Black holes grow by accreting surrounding matter and by merging with other black holes.

Because there is such a huge leap in sizes of black holes, between stellar-mass and supermassive black holes, it has been hypothesized that a class of intermediate-mass black holes also exists. The black holes would be hundreds or thousands of solar masses. There are a couple of candidate intermediate-mass black holes, such as HLX-1, which is estimated to be 20,000 solar masses.

Another hypothetical class of black holes is primordial black holes, which would have formed out of density fluctuations in the early universe. Generally, they would have been so tiny (the minimum mass would be the Planck mass) that they can only be properly described using quantum mechanics. But black holes evaporate through a process called Hawking Radiation. How quickly a black hole evaporates depends on its mass: the less massive a black hole, the more quickly it evaporates. For a primordial black hole to have survived to the present day, it would have to contain a few billion tons of mass, with a radius comparable to that of an atomic nucleus.

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Could Venus Have Supported Life 700 Million Years Ago?

The hellish planet Venus may have had a perfectly habitable environment for 2 to 3 billion years after the planet formed, suggesting life would have had ample time to emerge there, according to a new study. 

A study presented at the EPSC-DPS Joint Meeting 2019 by Michael Way of The Goddard Institute for Space Science gives a new view of Venus's climatic history and may have implications for the habitability of exoplanets in similar orbits. Venus may have been a temperate planet-hosting liquid water for 2-3 billion years until a dramatic transformation starting over 700 million years ago resurfaced around 80% of the planet.

In 1978, NASA's Pioneer Venus spacecraft found evidence that the planet may have once had shallow oceans on its surface. Since then, several missions have investigated the planet's surface and atmosphere, revealing new details on how it transitioned from an "Earth-like" planet to the hot, hellish place it is today.

To see if Venus might ever have had a stable climate capable of supporting liquid water, Dr. Way and his colleague, Anthony Del Genio, have created a series of five simulations assuming different levels of water coverage.

In all five scenarios, they found that Venus was able to maintain stable temperatures between a maximum of about 50 degrees Celsius and a minimum of about 20 degrees Celsius for around three billion years. A temperate climate might even have been maintained on Venus today had there not been a series of events that caused a release, or 'outgassing', of carbon dioxide stored in the rocks of the planet approximately 700-750 million years ago.

Three of the five scenarios studied by Way and Del Genio assumed the topography of Venus as we see it today and considered a deep ocean averaging 310 metres, a shallow layer of water averaging 10 metres and a small amount of water locked in the soil. For comparison, they also included a scenario with Earth's topography and a 310-metre ocean and, finally, a world completely covered by an ocean of 158 metres depth.

To simulate the environmental conditions at 4.2 billion years ago, 715 million years ago and today, the researchers adapted a 3-D general circulation model to account for the increase in solar radiation as our Sun has warmed up over its lifetime, as well as for changing atmospheric compositions.

Although many researchers believe that Venus is beyond the inner boundary of our Solar System's habitable zone and is too close to the Sun to support liquid water, the new study suggests that this might not be the case.

At 4.2 billion years ago, soon after its formation, Venus would have completed a period of rapid cooling and its atmosphere would have been dominated by carbon-dioxide. If the planet evolved in an Earth-like way over the next 3 billion years, the carbon dioxide would have been drawn down by silicate rocks and locked into the surface. By the second epoch modelled at 715 million years ago, the atmosphere would likely have been dominated by nitrogen with trace amounts of carbon dioxide and methane (similar to the Earth's today) and these conditions could have remained stable up until present times.

The cause of the outgassing that led to the dramatic transformation of Venus is a mystery, although probably linked to the planet's volcanic activity. One possibility is that large amounts of magma bubbled up, releasing carbon dioxide from molten rocks into the atmosphere. The magma solidified before reaching the surface and this created a barrier that meant that the gas could not be reabsorbed. The presence of large amounts of carbon dioxide triggered a runaway greenhouse effect, which has resulted in the scorching 462 degree average temperatures found on Venus today.

There are still two major unknowns that need to be addressed before the question of whether Venus might have been habitable can be fully answered. The first relates to how quickly Venus cooled initially and whether it was able to condense liquid water on its surface in the first place. The second unknown is whether the global resurfacing event was a single event or simply the latest in a series of events going back billions of years in Venus's history.

