Guide to Space Archives

April 3, 2011December 24, 2015 by Tega Jessa

How Does Fog Form?

Fog is a natural weather conditions that can cause visibility to become zero. It can cause accidents on normally safe roads and is such a serious weather condition that schools delay the start of the day until the sun burns it off. So how does fog form? First it is important to understand that fog is basically a cloud on the ground. This means like clouds it is a collection of tiny water droplets formed when evaporated water is cooled. The way it is cooled determines how fog is formed.

The first way that fog is formed is by infrared cooling. Infrared cooling happens due to the change of seasons from summer to fall and winter. During the summer the ground absorbs solar radiation. As air passes over it is made warm and moist. When the seasons change this mass of warm moist air collides with the cooler that is now prevalent. This cause is the water vapor in the air mass to condense quickly and fog is formed. This fog is often called radiation fog due to the way it forms. This kind is the most common type of fog. It also happens when an unseasonable day of warm weather combined with high humidity is followed by dropping temperatures

The next way that fog forms is through advection. Advection is wind driven fog formation. In this case warm air is pushed by winds across a cool surface where it condenses into fog. There are also other kinds of fog like hail fog or freezing fog. Each of these conditions is where condensed water droplets are cooled to the point of freezing. There is also fog formed over bodies of water. One type is sea smoke. This is a type of fog that forms when cool air passes over a warm body of water or moist land.

In general we see that fog is formed whenever there is a temperature difference between the ground and the air. When the humidity is high enough and there is enough water vapor or moisture fog is sure to form. However the kind of fog and how long is last and its effects will depends on the different conditions mentioned. One interesting kind of fog actually helps to make snow melt faster.

We have written many related articles for Universe Today. Here’s an article about stratus clouds, and here’s an article about acid rain.

If you’d like more info on fog, check out NOAA National Weather Service website. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Reference:
http://www.crh.noaa.gov/jkl/?n=fog_types

March 26, 2011April 26, 2016 by Matt Williams

Southern Cross Constellation

[/caption]For the lucky residents of the Southern Hemisphere, or those fortunate enough to enjoy a vacation in Hawaii or Cancun, there’s a stellar delight that few Northerners know about. It’s called the Southern Cross, a small but beautiful constellation located in the southern sky, very close to the neighboring constellation of Centaurus. Originally known by the Latin name Crux, which is due to its cross shape, this constellation is one of the easiest to identify in the night sky. For centuries, it has served as a navigational beacon for sailors, an important symbol to the Egyptians, and played an important role in the spiritual beliefs of the Aborigines and many other cultures in the Southern Hemisphere.

The first recorded example of Crux’s discovery was around 1000 BC during the time of the Ancient Greeks. At the latitude of Athens, Crux was clearly visible, though low in the night sky. At the time, the Greeks identified it as being part of the constellation Centaurus. However, the precession of the equinoxes gradually lowered its stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. Crux fell into anonymity for northerners until the Age of Discovery (from the early 15th to early 17th centuries) when it was rediscovered by Europeans. The first to do so were the Portuguese, who mapped it for navigation uses while rounding the southern tip of Africa. During this time, Crux was also separated from Centaurus, though it is not altogether clear who was responsible. Some attribute it to the French astronomer Augustin Royer who did it in 1679 while others believe it was Dutch astronomer PetrusPlancius who did the deed in 1613. Regardless, it is believed to have taken place in the 17th century, placing it within the context of European expansion and the revolution that was taking place in the sciences at the time.

In terms of cultural significance, the Crux, like all constellations, played an important role in the belief system of many cultures. In the ancient mountaintop village of Machu Picchu, a stone engraving exists which depicts the constellation. In addition, in Quechua (the language of the Incas) Crux is known as “Chakana”, which literally means “stair”, and holds deep symbolic value in Incan mysticism (the cross represented the three tiers of the world: the underworld, world of the living, and the heavens). To the Aborigines and the Maori, Crux is representative of animist spirits who play a central role in their ancestral beliefs. To the ancient Egyptians, Crux was the place where the Sun Goddess Horus was crucified, and marked the passage of the winter season. The Southern Cross is also featured prominently on the flags of several southern nations, including Australia, Brazil, New Zealand, Papua New Guinea, and Samoa.

We have written many articles about the Southern Cross constellation for Universe Today. Here’s an article about Crux, and here’s an article about constellations.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We’ve done many episodes of Astronomy Cast about stars. Listen here, Episode 12: Where Do Baby Stars Come From?

