blazepress:

Filming a rainbow when suddenly.

blazepress:

Filming a rainbow when suddenly.

xysciences:

A gif representing nuclear fusion and how it creates energy. 
[Click for more interesting science facts and gifs]

For those who don’t understand the GIF. It illustrates the Deuterium-Tritium fusion; a deuterium and tritium combine to form a helium-4. Most of the energy released is in the form of the high-energy neutron.
Nuclear fusion has the potential to generate power without the radioactive waste of nuclear fission (energy from splitting heavy atoms  into smaller atoms), but that depends on which atoms you decide to fuse. Hydrogen has three naturally occurring isotopes, sometimes denoted ¹H, ²H, and ³H. Deuterium (²H) - Tritium (³H) fusion (pictured above) appears to be the best and most effective way to produce energy. Atoms that have the same number of protons, but different numbers of neutrons are called isotopes (adding a proton makes a new element, but adding a neutron makes an isotope of the same atom). 
The three most stable isotopes of hydrogen: protium (no neutrons, just one proton, hence the name), deuterium (deuterium comes from the Greek word deuteros, which means “second”, this is in reference two the two particles, a proton and a neutron), and tritium (the name of this comes from the Greek word “tritos” meaning “third”, because guess what, it contains one proton and two neutrons). Here’s a diagram
Deuterium is abundant, it can be extracted from seawater, but tritium is a  radioactive isotope and must be either derived(bred) from lithium or obtained in the operation of the deuterium cycle. Tritium is also produced naturally in the upper atmosphere when cosmic rays strike nitrogen molecules in the air, but that’s extremely rare. It’s also a by product in reactors producing electricity (Fukushima Daiichi Nuclear Power Plant). Tritium is a low energy beta emitter (unable to penetrate the outer dead layer of human skin), it has a relatively long half life and short biological half life. It is not dangerous externally, however emissions from inhaled or ingested beta particle emitters pose a significant health risk.
During fusion (energy from combining light elements to form heavier ones), two atomic nuclei of the hydrogen isotopes deuterium and tritium must be brought so close together that they fuse in spite of the strongly repulsive electrostatic forces between the positively charged nuclei. So, in order to accomplish nuclear fusion, the two nuclei must first overcome the electric repulsion (coulomb barrier ) to get close enough for the attractive nuclear strong force (force that binds protons and neutrons together in atomic nuclei) to take over to fuse the particles. The D-T reaction is the easiest to bring about, it has the lowest energy requirement compared to energy release. The reaction products are helium-4 (the helium isotope) – also called the alpha particle, which carries 1/5 (3.5 MeV) of the total fusion energy in the form of kinetic energy, and a neutron, which carries 4/5 (14.1 MeV). Don’t be alarmed by the alpha particle, the particles are not dangerous in themselves, it is only because of the high speeds at which they are ejected from the nuclei that make them dangerous, but unlike beta or gamma radiation, they are stopped by a piece of paper.

xysciences:

A gif representing nuclear fusion and how it creates energy. 

[Click for more interesting science facts and gifs]

For those who don’t understand the GIF. It illustrates the Deuterium-Tritium fusion; a deuterium and tritium combine to form a helium-4. Most of the energy released is in the form of the high-energy neutron.

Nuclear fusion has the potential to generate power without the radioactive waste of nuclear fission (energy from splitting heavy atoms  into smaller atoms), but that depends on which atoms you decide to fuse. Hydrogen has three naturally occurring isotopes, sometimes denoted ¹H, ²H, and ³H. Deuterium (²H) - Tritium (³H) fusion (pictured above) appears to be the best and most effective way to produce energy. Atoms that have the same number of protons, but different numbers of neutrons are called isotopes (adding a proton makes a new element, but adding a neutron makes an isotope of the same atom). 

The three most stable isotopes of hydrogen: protium (no neutrons, just one proton, hence the name), deuterium (deuterium comes from the Greek word deuteros, which means “second”, this is in reference two the two particles, a proton and a neutron), and tritium (the name of this comes from the Greek word “tritos” meaning “third”, because guess what, it contains one proton and two neutrons). Here’s a diagram

Deuterium is abundant, it can be extracted from seawater, but tritium is a  radioactive isotope and must be either derived(bred) from lithium or obtained in the operation of the deuterium cycle. Tritium is also produced naturally in the upper atmosphere when cosmic rays strike nitrogen molecules in the air, but that’s extremely rare. It’s also a by product in reactors producing electricity (Fukushima Daiichi Nuclear Power Plant). Tritium is a low energy beta emitter (unable to penetrate the outer dead layer of human skin), it has a relatively long half life and short biological half life. It is not dangerous externally, however emissions from inhaled or ingested beta particle emitters pose a significant health risk.