These findings are encouraging for those who believe that extra-terrestrial life exists. Think about it, if Venus had not undergone a massive resurfacing event (or a series of them), humanity would have only needed to look next-door for proof of extra-terrestrial life. It could have produced life of its own that would still be around today. Our one Solar System could have had not one, but two life-bearing planets.

These findings are likely to be encouraging for those who believe that Venus should be terraformed someday. Knowing that the planet once had a stable climate, and could maintain it despite its orbit, effectively means that any ecological engineering we do there would stick.

That means that Venus could someday be made into a balmy world that’s mostly covered with oceans with few large continents and extensive archipelagos.

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Water Vapour on the Habitable-Zone Exoplanet K2-18b

Astronomers have finally uncovered water vapour in the atmosphere of a super-Earth exoplanet orbiting within the habitable zone of its star. The find means that liquid water could also exist on the rocky world's surface, potentially even forming a global ocean.

The discovery, made with NASA's Hubble Space Telescope, serves as the first detection of water vapour in the atmosphere of such a planet. And because the planet, dubbed K2-18 b, likely sports a temperature similar to Earth, the newfound water vapour makes the world one of the most promising candidates for follow-up studies with next-generation space telescopes.

Planet K2-18 b sits some 110 light-years away in the constellation Leo, and it orbits a rather small red dwarf star that's roughly one-third the mass of our own Sun. Red dwarfs are infamous for being active stars that emit powerful flares, but the researchers point out that this particular star appears to be surprisingly docile.

This bodes well for the water-bearing planet, as its 33-day orbit brings it about twice as close to its star as Mercury is to the Sun. Given that the star is much cooler than the Sun, in the end, the planet is receiving similar radiation to the Earth. And based on calculations, the temperature of the planet is also similar to the temperature of the Earth.

Specifically, the paper suggests K2-18 b has a temperature between about –100 °F (–73 °C) and 116 °F (47 °C). For reference, temperatures on Earth can span from below –120 °F (–84 °C) in regions like Antarctica to above 120 °F (49 °C) in regions like Africa, Australia, and the Southwestern United States.

Although K2-18 b flaunts some of the most Earth-like features observed in an exoplanet so far — water, habitable temperatures, and a rocky surface — the researchers point out the world is still far from Earth-like. First off, K2-18 b is roughly twice the diameter of Earth, which makes it about eight times as massive. This puts K2-18 b near the upper limit of what we call a super-Earth — which typically refers to planets between about one and 10 Earth masses.

But the density of K2-18 b is what really cements it as a rocky planet. With a density about twice that of Neptune, K2-18 b has a composition most similar to Mars or the Moon. So, because the planet is believed to have a solid surface, and it's known to have an extended atmosphere with at least some water vapour, researchers say it's feasible that K2-18 b could actually be a water world with a global ocean covering its entire surface.

However, they cannot say for sure. The uncertainty is because Hubble can't probe the atmospheres of distant exoplanets in great detail. For instance, thanks to a sophisticated algorithm, the researchers were able to tease out the undeniable signal of water vapour in the atmosphere of K2-18 b, But they couldn't tell exactly how much water vapour is really there. So, in their paper, they took the conservative approach and gave a broad-range estimate for the abundance of water — somewhere between 0.01% and 50%.

In order to pin down exactly how much water is really on K2-18 b, the researchers say we'll have to wait for the next generation of advanced space telescopes to come online. Specifically, NASA's James Webb Space Telescope, scheduled for launch in 2021, and the European Space Agency's Atmospheric Remote-sensing Infrared Exoplanet Large survey (ARIEL) telescope, planned for launch in the late 2020s, are perfectly suited for the challenge.

The new research was published September 11 in Nature Astronomy

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It Rains on the Sun, But When And How?

Rain comes in various forms throughout the solar system water on Earth, methane/ethane on Titan and sulfuric acid on Venus. But did you know it also rains on the sun? Huge drops of plasma in the sun’s outer atmosphere, the corona, onto the scorching surface. 

Mason, a graduate student at The Catholic University of America, was searching for coronal rain: giant globs of plasma, or electrified gas, that drip from the Sun’s outer atmosphere back to its surface. But she expected to find it in helmet streamers, the million-mile tall magnetic loops — named for their resemblance to a knight’s pointy helmet — that can be seen protruding from the Sun during a solar eclipse. Computer simulations predicted the coronal rain could be found there. Observations of the solar wind, the gas escaping from the Sun and out into space, hinted that the rain might be happening.