References:
http://en.wikipedia.org/wiki/Crux
http://en.wikipedia.org/wiki/Age_of_Discovery
http://library.thinkquest.org/C005462/scross.html
http://www.windows2universe.org/the_universe/crux.html
http://www.ancientworlds.net/aw/Article/941062

March 26, 2011December 24, 2015 by Matt Williams

Radioisotope

[/caption]
It was just over a century ago that a little known French scientist named Henri Becquerel came across something new and immensely startling. At the time, while working with phosphorescent materials (i.e. materials that glow in the dark after being subjected to light), he discovered naturally occurring rays that he couldn’t account for. In time, these rays were discovered to be present in several naturally occurring elements, and were dubbed radioactivity. Those metals that exhibited them also came to be known as Radioactive Isotopes.

Radioisotopes, (also known as radioactive isotopes or radionuclides), are atoms with a different number of neutrons than a usual atom. Due to this imbalance, these isotopes have an unstable nucleus that decays, and in the process emitting alpha, beta and gamma rays until the isotope reaches stability. Once it’s stable, the isotope has transformed into another element entirely. Every chemical element has one or more radioisotopes, with over 1,000 isotopes accounted for in total. Approximately 50 of these are found in nature; the rest are produced artificially as the direct result of nuclear reactions or indirectly as the radioactive descendants of these products.

Of the naturally occurring radioisotopes, there are three categories that are used to group them. The first is primordial radionuclides, which originate mainly within the interior of stars and like uranium and thorium, are still present because their half-lives are so long that they have not yet completely decayed. The second group, secondary radionuclides, are radiogenic isotopes derived from the decay of primordial radionuclides and are characterized by their shorter half-lives. The third and final group is known cosmogenic radionuclides, which consists of isotopes like Carbon 14 which are constantly produced in the atmosphere due to cosmic rays. Artificially produced radionuclides, on the other hand, are produced by nuclear reactors, particle accelerators or by radionuclide generators (where a parent isotope, usually produced in a nuclear reactor, is allowed to decay to produce a radioisotope). In addition, nuclear explosions are known to produce artificial radioisotopes as well.

Radioisotopes are used today for a variety of purposes. When it comes to the field of nuclear medicine, radioactive isotopes are used in MRI’s and X-rays for diagnostic purposes, for targeted radiation therapy, and to sterilize medical equipment. In biochemistry and genetics, radionuclides are used in molecular and DNA research in order to “label” molecules and trace chemical and physiological processes. Carbon-14, a naturally occurring cosmogenic isotope, is used for carbon dating by archeologists, paleontologists, and geologists. In agriculture, radiation is used to stop the sprouting of root crops, kill parasites and pests, and in veterinary medicine. And when it comes to industry, radionuclides are used to study the rate of wear and corrosion of metals, to test for leaks and seams, analyze pollutants, study the movement of surface water, measure water runoffs from rain and snow, and the flow rates of streams and rivers.

We have written many articles about radioisotopes for Universe Today. Here’s an article about isotopes, and here’s an article about radioactive decay.

If you’d like more info on radioisotopes, check out these articles from NDT Resource Center and Science Courseware.

We’ve also recorded an entire episode of Astronomy Cast all about the Age of the Universe. Listen here, Episode 122: How Old is the Universe?.

References:
http://en.wikipedia.org/wiki/Radionuclide
http://en.wikipedia.org/wiki/Radioactive_decay
http://www.britannica.com/EBchecked/topic/489027/radioactive-isotope
http://en.wikipedia.org/wiki/Radiocarbon_dating
http://www.ehow.com/about_5095610_radioactive-isotopes.html

March 26, 2011December 24, 2015 by Matt Williams

Law of Inertia

[/caption]In the world of physics, there are few people who have been more influential than Sir Isaac Newton. In addition to his contributions to astronomy, mathematics, and empirical philosophy, he is also the man who pioneered classical physics with his laws of motion. Of these, the first, otherwise known as the Law of Inertia, is the most famous and arguably the most important. In the language of science, this law states that: Every body remains in a state of constant velocity unless acted upon by an external unbalanced force. This means that in the absence of a non-zero net force, the center of mass of a body either remains at rest, or moves at a constant velocity. Put simply, it states that a body will remain at rest or in motion unless acted upon by an external and unbalanced force.