During fusion (energy from combining light elements to form heavier ones), two atomic nuclei of the hydrogen isotopes deuterium and tritium must be brought so close together that they fuse in spite of the strongly repulsive electrostatic forces between the positively charged nuclei. So, in order to accomplish nuclear fusion, the two nuclei must first overcome the electric repulsion (coulomb barrier ) to get close enough for the attractive nuclear strong force (force that binds protons and neutrons together in atomic nuclei) to take over to fuse the particles. The D-T reaction is the easiest to bring about, it has the lowest energy requirement compared to energy release. The reaction products are helium-4 (the helium isotope) – also called the alpha particle, which carries 1/5 (3.5 MeV) of the total fusion energy in the form of kinetic energy, and a neutron, which carries 4/5 (14.1 MeV). Don’t be alarmed by the alpha particle, the particles are not dangerous in themselves, it is only because of the high speeds at which they are ejected from the nuclei that make them dangerous, but unlike beta or gamma radiation, they are stopped by a piece of paper.

mashable:

45 years ago today, Apollo 11 landed on the first humans on the moon. Neil Armstrong and Buzz Aldrin spent 21.5 hours on the lunar surface.

mashable:

45 years ago today, Apollo 11 landed on the first humans on the moon. Neil Armstrong and Buzz Aldrin spent 21.5 hours on the lunar surface.

Stereoscopic View of the Lunar Surface

Apollo 11 carried a number of cameras for collecting data and recording various aspects of the mission, including a 35-mm surface close-up stereoscopic camera. It was designed for the highest possible resolution of a 3-inch square area with a flash illumination and fixed distance. Photography was accomplished by holding the camera on a walking stick against the object to be photographed. The camera was powered by four nickel-cadmium batteries that operated the motor-drive mechanism and an electronic flash strobe light.

There are many details seen in these pictures that were not known previously or that could not be seen with similar definition by astronauts Armstrong and Aldrin in their careful inspection of the lunar surface. The photographs taken on the mission with the close-up stereoscopic camera are of outstanding quality and show in detail the nature of the lunar surface material. From the photographs, information can be derived about the small-scale lunar surface geologic features and about processes occurring on the surface.

Image Credit: John Lloyd/NASA

July 20, 1969: One Giant Leap For Mankind

Astronaut Buzz Aldrin descending the ladder and stepping onto the Moon.  Neil Armstrong's “one small step” onto the lunar surface was actually a 3-foot jump down off the lunar module’s ladder to the ground.

Credit: NASA

July 20, 1969: One Giant Leap For Mankind

Astronaut Buzz Aldrin descending the ladder and stepping onto the Moon.  Neil Armstrong's “one small step” onto the lunar surface was actually a 3-foot jump down off the lunar module’s ladder to the ground.

Credit: NASA

nucleargearing:

Atlas D ICBM Launch
Vandenberg AFB, CA
c. 1960

nucleargearing:

Atlas D ICBM Launch

Vandenberg AFB, CA

c. 1960

amnhnyc:

Astronomers have long pondered the origins of enormous elliptical galaxies in the young Universe. An object 11 billion light-years away spotted by the Herschel mission may help unravel the mystery. 
Two massive spiral galaxies merged to create a giant elliptical galaxy, which were previously believed to form through the absorption of dwarf galaxies over time. 
Learn more about this finding in a Science Bulletin video. 

amnhnyc:

Astronomers have long pondered the origins of enormous elliptical galaxies in the young Universe. An object 11 billion light-years away spotted by the Herschel mission may help unravel the mystery. 

Two massive spiral galaxies merged to create a giant elliptical galaxy, which were previously believed to form through the absorption of dwarf galaxies over time. 

Learn more about this finding in a Science Bulletin video

Fundamental Studies in Droplet Combustion and FLame EXtinguishment in Microgravity (FLEX-2)

The Flame Extinguishment - 2 (FLEX-2) experiment is the second experiment to fly on the ISS which uses small droplets of fuel to study the special spherical characteristics of burning fuel droplets in space. The FLEX-2 experiment studies how quickly fuel burns, the conditions required for soot to form, and how mixtures of fuels evaporate before burning. Understanding how fuels burn in microgravity could improve the efficiency of fuel mixtures used for interplanetary missions by reducing cost and weight. It could also lead to improved safety measures for manned spacecraft.