But she was looking at the wrong place, So where was it?  Instead of the helmet streamers, the rain was found in a smaller kind of magnetic loop on the sun. It was there, just not in the place that the researchers had expected to find it. 

This research might help scientists to answer two mysteries why the sun's outer atmosphere is so much hotter than the star's surface and the source of the slow solar wind. The new data, collected using high-resolution telescopes mounted on NASA's Solar Dynamics Observatory, showed that coronal rain works similarly to rain on Earth — with a few exceptions.  

On Earth, rain is just one part of the larger water cycle, an endless tug-of-war between the push of heat and pull of gravity. In Earth’s hydrological cycle, water evaporates on the surface and rises up into the atmosphere. It then cools and condenses into clouds, and when there is enough moisture in the clouds, it falls back to the surface as rain. Coronal rain is a somewhat similar process, but with a completely different composition of the rain itself.

On the Sun coronal rain works similarly, but instead of 60-degree water you are dealing with a million-degree plasma.  Plasma, an electrically-charged gas, doesn’t pool-like water, but instead traces the magnetic loops that emerge from the Sun’s surface like a rollercoaster on tracks. At the loop’s foot points, where it attaches to the Sun’s surface, the plasma is superheated from a few thousand to over 1.8 million degrees Fahrenheit. It then expands up the loop and gathers at its peak, far from the heat source. As the plasma cools, it condenses and gravity lures it down the loop’s legs as coronal rain.

In previous theories, it was thought that coronal rain only occurred in closed loops, where the plasma heats and cools, but can’t escape into space. Mason’s work suggests, however, that the rain begins in a closed-loop, but then switches – through a process called magnetic reconnection – to an open one, like a train switching tracks. Some of the plasma will then escape, but some will fall back to the surface as rain. The plasma that does escape forms part of the slow solar wind.

How and why the Sun’s outer atmosphere is some 300 times hotter than its surface might have a strange connection to the plasma rain.  Simulations have shown that coronal rain only forms when the heat is applied to the very bottom of the loop. On the face of it, that observed fact doesn’t seem to make logical sense. As Mason found, the rain in the loops can provide a cutoff point to determine just where the corona is getting heated: If a loop has coronal rain on it, that means that the bottom 10% of it or less, is where coronal heating is happening.

Bottom line is Rain on the sun may sound nonsensical, but it is real and may help to solve some long-lingering puzzles about how our sun works. The researchers plan to study the smaller magnetic loop structures further using NASA's Parker Solar Probe, which launched in 2018 and has already travelled closer to the sun than any other spacecraft. 

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Is It Possible To Terraform Mars To Support Life As We Know It?

Science fiction writers have long featured terraforming, the process of creating an Earth-like or habitable environment on another planet, in their stories. Scientists themselves have proposed terraforming to enable the long-term colonization of Mars. A solution common to both groups is to release carbon dioxide gas trapped in the Martian surface to thicken the atmosphere and act as a blanket to warm the planet.

However, Mars does not retain enough carbon dioxide that could practically be put back into the atmosphere to warm Mars, according to a new NASA-sponsored study.  Transforming the inhospitable Martian environment into a place astronauts could explore without life support is not possible without technology well beyond today’s capabilities.

Although the current Martian atmosphere itself consists mostly of carbon dioxide, it is far too thin and cold to support liquid water, an essential ingredient for life. On Mars, the pressure of the atmosphere is less than 1% of the pressure of Earth’s atmosphere. Any liquid water on the surface would very quickly evaporate or freeze.

Proponents of terraforming Mars propose releasing gases from a variety of sources on the Red Planet to thicken the atmosphere and increase the temperature to the point where liquid water is stable on the surface. These gases are called “greenhouse gases” for their ability to trap heat and warm the climate. Carbon dioxide (CO2) and water vapour (H2O) are the only greenhouse gases that are likely to be present on Mars in sufficient abundance to provide any significant greenhouse warming.