Prior to Aristotle’s theories on inertia, the most generally accepted theory of motion was based on Aristotelian philosophy. This ancient theory stated that, in the absence of an external motivating power, all objects on Earth would come to rest and that moving objects only continue to move so long as long there is a power inducing them to do so. In a void, no motion would be possible since Aristotle’s theory claimed that the motion of objects was dependent on the surrounding medium, that it was responsible for moving the object forward in some way. By the Renaissance, however, this theory was coming to be rejected as scientists began to postulate that both air resistance and the weight of an object would play a role in arresting the motion of that object.

Further advances in astronomy were another nail in this coffin. The Aristotelian division of motion into “mundane” and “celestial” became increasingly problematic in the face of Copernicus’ model in the 16th century, who argued that the earth (and everything on it) was in fact never “at rest”, but was actually in constant motion around the sun.Galileo, in his further development of the Copernican model, recognized these problems and would later go on to conclude that based on this initial premise of inertia, it is impossible to tell the difference between a moving object and a stationary one without some outside point of comparison.

Thus, though Newton was not the first to express the concept of inertia, he would later refine and codify them as the first law of motion in his seminal work PhilosophiaeNaturalis Principia Mathematica (Mathematical Principals of Natural Philosophy) in 1687, in which he stated that: unless acted upon by a net unbalanced force, an object will maintain a constant velocity. Interestingly enough, the term “interia” was not used in the study. It was in fact JohanneKepler who first used it in his Epitome AstronomiaeCopernicanae (Epitome of Copernican Astronomy) published from 1618–1621. Nevertheless, the term would later come to be used and Newton recognized as being the man most directly responsible for its articulation as a theory.

We have written many articles about the law of inertia for Universe Today. Here’s an article about Newton’s Laws of Motion, and here’s an article about Newton’s first law.

If you’d like more info on the law of inertia, check out these articles from How Stuff Works and NASA.

We’ve also recorded an entire episode of Astronomy Cast all about Gravity. Listen here, Episode 102: Gravity.

References:
http://en.wikipedia.org/wiki/Inertia
http://en.wikipedia.org/wiki/Isaac_Newton
http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion
http://science.howstuffworks.com/science-vs-myth/everyday-myths/newton-law-of-motion1.htm

March 26, 2011April 26, 2016 by Matt Williams

Emissivity of Materials

[/caption]In the last few centuries, in which time we have had several scientific revolutions, our understanding of heat, energy and the exchange thereof has grown exponentially. In particular has been the increasing ability to gauge the amounts of energy involved in particular processes and in turn create theoretical frameworks, units, and even tools with which to measure them. One such concept is the measurement known as Emissivity. Essentially, this is the relative ability of a material’s surface (usually written ? or e) to emit energy as radiation. It is expressed as the ratio of the emissivity of the material in question to the radiation emitted by a blackbody (an idealized physical body that absorbs all incident electromagnetic radiation) at the same temperature. This means that while a true black body would have an emissivity value of 1 (? = 1), any other object, known as a “grey body”, would have an emissivity value of less than 1 (? < 1). In general, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Emissivity also depends on such factors as temperature, emission angle, and wavelength of the radiation. At the opposite end of the spectrum is the material’s absorptivity (or absorptance), which is the measure of radiation absorbed by a material at a particular wavelength. When dealing with non-black surfaces, the relative emissivity follows Kirchhoff's law of thermal radiation which states that emissivity is equal to absorptivity. Essentially an object that does not absorb all incident light will also emit less radiation than an ideal black body. An important function for emissivity has to do with the Earth’s atmosphere. Like all other “grey bodies”, the Earth’s atmosphere is able to absorb and emit radiation. The overall emissivity of Earth's atmosphere varies according to cloud cover and the concentration of gases that absorb and emit energy in the thermal infrared (i.e. heat energy). In this way, and by using the same criteria by which they are able to calculate the emissivity of “grey bodies”, scientists are able to calculate the amount of thermal radiation emitted by the atmosphere, thereby gaining a better understanding of the Greenhouse Effect. Every known material has an emissivity coefficient. Those that have a higher coefficient tend to be polished metals, such as aluminum and anodized metals. However, certain materials that are not metals and are non-reflective, such as red bricks, asbestos, concrete and pressed carbon, have equally high coefficients. In addition, naturally occurring materials such as ice, marble, and lime also have high emissivity coefficients. We have written many articles about emissivity of materials for Universe Today. Here's an article about heat rejection systems, and here's an article about absorptivity. If you'd like more info on emissivity, check out these articles from Engineering Toolbox and Science World.

