Posted on by Matt Williams

What is Planck Time?

Planck Time
The Universe. So far, no duplicates found@

What is the smallest unit of time you can conceive? A second? A millisecond? Hard to say seeing as how time is relative. Under the right circumstances, hours can fly by and seconds can feel like a lifetime. But unfortunately for physicists, time is not something that can be dealt with so philosophically. And since they deal with cosmological forces both infinitesimally large and small, they need units that can objectively measure them. When it comes to dealing with the small, Planck Time is the measurement of choice. Named after German physicist Max Planck, the founder of quantum theory, a unit of Planck time is the time it takes for light to travel, in a vacuum, a single unit of Planck length. Taken together, they part of the larger system of natural units known as Planck units.

Originally proposed in 1899 by German physicist Max Planck, Planck units are physical units of measurement defined exclusively in terms of five universal physical constants. These are the Gravitational constant (G), the Reduced Planck constant (h), the speed of light in a vacuum (c), the Coulomb constant 1/4??0 (ke or k), and Boltzmann’s constant (kB, sometimes k). Each of these constants can be associated with at least one fundamental physical theory: c with special relativity, G with general relativity and Newtonian gravity, ? with quantum mechanics, ?0 with electrostatics, and kB with statistical mechanics and thermodynamics. They were invented as a means of simplifying the particular algebraic expressions appearing in theoretical physics, especially in quantum mechanics.

Ultimately, Planck time is derived from the field of mathematical physics known as dimensional analysis, which studies units of measurement and physical constants. The Planck time is the unique combination of the gravitational constant G, the relativity constant c, and the quantum constant h, to produce a constant with units of time. They are often semi-humorously referred to by physicists as “God’s units” because eliminate anthropocentric arbitrariness from the system of units, unlike the meter and second, which exist for purely historical reasons and are not derived from nature. Some challenges to Planck’s Time have been mounted. For example, in 2003 during the analysis of the Hubble Space Telescope Deep Field images, some scientists speculated that where there are space-time fluctuations on the Planck scale, images of extremely distant objects should be blurry. The Hubble images, they claimed, were too sharp for this to be the case. Other scientists disagreed with this assumption however, with some saying the fluctuations would be too small to be observable, others saying that the speculated blurring effect that was expected was off by a very large magnitude.

A unit of Planck Time can be expressed as follows:

Planck Time
Planck Time

We have written many articles about Planck Time for Universe Today. Here’s an article about the Big Bang Theory, and here’s an article about astronomical units.

If you’d like more info on the Planck Time, check out Wikipedia, and here’s a link to Physics and Astronomy Online.

We’ve also recorded a Question Show all about Black Hole Time. Listen here, Question Show: Galileoscope, Black Hole and What Exactly is Energy?.

Sources:
http://en.wikipedia.org/wiki/Planck_time
http://en.wikipedia.org/wiki/Max_Planck
http://en.wikipedia.org/wiki/Planck_units
http://scienceworld.wolfram.com/physics/PlanckTime.html
http://en.wikipedia.org/wiki/Dimensional_analysis

Posted on by Matt Williams

North American Plate

All About Plate Tectonics

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Oftentimes when we think of the Earth, we tend to think of stable landmasses that are surrounded by vast oceans. It’s easy for us to forget that the Earth is still very much a work in a progress, that its foundations are mobile slabs of rock, known as plates, which are constantly on the move and shuffling back and forth. In our next of the woods, aka. North American, we inhabit what is appropriately named the North American Plate, the tectonic boundary that covers most of North America, Greenland, Cuba, Bahamas, and parts of Siberia and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. It is composed of two types of lithosphere: the upper crust (where the continental land masses reside) and the thinner oceanic crust.