Although studies investigating the possibility of terraforming Mars have been made before, the new result takes advantage of about 20 years of additional spacecraft observations of Mars. The researchers analyzed the abundance of carbon-bearing minerals and the occurrence of CO2 in polar ice using data from NASA’s Mars Reconnaissance Orbiter and Mars Odyssey spacecraft, and used data on the loss of the Martian atmosphere to space by NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft.

The results suggest that there is not enough CO2 remaining on Mars to provide significant greenhouse warming. We don't have the technology to be put desire quantity of greenhouse gases into the atmosphere yet, in addition, most of the CO2 present on Mars is not accessible and could not be readily mobilized.

Although Mars has significant quantities of water ice that could be used to create water vapour, previous analyses show that water cannot provide significant warming by itself; temperatures do not allow enough water to persist as vapour without first having significant warming by CO2, according to the team. Also, while other gases such as the introduction of chloroflorocarbons or other fluorine-based compounds have been proposed to raise the atmospheric temperature, these gases are short-lived and would require large-scale manufacturing processes, so they were not considered in this study.

The atmospheric pressure on Mars is around 0.6% of Earth’s. With Mars being further away from the Sun, researchers estimate a CO2 pressure similar to Earth’s total atmospheric pressure is needed to raise temperatures enough to allow for stable liquid water. The most accessible source is CO2 in the polar ice caps; it could be vaporized by spreading dust on it to absorb more solar radiation or by using explosives. However, vaporizing the ice caps would only contribute enough CO2 to double the Martian pressure to 1.2% of Earth’s, according to the new analysis.

Another source is CO2 attached to dust particles in Martian soil, which could be heated to release the gas. The researchers estimate that heating the soil could provide up to 4% of the needed pressure. A third source is carbon locked in mineral deposits. Using the recent NASA spacecraft observations of mineral deposits, the team estimates the most plausible amount will yield less than 5% of the required pressure, depending on how extensive deposits buried close to the surface may be. Just using the deposits near the surface would require extensive strip mining, and going after all the CO2 attached to dust particles would require strip mining the entire planet to a depth of around 100 yards. Even CO2 trapped in water-ice molecule structures, should such “clathrates” exist on Mars, would likely contribute less than 5% of the required pressure, according to the team.

Carbon-bearing minerals buried deep in the Martian crust might hold enough CO2 to reach the required pressure, but the extent of these deep deposits is unknown, not evidenced by orbital data, and recovering them with current technology is extremely energy-intensive, requiring temperatures above 300 degrees Celsius (over 572 degrees Fahrenheit). Shallow carbon-bearing minerals are not sufficiently abundant to contribute significantly to greenhouse warming, and also require the same intense processing.

Although the surface of Mars is inhospitable to known forms of life today, features that resemble dry riverbeds and mineral deposits that only form in the presence of liquid water provide evidence that, in the distant past, the Martian climate supported liquid water at the surface. But solar radiation and solar wind can remove both water vapor and CO2 from the Martian atmosphere.

Both MAVEN and the European Space Agency’s Mars Express missions indicate that the majority of Mars’ ancient, potentially habitable atmosphere has been lost to space, stripped away by solar wind and radiation. Of course, once this happens, that water and CO2 are gone forever. Even if this loss were prevented somehow, allowing the atmosphere to build up slowly from outgassing by geologic activity, current outgassing is extremely low; it would take about 10 million years just to double Mars’ current atmosphere, according to the team.

Answer to the question is yes it is possible to Terraform Mars to support Life as we know it. But with currently available technology we can't do it.

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How Does Solar Sail Work?

Solar sails are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. These particles of light have no mass and yet when they impinge on something, they can impart momentum and provide a tiny push. You get shoved by photons every time you step out into the sunshine but their incredibly small force is essentially unnoticeable to your body. 

In space, things take a different turn. The laws of physics state that every action must have an equal and opposite reaction, so, when photons from the sun bounce off a spaceship, the ship is propelled ever so slightly in a direction away from the sun. With a single photon, the change is negligible but a large collection of them can provide significant thrust. 

Place a large, flat, mirror-like sheet in front of a spacecraft and the sun's power will push it forward. The material must also be strong and gossamer-thin in order to catch and control the sunlight. Solar sails can tack like regular sails to travel in many directions, according to the Planetary Society. The technology has an advantage over other propulsion methods because a ship does not need to carry fuel wherever it goes, instead, relying on the freely-available light of stars. 