We’ve also recorded an entire episode of Astronomy Cast all about Electromagnetism. Listen here, Episode 103: Electromagnetism.

References:
http://en.wikipedia.org/wiki/Emissivity
http://en.wikipedia.org/wiki/Absorptance
http://en.wikipedia.org/wiki/Black_body
http://www.thefreedictionary.com/emissivity
http://www.monarchserver.com/TableofEmissivity.pdf

March 19, 2011December 24, 2015 by Tega Jessa

Permanent Magnet

[/caption]
A permanent magnet is a magnet that does not lose its magnet field. However what makes a magnet permanent? In order to understand this we need to know how magnets work. Magnetism is an aspect of the phenomenon known as the electromagnetic force a fundamental force of the physical universe. Magnetism like its other aspect electricity manifests itself as a field. What makes a magnet is when certain substances and elements are induced with a strong magnetic field. In the case of permanent magnets this field remains over time without weakening.

A permanent magnet is a magnet because of the orientation of its domains. Domains are the small magnetic field inherent in the crystalline structure of ferromagnetic materials. Ferromagnetic materials are the only substances capable of being made into magnets they are normally iron, nickel, or alloys that are made or rare-earth metals. A magnet is created when certain condition cause separate domains in a ferromagnetic item to be all aligned in the same direction. However the method used in most cases weak magnets can only be made. This is normally by direct contact with a naturally magnetic material or by running an electric current through it. However in the case of a field produced by rubbing it against a strong magnet is too weak and will fade over time as the domains return to their original positions.

The main way that permanent magnets are created is by heating a ferromagnetic material to a key high temperature. The temperature is specific to each kind of metal but it has the effect of aligning and “fixing” the domains of the magnet in a permanent position. It is conjectured that this same process inside the Earth is what creates natural permanent magnets.

Permanent magnets are important for their industrial uses especially when it comes to power generation and electric motors. The induction process for turbines and generators needs permanent magnets to turn mechanical motion into energy. They are also important for electric motors in many electronics using the reverse of the induction of electric current to make mechanical energy. As you can see without the permanent magnet we would not be able to take full advantage of the capabilities of electricity in modern devices.

We have written many articles about permanent magnets for Universe Today. Here’s an article about bar magnets, and here’s an article about super magnets.

If you’d like more info on permanent magnets, check out these articles from Hyperphysics and Practical Physics.

We’ve also recorded an entire episode of Astronomy Cast all about Magnetism. Listen here, Episode 42: Magnetism Everywhere.

References:
Hyperphysics
How Magnets Work

March 6, 2011August 19, 2016 by Jerry Coffey

Which Planet Has The Longest Day?

Just to be clear, this answer to ‘which planet has the longest day’ is based on this criteria: a planets day is how long it takes it to complete one rotation on its axis. This is also referred to as its rotational period. So, Venus has the longest day of any planet in our solar system. It completes one rotation every 243 Earth days. Its day lasts longer than its orbit. It orbits the Sun every 224.65 Earth days, so a day is nearly 20 Earth days longer than its year.

Length Of A Day On The Planets In Our Solar System

Mercury: 58 days and 15 hours
Venus: 243 days
Mars: 24 hours, 39 minutes and 35 seconds
Jupiter: 9.9 hours
Saturn: 10 hours 45 minutes 45 seconds, but can only be approximated because of atmospheric density.
Uranus: 17 hours, 14 minutes and 24 seconds
Neptune: 16 hours, 6 minutes and 36 seconds, but it is a bit more complicated than that. The equator and poles rotate at different speeds. You would have to do more research on the planet to fully understand the varying day on Neptune.

Now, back to why the Venusian day is longer than its year. Venus is closer to the Sun; therefore, its orbit takes a shorter period of time than its rotation upon its axis. The planet also rotates in retrograde. That means it spins in the opposite direction of the Earth. If you were standing on Venus, you could see the Sun rise in the West and set in the East.

A manned Venus flyby mission was proposed in the late 1960s. The mission was planned to launch in late October or early November 1973, and would have used a Saturn V rocket to send three men. The flight would have lasted approximately one year. The spacecraft would have passed approximately 5,000 km from the surface about four months into the flight. There have been several unmanned probes and flybys of the planet, including MESSENGER and the Venus Express. Future proposed missions include the BepiColombo, Venus InSitu Explorer, and the Venera-D.