As one of the Earth’s original continents, the North American Plate started forming some three billion years ago when the planet was much hotter and mantle convection much more vigorous. Roughly two billions years ago, the Earth cooled and these old floating pieces of the lithosphere, called cratons, stopped growing. Since that time, the plates have been moving back and forth across the globe, their cratons colliding to form the continents that we know and recognize today. Beginning in the Cambrian period, over five hundred million years ago, the cratons of Laurentia and Siberia broke off from the main landmass of Pangaea, which thereafter would be known as Gondwana. By the late Mezosoic era (circa two hundred million years ago) the Laurentian and Eurasian cratons combined to form the supercontinent of Laurasia. Since that time, the separation of the North American and Eurasian plates has led to the separation of the North America from Asia. As the North American plate drifted west, the landmasses of Iceland and Greenland broke off in the east while in the west, it collided with the Eurasian plate again, adding the landmass of Siberia to East Asia.

In terms of what makes the plates move across the Earth, a number of theories coexist. One theory is what is known as the “conveyor belt” principle, where the Earth’s lithosphere has a higher strength and lower density than the underlying asthenosphere and lateral density variations in the mantle result in the slow drifting motion of the plates, resulting in collisions and subduction zones. One of the main points of the theory is that the amount of surface of the plates that disappear through subduction along the boundaries where they collide is more or less equal to the new crust that is formed along the margins where they are drifting apart. In this way, the total surface of the Globe remains the same. A different explanation lies in different forces generated by the rotation of the Globe and tidal forces of the Sun and the Moon. A final theory which predates the Plate Tectonics “paradigm”, has it that a gradual shrinking (contraction) or gradual expansion of the Globe is responsible.

We have written many articles about the North American Plate for Universe Today. Here’s an article about the continental plate, and here’s an article about the plate tectonics theory.

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded related episodes of Astronomy Cast about Plate Tectonics. Listen here, Episode 142: Plate Tectonics.

Sources:
http://en.wikipedia.org/wiki/North_American_Plate
http://en.wikipedia.org/wiki/Plate_tectonics
http://www.platetectonics.com/book/page_5.asp
http://www.uwgb.edu/dutchs/GeolColBk/NAmerPlate.HTM
http://en.wikipedia.org/wiki/Mantle_convection
http://en.wikipedia.org/wiki/Craton
http://en.wikipedia.org/wiki/Laurasia

Posted on by Nancy Atkinson

Rover Teams Keeping Spirits Up on Fate of Frozen Mars Rover

A composite image of how the Spirit rover probably looks, stuck in Gusev Crater. Credit: NASA, image editing by Stu Atkinson.

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The hibernating Spirit rover hasn’t communicated with Earth since March 22 of this year, and while everyone hopes for the best, NASA, it seems, wants to brace rover fans for the worst, just in case. The space agency has dutifully issued a couple of press releases the past few months saying it is possible we may not hear from the rover again. Even Cornell University – home of MER PI Steve Squyres — featured an article in their Daily Sun newspaper this week with the headline, “Mars Rover May Have Lost Power for Good.” But yet, Squyres is quoted “Spirit hasn’t died; we haven’t heard from it, but we suspect it is still alive and we are waiting to hear from it.”

So what are Spirit’s chances? And what are the real sentiments of everyone on the rover team –has anyone actually forsaken hope of hearing from the plucky rover that surprised us time and time again? Universe Today checked in with Mars rover driver Scott Maxwell for an update:

“I don’t have the sense that anyone around here has given up on Spirit,” Maxwell said in an email. “The general consensus, I think, is that she’ll wait until a day or so past the last time anyone expects to hear from her, and then pop up with 800 Watt-hours per sol.”

That’s the Spirit rover, for you. Always full of surprises.

And a robotic version of Lazarus rising from the dead wouldn’t be all that astounding. In the past, she has amazed us all by doing things like being able to climb to the top of Husband Hill and shuffle back down again, then continuing to keep on truckin’ even when a wheel gave out – years ago, and lately, she still provided scientific discoveries even while asleep.

The Spirit rover, as seen by the HiRISE camera on the Mars Reconnaissance Orbiter. Credit: NASA, image enhanced by Stu Atkinson.