Since they get a continuous push from the sun, solar-sail-powered ships can constantly accelerate as they journey to the edge of the solar system, achieving super-fast speeds that would be much more difficult for chemical rockets. Alternatively, solar sails can also be driven by gargantuan laser beams.

NASA tested the concept of solar sailing in 1974 with its Mariner 10 spacecraft, which was designed to fly past Venus and Mercury. When the probe ran out of fuel, mission control turned its solar panels to just the right angle to catch the sun's rays and push the spacecraft forward. 

The first human-made solar sail to successfully fly was the Japanese Space Exploration Agency's Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS) spacecraft. The robot deployed its 46-foot-wide (14 meters) sail in June 2010 and proved the ability to control its direction and change orientation on command. 

That same year, NASA launched the tiny NanoSail-D demonstrator mission, which had a diamond-shaped sail 10 feet (3 m) to a side. The probe unfurled its solar sail in 2011 and circled the Earth for eight months before burning up in the atmosphere. Lightweight and with little room to carry fuel, small satellites are thought to be ideal candidates for this type of propulsion. 

In 2015, the Planetary Society launched the LightSail-1 spacecraft into orbit, which sported a 344-square-foot (32-square-m) solar sail, about the size of a boxing ring. Despite some successes, and a selfie or two, the mission suffered from technical glitches and eventually stopped transmitting signals before entering the atmosphere a few weeks after it was launched. 

But the Planetary Society is back at it and has high hopes for their new LightSail-2 mission. The craft is about the size of a bread loaf and intends to release a similarly-sized sail as its predecessor. Mission planners said that one-day solar-sail-driven ships could travel to the edge of the solar system or beyond. 

The Breakthrough Starshot Initiative intends to do just that, sending lightweight microchip-sized probes to explore the nearest star system, Alpha Centauri, which is 4.3 light-years away. Announced in 2016, the $100-million venture is investigating the feasibility of using a colossal Earth-based laser to accelerate the chips to 20% the speed of light and reaching Alpha Centauri in only 20 years. 

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NASA’s James Webb Space Telescope

Reaching a major milestone, engineers have successfully connected the two halves of NASA’s James Webb Space Telescope for the first time at Northrop Grumman’s facilities in Redondo Beach, California. Once it reaches space, NASA's most powerful and complex space telescope will explore the cosmos using infrared light, from planets and moons within our solar system to the most ancient and distant galaxies.

To combine both halves of Webb, engineers carefully lifted the Webb telescope (which includes the mirrors and science instruments) above the already-combined sun shield and spacecraft using a crane. Team members slowly guided the telescope into place, ensuring that all primary points of contact were perfectly aligned and seated properly. The observatory has been mechanically connected; the next steps will be to electrically connect the halves and then test the electrical connections. 

“The assembly of the telescope and its scientific instruments, sun shield and the spacecraft into one observatory represents an incredible achievement by the entire Webb team,” said Bill Ochs, Webb project manager for NASA Goddard Space Flight Center in Greenbelt, Maryland.  “This milestone symbolizes the efforts of thousands of dedicated individuals for over more than 20 years across NASA, the European Space Agency, the Canadian Space Agency, Northrop Grumman, and the rest of our industrial and academic partners.”

Next up for Webb testing, engineers will fully deploy the intricate five-layer sun shield, which is designed to keep Webb's mirrors and scientific instruments cold by blocking infrared light from the Earth, Moon and Sun. The ability of the sunshield to deploy to its correct shape is critical to mission success.

“This is an exciting time to now see all Webb’s parts finally joined together into a single observatory for the very first time,” said Gregory Robinson, the Webb program director at NASA Headquarters. “The engineering team has accomplished a huge step forward and soon we will be able to see incredible new views of our amazing universe.”

Both of the telescope’s major components have been tested individually through all of the environments they would encounter during a rocket ride and orbiting mission a million miles away from Earth. Now that Webb is a fully assembled observatory, it will go through additional environmental and deployment testing to ensure mission success. The spacecraft is scheduled to launch in 2021.

Webb will be the world's premier space science observatory. It will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

The James Webb Space Telescope (sometimes called JWST or Webb) will be a large infrared telescope with a 6.5-meter primary mirror.  The telescope will be launched on an Ariane 5 rocket from French Guiana in 2021.

Webb will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.