  • More information: here

Credit: Reid Wiseman/NASA

(Source: youtube.com)

Tokamaks: the future of fusion energy

Fusion is the energy that powers our Sun and other stars.  It has been a goal of scientists around the world to harness this process by which the stars “burn” hydrogen into helium (i.e. nuclear fusion) for energy production on Earth since it was discovered in the 1940′s.

Nuclear fusion is the process by which light nuclei fuse together to create a single, heavier nucleus and release energy.  Given the correct conditions (such as those found in plasma), nuclei of light elements can smash into each other with enough energy to undergo fusion. The “easiest” (most energetically favorable) fusion reaction occurs between the hydrogen isotopes deuterium and tritium.  When the nucleus of a deuterium atom crashes into the nucleus of a tritium atom with sufficient energy, a fusion reaction occurs and a huge amount of energy is released, 17.6 million electron volts to be exact. 

Why fusion? To put this in terms of energy that we all experience; fusion generates more energy per reaction than any other energy source.  A single gram of deuterium/tritium fusion fuel can generate 350 million kJ of energy, nearly 10 million times more energy than from the same amount of fossil fuel!

Fusion power has the potential to provide sufficient energy to satisfy mounting demand, and to do so sustainably, with a relatively small impact on the environment. Nuclear fusion has many potential attractions. Firstly, its hydrogen isotope fuels are relatively abundant – one of the necessary isotopes, deuterium, can be extracted from seawater, while the other fuel, tritium, would be bred from a lithium blanket using neutrons produced in the fusion reaction itself. Furthermore, a fusion reactor would produce virtually no CO2 or atmospheric pollutants, and its other radioactive waste products would be very short-lived compared to those produced by conventional nuclear reactors.

Fusion reactions require so much energy that they must occur with the hydrogen isotopes in this plasma state. Plasma makes up all of the stars, and is the most common form of matter in the visible universe. Since plasmas are made of charged particles every particle can interact with every other particle, even over very long distances. The fact that 99% of the universe is made of plasmas makes studying them very important if we are to understand how the universe works.

How do we create fusion in a laboratory? This is where tokamaks come in. In order for nuclear fusion to occur, the nuclei inside of the plasma must first be extremely hot, like in a star. Unfortunately, no material on Earth can withstand these temperatures so in order to contain a plasma with such high temperatures, we have to be creative. One clever solution is to create a magnetic “bottle” using large magnet coils to capture the plasma and suspend it away from the container’s surfaces. The plasma follows along the magnetic field, suspended away from the walls. This complex combination of magnets used to confine the plasma and the chamber where the plasma is held is known as a tokamak. Tokamaks have a toroidal shape (i.e. they are shaped like a donut) so they have no open ends for plasma to escape. Tokamaks, like the ASDEX Upgrade (pictured above), create and contain the hottest materials in the solar system. The aim of ASDEX Upgrade, the “Axially Symmetric Divertor Experiment”, is to prepare the physics base for ITER.

ITER (International Thermonuclear Experimental Reactor and Latin for “the way” or “the road”) is an international nuclear fusion research and engineering project, which is currently building the world’s largest experimental tokamak nuclear fusion reactor. The ITER project aims to make the long-awaited transition from experimental studies of plasma physics to full-scale electricity-producing fusion power plants.

Further readings:

One Special Day in the Life of Planet Earth

The cameras on NASA’s Cassini spacecraft captured this rare look at Earth and its moon from Saturn orbit on July 19, 2013. Taken while performing a large wide-angle mosaic of the entire Saturn ring system, narrow-angle camera images were deliberately inserted into the sequence in order to image Earth and its moon. This is the second time that Cassini has imaged Earth from within Saturn’s shadow, and only the third time ever that our planet has been imaged from the outer solar system.

Earth is the blue point of light on the left; the moon is fainter, white, and on the right. Both are seen here through the faint, diffuse E ring of Saturn. Earth was brighter than the estimated brightness used to calculate the narrow-angle camera exposure times. Hence, information derived from the wide-angle camera images was used to process this color composite.

Both Earth and the moon have been increased in brightness for easy visibility; in addition, brightness of the Moon has been increased relative to the Earth, and the brightness of the E ring has been increased as well.