Even though it seems like ages since we’ve heard from the rover, remember that the Martian winter in Spirit’s location runs through November here on Earth, so it hasn’t even started to really warm up yet.

“There was a long, low-probability period starting about late July or early August when we didn’t expect to hear from her, but we theoretically could have,” Maxwell said. “That probably contributes to the idea that we “should” have heard from her by now — but really, there was just a low, flat, leading edge of the probability curve.”

Back in July, rover engineers began a “sweep and beep” campaign, where instead of just listening, they send commands to the rover to respond back with a communications beep. If the rover is awake and hears the call, she will send back a beep.

But we haven’t heard a beep yet.

The rover is likely in a low-power hibernation mode since it wasn’t able to get to a favorable slope to capture sunlight on its solar panels during its fourth Martian winter. The low angle of sunlight during these months limits the power able to be generated. During hibernation, the rover shuts down communications and other activities so available energy can be used to recharge and heat the batteries, and to keep the mission clock running.

Maxwell said their models say the solar power at Gusev Crater should just now be getting good enough that Spirit could have multiple wakeups per sol. “Theoretically we have a shot at getting our “beep” sequence in on any of those wakeups,” he said. “It’s still the case that any individual wakeup presents us only with a low-probability chance of hearing from her, we just potentially get more of those chances per unit of time.”

It is kind a crapshoot, however, Maxwell said, and it might still be weeks or even months before they get the winning pull of the slot machine handle.

Maxwell is optimistic, and although he didn’t give any percentages on how likely it is that Spirit will wake up, he said the situation is certainly not dire…yet.

“Having said all that, it would be awfully nice to actually get a beep from Spirit and know she’s there,” Maxwell said. “I miss her. I hope she calls home soon.”

Sniff.

Hang in there, Spirit. And you, too, Scott, and all your rover compatriots.

Posted on by Nancy Atkinson

Astronomer Brian Marsden Has Died

Dr. Brian Marsden Credit: Harold Dorwin

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From a Harvard Smithsonian Center for Astrophysics press release:

Dr. Brian Marsden passed away today at the age of 73 following a prolonged illness. He was a Supervisory Astronomer at the Smithsonian Astrophysical Observatory and Director Emeritus of the Minor Planet Center.

“Brian was one of the most influential comet investigators of the twentieth century,” said Charles Alcock, Director of the Harvard-Smithsonian Center for Astrophysics, “and definitely one of the most colorful!”

Dr. Marsden specialized in celestial mechanics and astrometry, collecting data on the positions of asteroids and comets and computing their orbits, often from minimal observational information. Such calculations are critical for tracking potentially Earth-threatening objects. The New York Times once
described Marsden as a “Cheery Herald of Fear.”

The comet prediction of which Marsden was most proud was that of the return of Comet Swift-Tuttle, which is the comet associated with the Perseid meteor shower each August. Swift-Tuttle had been discovered in 1862, and the conventional wisdom was that it would return around 1981. Marsden had a strong suspicion, however, that the 1862 comet was identical with one seen in 1737, and this assumption allowed him to predict that Swift-Tuttle would not return until late 1992. This prediction proved to be correct. This comet has the longest orbital period of all the comets whose returns have been successfully predicted.

In 1998, Marsden developed a certain amount of notoriety by suggesting that an object called 1997 XF11 could collide with Earth. He said that he did this as a last-ditch effort to encourage the acquisition of further observations, including searches for possible data from several years earlier. The recognition of some observations from 1990 made it quite clear that there could be no collision with 1997 XF11 during the foreseeable future.

Dr. Marsden also played a key role in the “demotion” of Pluto to dwarf planet status. He once proposed that Pluto should be cross-listed as both a planet and a “minor planet,” and assigned the asteroid number 10000. That proposal was not accepted. However, in 2006 a vote by members of the International Astronomical Union created a new category of “dwarf planets,” which includes Pluto, Ceres, and several other objects. Pluto was designated minor planet 134340. This decision remains controversial.