We have written many articles about Venus for Universe Today. Here are some interesting facts about planet Venus, and here are some pictures of planet Venus.

If you’d like more information on Venus, check out Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We’ve also recorded an entire episode of Astronomy Cast all about Venus. Listen here, Episode 50: Venus.

March 6, 2011December 24, 2015 by Jerry Coffey

What Is Mars Atmosphere Made Of

[/caption]I think that one of the most interesting questions that have been posed of late is ‘what is Mar’s atmosphere made of?’ There has been a great deal of study done on this topic and interest is increasing since the discovery of methane, a possible indicator of life.

The atmosphere of Mars is over 95% carbon dioxide, 95.32% to be exact. The breakdown of gases goes like this:

Carbon dioxide 95.32%

Nitrogen 2.7%

Argon 1.6%

Oxygen 0.13%

Carbon monoxide 0.07%

Water vapor 0.03%

Nitric oxide .0013%

Trace gases(including krypton, methane, etc)

The Martian atmosphere has four main layers: lower, middle, upper, and exosphere. The lower atmosphere is a warm region(around 210 K). It is warmed by airborne dust(1.5 micrometers across) and heat radiated from the surface. This airborne dust gives the planet its ruddy brown appearance. The middle atmosphere is features a jetstream similar to Earth’s. The upper atmosphere is heated by the solar wind and the temperatures are much higher than at the surface. This heat separates the gases. The exosphere starts at about 200 km and has no clear end. It just tapers off into space.

The carbon dioxide in the atmosphere freezes for part of the year and may drop to the surface. As much as 25% of the atmospheric carbon dioxide condenses at the polar caps into solid ice(dry ice) because the Martian poles are not exposed to sunlight during the planet’s winter. When the poles are again exposed to sunlight, the ice returns to its gas form and rises back into the atmosphere. So, a significant annual variation in the atmospheric pressure and atmospheric composition around the Martian poles.

The methane mentioned earlier is used to show the possibility of life on Mars. While it is a byproduct of life, it is also a result of volcanism, geothermal process, and hydrothermal activity. Methane is an unstable gas, so there has to be a source on the planet that is constantly replenishing it. It has to be a very active source, because studies have shown that the methane is destroyed in less than on Earth year. It is thought that peroxides and perchlorates in the soil or that it condenses and evaporates seasonally from clathrates.

Now you answer ‘ what is Mar’s atmosphere made of?’ the next time it comes up. You can be sure that the methane component will continue to be studied by rovers, orbiters, and, in the future, astronauts.

We have written many articles about the atmosphere of Mars for Universe Today. Here’s an article about the air on Mars, and here’s an article about Mars’ comparison with Earth.

If you’d like more info on Mars, check out Hubblesite’s News Releases about Mars, and here’s a link to the NASA Mars Exploration home page.

We’ve also recorded an episode of Astronomy Cast all about Mars. Listen here, Episode 52: Mars.

Reference:
NASA Mars Fact Sheet

February 24, 2011April 26, 2016 by Matt Williams

Tachyon

[/caption]Ever since Einstein unveiled his theory of relativity, the speed of light has been considered to be the physical constant of the universe, interrelating space and time. In short, it was the speed at which light and all other forms of electromagnetic radiation were believed to travel at all times in empty space, regardless of the motion of the source or the inertial frame of reference of the observer. But suppose for a second that there was a particle that defied this law, that could exist within the framework of a relativistic universe, but at the same time defy the foundations on which its built? Sounds impossible, but the existence of such a particle may very well be necessary from a quantum standpoint, resolving key issues that arise in that chaotic theory. It is known as the Tachyon Particle, a hypothetical subatomic particle that can move faster than light and poses a number intriguing problems and possibilities to the field of physics.

In the language of special relativity, a tachyon would be a particle with space-like four-momentum and imaginary proper time. Their existence was first attributed to German physicist Arnold Sommerfeld; even though it was Gerald Feinberg who first coined the term in the 1960s, and several other scientists helped to advance the theoretical framework within which tachyons were believed to exist. They were originally proposed within the framework of quantum field theory as a way of explaining the instability of the system, but have nevertheless posed problems for the theory of special relativity.