Several innovative technologies have been developed for Webb. These include a primary mirror made of 18 separate segments that unfold and adjust to shape after launch. The mirrors are made of ultra-lightweight beryllium. Webb’s biggest feature is a tennis court-sized five-layer sunshield that attenuates heat from the Sun more than a million times. The telescope’s four instruments - cameras and spectrometers - have detectors that are able to record extremely faint signals. One instrument (NIRSpec) has programmable micro shutters, which enable observation up to 100 objects simultaneously. Webb also has a cryocooler for cooling the mid-infrared detectors of another instrument (MIRI) to a very cold 7 K so they can work.

Webb is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center is managing the development effort. The main industrial partner is Northrop Grumman; the Space Telescope Science Institute will operate Webb after launch.

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Why Does Earth's Magnetic Field Flip?

Earth's magnetic field has flipped many times over the last billion years, according to the geologic record. But only in the past decade have scientists developed and evolved a computer model to demonstrate how these reversals occur.

Based on a set of physics equations that describe what scientists believe are the forces that create and maintain the magnetic field, Glatzmaier and colleague Paul Roberts at the University of California, Los Angeles, created a computer model to simulate the conditions in the Earth's interior.

The computer-generated magnetic field even reverses itself, allowing scientists to examine the process. Scientists believe Earth's magnetic field is generated deep inside our planet. There, the heat of the Earth's solid inner core churns a liquid outer core composed of iron and nickel. The churning acts like convection, which generates electric currents and, as a result, a magnetic field.

This magnetic field shields most of the habited parts of our planet from charged particles that emanate from space, mainly from the sun. The field deflects the speeding particles toward Earth's Poles.

Our planet's magnetic field reverses about once every 200,000 years on average. However, the time between reversals is highly variable. The last time Earth's magnetic field flipped was 780,000 years ago, according to the geologic record of Earth's polarity.

The information is captured when molten lava erupts onto Earth's crust and hardens, much in the way that iron filings on a piece of cardboard align themselves to the field of a magnet held beneath it.

Most scientists believe our planet's magnetic field is sustained by what's known as the geodynamo. The term describes the theoretical phenomenon believed to generate and maintain Earth's magnetic field. However, there is no way to peer 4,000 miles (6,400 kilometres) into Earth's centre to observe the process in action.

That inability spurred Glatzmaier and Roberts to develop their computer model in 1995. Since then, they have continued to refine and evolve the model using ever more sophisticated and faster computers.

The model is essentially a set of equations that describe the physics of the geodynamo. The equations are continually solved, each solution advancing the clock forward about a week. At its longest stretch, the model ran the equivalent of 500,000 years, Glatzmaier said.

By studying the model, the scientists discovered that, as the geodynamo generates new magnetic fields, the new fields usually line up in the direction of the existing magnetic field. But once in a while a disturbance will twist the magnetic field in a different direction and induce a little bit of a pole reversal.

These bits of a pole reversal are referred to as instabilities. They constantly occur in the fluid flow of the core, tracking through it like little hurricanes, though at a much slower pace—about one degree of latitude per year.

Typically, instabilities are temporary. But on very rare occasions, conditions are favourable enough that the reversed polarity gets bigger and bigger as the original polarity decays. If this new polarity takes over the entire core, it causes a pole reversal.

Peter Olson, a geophysicist at Johns Hopkins University in Baltimore, Maryland, said scientists can now pinpoint the core-mantle boundary where these instabilities in the magnetic field are happening.

One such disturbance Olson has been observing recently formed over the east-central Atlantic Ocean. Like a little hurricane, the anomaly swept toward the Caribbean and is moving up in the direction of North America.

Instabilities such as this are causing Earth's magnetic field to weaken. Today the field is about 10% weaker than it was when German mathematician Carl Friedrich Gauss first began measuring it in 1845. Some scientists speculate the field is headed for a reversal.

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Magnetic North Is Shifting Fast. But Why?

Like most planets in our solar system, the Earth has its own magnetic field. Thanks to its largely molten iron core, our planet is, in fact, a bit like a bar magnet. It has a north and south magnetic pole, separate from the geographic poles, with a field connecting the two. This field protects our planet from radiation and is responsible for creating the northern and southern lights – spectacular events that are only visible near the magnetic poles.