The first image of Earth captured from the outer solar system was taken by NASA’s Voyager 1 in 1990 and famously titled “Pale Blue Dot”. Sixteen years later, in 2006, Cassini imaged the Earth in the stunning and unique mosaic of Saturn called “In Saturn’s Shadow-The Pale Blue Dot”. And, seven years further along, Cassini did it again in a coordinated event that became the first time that Earth’s inhabitants knew in advance that they were being imaged from nearly a billion miles (nearly 1.5 billion kilometers) away. It was the also the first time that Cassini’s highest-resolution camera was employed so that Earth and its moon could be captured as two distinct targets.

Credit: NASA/JPL-Caltech/SSI

Titan’s Atmosphere

Titan is the largest moon of Saturn. It is the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found

Titan is primarily composed of water ice and rocky material. Much as with Venus prior to the Space Age, the dense, opaque atmosphere prevented understanding of Titan’s surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in Titan’s polar regions.

The atmosphere is largely nitrogen; minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. Titan’s lower gravity means that its atmosphere is far more extended than Earth’s and about 1.19 times as massive. It supports opaque haze layers that block most visible light from the Sun and other sources and renders Titan’s surface features obscure. Atmospheric methane creates a greenhouse effect on Titan’s surface, without which Titan would be far colder. Conversely, haze in Titan’s atmosphere contributes to an anti-greenhouse effect by reflecting sunlight back into space, cancelling a portion of the greenhouse effect warming and making its surface significantly colder than its upper atmosphere.

Titan’s clouds, probably composed of methane, ethane or other simple organics, are scattered and variable, punctuating the overall haze.The findings of the Huygens probe indicate that Titan’s atmosphere periodically rains liquid methane and other organic compounds onto its surface. Clouds typically cover 1% of Titan’s disk, though outburst events have been observed in which the cloud cover rapidly expands to as much as 8%. One hypothesis asserts that the southern clouds are formed when heightened levels of sunlight during the southern summer generate uplift in the atmosphere, resulting in convection. This explanation is complicated by the fact that cloud formation has been observed not only after the southern summer solstice but also during mid-spring.

Image Credit: NASA/JPL/Space Science Institute

s-c-i-guy:


Perihelion and Aphelion
The closest point to the Sun in a planet’s orbit is called perihelion. The furthest point is called aphelion. Notice how the planet moves fastest at perihelion and slowest at aphelion.
The time during the year that aphelion and perihelion (when we are closet to the sun) changes over a roughly 100,000 year cycle, known as the Milankovitch Cycle.  Our orbit around the sun is not a circle, it is an ellipse with an eccentricity of about 0.0167.  This orbit both changes shape and rotates around the sun much like a spirogram tracing out a flower-like shape.It is summer in the northern hemisphere, a time when people often say things like, “We are closer to the sun than we are in winter.”  This is not really true.  Summer is a product of the angle at which Earth is tilted, right now Earth is tilted so that the northern regions lean toward the sun.  In terms of orbit we are actually at the furthest point Earth gets from the sun.This has interesting implications in terms of the global climate.  This means that right now winters tend to be warm (the planet is closer to the sun) and summers cool (the planet further from the sun).  In the big picture this places us in the midst of a global cool cycle, the type of situation that tends to lead to ice ages, like the one we are emerging from.
source

s-c-i-guy:

Perihelion and Aphelion

The closest point to the Sun in a planet’s orbit is called perihelion. The furthest point is called aphelion. Notice how the planet moves fastest at perihelion and slowest at aphelion.

The time during the year that aphelion and perihelion (when we are closet to the sun) changes over a roughly 100,000 year cycle, known as the Milankovitch Cycle.  Our orbit around the sun is not a circle, it is an ellipse with an eccentricity of about 0.0167.  This orbit both changes shape and rotates around the sun much like a spirogram tracing out a flower-like shape.

It is summer in the northern hemisphere, a time when people often say things like, “We are closer to the sun than we are in winter.”  This is not really true.  Summer is a product of the angle at which Earth is tilted, right now Earth is tilted so that the northern regions lean toward the sun.  In terms of orbit we are actually at the furthest point Earth gets from the sun.