For example, if tachyons were conventional, localizable particles that could be used to send signals faster than light, this would lead to violations of causality in special relativity. But in the framework of quantum field theory, tachyons are understood as signifying an instability of the system and treated using a theory known as tachyon condensation, a process that attempts to resolve their existence by explaining them in terms of better understood phenomena, rather than as real faster-than-light particles. Tachyonic fields have appeared theoretically in a variety of contexts, such as the bosonic string theory. In general, string theory states that what we see as “particles” —electrons, photons, gravitons and so forth—are actually different vibrational states of the same underlying string. In this framework, a tachyon would appear as either indication of instability in the D-brane system or within spacetime itself.

Despite the theoretical arguments against the existence of tachyon particles, experimental searches have been conducted to test the assumption against their existence; however, no experimental evidence for the existence of tachyon particles has been found.

We have written many articles about tachyon for Universe Today. Here’s an article about elementary particles, and here’s an article about Einstein’s Theory of Relativity.

If you’d like more info on tachyon, check out these articles from Science World. Also, you may want to browse through a forum discussion about tachyons.

We’ve also recorded an entire episode of Astronomy Cast all about the Theory of Special Relativity. Listen here, Episode 9: Einstein’s Theory of Special Relativity.

Sources:
http://en.wikipedia.org/wiki/Tachyon
http://en.wikipedia.org/wiki/Speed_of_light
http://scienceworld.wolfram.com/physics/Tachyon.html
http://en.wikipedia.org/wiki/D-brane
http://www.nasa.gov/centers/glenn/technology/warp/warp.html

February 24, 2011December 24, 2015 by Matt Williams

Plasma

All About Electromagnetic Radiation — The Sun emits electromagnetic radiation

[/caption]
Anyone who took elementary science in grade school recalls the lesson about the three states of matter, right? That was the one where we were told that matter comes in three basic forms: liquid, solid and gas. This works for the periodic table of elements and can be extended to include just about any compound. Except perhaps for whipped cream (that damnable compound continues to defy attempts as classification!) But what if there were a fourth state for matter? It occurs when a state of matter similar to gas contains a large portion of ionized particles and generates its own magnetic field. It’s called Plasma, and it just happens to be the most common type of matter, comprising more than ninety-nine percent of matter in the visible universe and which permeates the solar system, interstellar and intergalactic environments.

The basic premise behind plasma is that heating a gas dissociates its molecular bonds, rendering it into its constituent atoms. Further heating leads to ionization (a loss of electrons), which turns it into a plasma. This plasma is therefore defined by the existence of charged particles, both positive ions and negative electrons.The presence of a large number of charged particles makes the plasma electrically conductive so that it responds strongly to electromagnetic fields. Plasma, therefore, has properties quite unlike those of solids, liquids, or gases and is considered a distinct state of matter. Like a gas, plasma does not have a definite shape or a definite volume unless enclosed in a container. But unlike gas, under the influence of a magnetic field, it may form structures such as filaments, beams and double layers. It is precisely for this reason that plasma is used in the construction of electronics, such as plasma TVs and neon signs.

The existence of plasma was first discovered by Sir William Crookes in 1879 using an assembly that is today known as a “Crookes tube”, an experimental electrical discharge tube in which air is ionized by the application of a high voltage through a voltage coil. At the time, he labeled it “radiant matter” because of its luminous quality. Sir J.J. Thomson, a British physicist, identified the nature of the matter in 1897, thanks to his discovery of electrons and numerous experiments using cathode ray tubes. However, it was not until 1928 that the term “plasma” was coined by Irving Langmuir, an American chemist and physicist, who was apparently reminded of blood plasma.

As already mentioned, plasmas are by far the most common phase of matter in the universe. All the stars are made of plasma, and even the space between the stars is filled with a plasma, albeit a very sparse one.

We have written many articles about plasma for Universe Today. Here’s an article about the plasma engine, and here’s an article about the states of matter.

If you’d like more info on plasma, check out these articles from Chem4Kids and NASA Science.

We’ve also recorded an episode of Astronomy Cast all about the Sun. Listen here, Episode 30: The Sun, Spots and All.

Sources:
http://en.wikipedia.org/wiki/Plasma_%28physics%29
http://en.wikipedia.org/wiki/Crookes_tube
http://en.wikipedia.org/wiki/Charge_carrier
http://en.wikipedia.org/wiki/J._J._Thomson
http://en.wikipedia.org/wiki/Irving_Langmuir
http://www.plasmas.org/basics.htm
http://www.plasmas.org/what-are-plasmas.htm