Our planetary magnetic field has many advantages. For over 2,000 years, travellers have been able to use it to navigate across the globe. Some animals even seem to be able to find their way thanks to the magnetic field. But, more importantly than that, our geomagnetic field helps protect all life on Earth.

Earth’s magnetic field extends hundreds of thousands of kilometres out from the centre of our planet – stretching right out into interplanetary space, forming what scientists call a “magnetosphere”. This magnetosphere helps to deflect solar radiation and cosmic rays, preventing the destruction of our atmosphere. This protective magnetic bubble isn’t perfect though, and some solar matter and energy can transfer into our magnetosphere.

Since Earth’s magnetic field is created by its moving, molten iron core, its poles aren’t stationary and they wander independently of one another. In fact, since its first formal discovery in 1831, the north magnetic pole has travelled over 2,000km from the Boothia Peninsula in the far north of Canada to high in the Arctic Sea. This wandering has generally been quite slow, around 9km a year, allowing scientists to easily keep track of its position. But since the turn of the century, this speed has increased to 50km a year. The south magnetic pole is also moving, though at a much slower rate (10-15km a year).

This rapid wandering of the north magnetic pole has caused some problems for scientists and navigators alike. Computer models of where the north magnetic pole might be in the future have become seriously outdated, making accurate compass-based navigation difficult. Although GPS does work, it can sometimes be unreliable in the polar regions. In fact, the pole is moving so quickly that scientists responsible for mapping the Earth’s magnetic field were recently forced to update their model much earlier than expected.

In the meantime, scientists are working to understand why the magnetic field is changing so dramatically. Geomagnetic pulses, like the one that happened in 2016, might be traced back to ‘hydromagnetic’ waves arising from deep in the core. And the fast motion of the north magnetic pole could be linked to a high-speed jet of liquid iron beneath Canada.

The jet seems to be smearing out and weakening the magnetic field beneath Canada. Which means that Canada is essentially losing a magnetic tug-of-war with Siberia.

The location of the north magnetic pole appears to be governed by two large-scale patches of the magnetic field, one beneath Canada and one beneath Siberia. The Siberian patch is winning the competition. Which means that the world’s geomagnetists will have a lot to keep them busy for the foreseeable future.

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What Is Geothermal Energy?

Geothermal energy is heat derived within the sub-surface of the earth. It is contained in the rocks and fluids beneath the earth’s crust and can be found as far down to the earth’s hot molten rock, magma. Water or steam carry the geothermal energy to the Earth’s surface. Depending on its characteristics, geothermal energy can be used for heating and cooling purposes or be harnessed to generate clean electricity.

This key renewable source covers a significant share of electricity demand in countries like Iceland, El Salvador, New Zealand, Kenya, and the Philippines and more than 90% of heating demand in Iceland. The main advantages are that it is not depending on weather conditions and has very high capacity factors; for these reasons, geothermal power plants are capable of supplying baseload electricity, as well as providing ancillary services for short and long-term flexibility in some cases. It's clean and sustainable.

Many technologies have been developed to take advantage of geothermal energy like 1. Geothermal Electricity Production ( Generating electricity from the earth's heat. ) 2. Geothermal Direct Use ( Producing heat directly from hot water within the earth. ) 3. Geothermal Heat Pumps ( Using the shallow ground to heat and cool buildings. ). 

To produce power from geothermal energy, wells are dug a mile deep into underground reservoirs to access the steam and hot water there, which can then be used to drive turbines connected to electricity generators. There are three types of geothermal power plants; dry steam, flash and binary. 

Dry steam is the oldest form of geothermal technology and takes the steam out of the ground and uses it to directly drive a turbine. Flash plants use high-pressure hot water into cool, low-pressure water whilst binary plants pass hot water through a secondary liquid with a lower boiling point, which turns to vapour to drive the turbine.

However, there are some drawbacks to the energy source. Despite low CO2 production geothermal has been associated with other emissions like sulphur dioxide and hydrogen sulphide. Similar to fracking, geothermal power plants have been the cause of mini tremors in the area they operate in and also has a high initial cost to build. 

It is also described as “the most location-specific energy source known to man” due to its activity being along the tectonic plates of the earth’s crust.  As such, it is limited to countries such as the aforementioned US and Iceland, alongside Kenya and Indonesia.

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