This has interesting implications in terms of the global climate.  This means that right now winters tend to be warm (the planet is closer to the sun) and summers cool (the planet further from the sun).  In the big picture this places us in the midst of a global cool cycle, the type of situation that tends to lead to ice ages, like the one we are emerging from.

source

Microwave Induced Plasma

This coaxial microwave plasma source (MPS) generates plasma without using a magnetic field. It works like an inverse luminescent tube excited by microwaves. The coaxial microwave plasma generator consists of a copper rod (antenna) as inner conductor surrounded by quartz tube filled with argon gas, the plasma is the outer conductor. The inside of the tube is at atmospheric pressure whereas the outside is at low pressure. The plasma formed around the quartz tube acts as an outer conductor in such a way that a spatially extended surface wave is created, just in an equivalent (‘inverse’) situation to that found in the Surfatron source (where the plasma is inside the tube instead of outside).
The microwave with a frequency of 2.45 GHz generated by two magnetrons is fed into the copper rods at both ends. On the outside of the tube, in the low pressure, the microwave fields ignite the plasma. The plasma represents a conductive medium so by increasing microwave power the plasma grows from both ends along the tube, and a homogeneous plasma is formed. The high power microwave breakdown at atmospheric pressure leads to the formation of filamentary structures. These striations or string-like structures, also known as birkeland currents, are seen in many plasmas, like the plasma ball, the aurora,lightning,electric arcs, solar flares, and even supernova remnants.

Microwave Induced Plasma

This coaxial microwave plasma source (MPS) generates plasma without using a magnetic field. It works like an inverse luminescent tube excited by microwaves. The coaxial microwave plasma generator consists of a copper rod (antenna) as inner conductor surrounded by quartz tube filled with argon gas, the plasma is the outer conductor. The inside of the tube is at atmospheric pressure whereas the outside is at low pressure. The plasma formed around the quartz tube acts as an outer conductor in such a way that a spatially extended surface wave is created, just in an equivalent (‘inverse’) situation to that found in the Surfatron source (where the plasma is inside the tube instead of outside).

The microwave with a frequency of 2.45 GHz generated by two magnetrons is fed into the copper rods at both ends. On the outside of the tube, in the low pressure, the microwave fields ignite the plasma. The plasma represents a conductive medium so by increasing microwave power the plasma grows from both ends along the tube, and a homogeneous plasma is formed. The high power microwave breakdown at atmospheric pressure leads to the formation of filamentary structures. These striations or string-like structures, also known as birkeland currents, are seen in many plasmas, like the plasma ball, the aurora,lightning,electric arcs, solar flares, and even supernova remnants.

Saturn’s Rings and Enceladus

Saturn’s most distinctive feature is the thousands of rings that orbit the planet. Despite the fact that the rings look like continuous hoops of matter encircling the giant planet, each ring is actually made of tiny individual particles. Saturn’s rings consist largely of water ice mixed with smaller amounts of dust and rocky matter. Data from the Cassini spacecraft indicate that the environment around the rings is like an atmosphere, composed principally of molecular oxygen.

The ring system is divided into 5 major components: the G, F, A, B, and C rings, listed from outside to inside (but in reality, these major divisions are subdivided into thousands of individual ringlets). The F and G rings are thin and difficult to see, while the A, B, and C rings are broad and easily visible. The large gap between the A ring and and the B ring is called the Cassini division. One of Saturn’s moons, namely; Enceladus is the source of Saturn’s E-ring. The moon’s geyser-like jets create a gigantic halo of ice, dust, and gas that helps feed Saturn’s E ring.

Enceladus has a profound effect on Saturn and its environment. It’s the only moon in our solar system known to substantially influence the chemical composition of its parent planet. The whole magnetic environment of Saturn is weighed down by the material spewing from Enceladus, which becomes plasma — a gas of electrically charged particles.  This plasma, which creates a donut-shaped cloud around Saturn, is then snatched by Saturn’s A-ring, which acts like a giant sponge where the plasma is absorbed. 

Credit: , NASA/JPL/SSI

christinetheastrophysicist:

A few days ago, we found out that comet 67P/Churyumov–Gerasimenko is a contact binary. Now we have rotating view of it. This gif uses 36 images each separated by 20 minutes to show a 360° view of the comet. It takes the comet 12.4 hours to complete one rotation.
Read more about the comet on the Rosetta Blog.

christinetheastrophysicist:

A few days ago, we found out that comet 67P/Churyumov–Gerasimenko is a contact binary. Now we have rotating view of it. This gif uses 36 images each separated by 20 minutes to show a 360° view of the comet. It takes the comet 12.4 hours to complete one rotation.

Read more about the comet on the Rosetta Blog.