Note: You can read Mike Brown’s post on his blog about Marsden, including an excerpt from Brown’s new book that exemplifies Marsden’s colorful, but equally pleasant demeanor.

Marsden was born on August 5, 1937, in Cambridge, England. He received an undergraduate degree in mathematics from New College, University of Oxford, and a Ph.D. from Yale University.

At the invitation of director Fred Whipple, Dr. Marsden joined the staff of the Smithsonian Astrophysical Observatory in Cambridge, Mass., in 1965. He became director of the Minor Planet Center in 1978. (The MPC is the official organization in charge of collecting observational data for asteroids and comets, calculating their orbits, and publishing this information via Circulars.) Marsden served as an associate director of the Harvard-Smithsonian Center for Astrophysics from 1987 to 2003 (the longest tenure of any of the Center’s associate directors).

Among the various awards he received from the U.S., the U.K., and a handful of other European countries, the ones he particularly appreciated were the 1995 Dirk Brouwer Award (named for his mentor at Yale) from the American Astronomical Society’s (AAS) Division on Dynamical Astronomy, and the 1989 Van Biesbroeck Award (named for an old friend and observer of comets and double stars), then presented by the University of Arizona (now by the AAS) for service to astronomy.

Dr. Marsden married Nancy Lou Zissell, of Trumbull, Connecticut, on December 26, 1964, and fathered Cynthia Louise Marsden-Williams (who is now married to Gareth Williams, still MPC associate director), of Arlington, Massachusetts, and Jonathan Brian Marsden, of San Mateo, California. He also has three grandchildren in California: Nikhilas, Nathaniel, and Neena. A sister, Sylvia Custerson, continues to reside in Cambridge, England.

Posted on by Tammy Plotner

Red Sky In The Morning…

“Red sky in the morning… Sailors take warning!” How many of you have heard of that old phrase? Just look at this beautiful panorama of Cairns, Australia done by Joe Brimacombe – does it portend foul weather ahead or are such sayings a myth? Step inside and let’s find out…

In present time we recognize such beautiful clouds to be a reflection from the rising Sun, but in times past mankind relied on such fanciful wordsmithing to help them predict weather patterns crucial to farmers and sailors. Can the appearance of the sky and appearance of the clouds really foretell the atmospheric future? You just might be surprised…

Generally our weather moves in the opposite direction – west to east – from which our Earth turns. It’s carried along by the romantic westerly trade winds, meaning storm systems are more likely to arrive from the west. We know the brilliant and varied colors we see in the sky are caused by sunlight being refracted into almost all the colors of the spectrum as they pass through our atmosphere and bounce off the water vapor and fine particles present in Earth’s atmosphere. The amount, of which, are darn good indications of weather-to-be!

At both rise and set, the Sun is low on the horizon and the light coming through is penentrating the very thickest part of Earth’s atmosphere. When skies appear red, we know it carries a concentration of both moisture and dust particles. We perceive red because the longest wavelengths in the visible spectrum dictate it. The shorter blue wavelengths are dispersed. Therefore a red sunrise means the Sun is reflecting from dust particles and clouds that have passed from the west and a storm may be following in from the east. Watch for the skies themselves to change color, too… Because if they should appear a deep, brilliant red? That means there’s a high moisture content in the atmosphere and rain is usually on the way!

And now you know…

Many thanks to Dr. Joseph Brimacombe for sharing his awesome photo taken from Coral Towers Observatory, Cairns, Australia. You rock, Doc!

Posted on by Nancy Atkinson

Exoplanet of Extragalactic Origin Could Foretell Our Solar System’s Future

Artist's impression of a yellowish star being orbited by an extra-solar planet. Credit: ESO/L. Calçada

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While astronomers have detected over 500 extrasolar planets during the past 15 years, this latest one might have the most storied and unusual past. But its future is also of great interest, as it could mirror the way our own solar system might meet its demise. This Jupiter-like planet, called HIP 13044 b, is orbiting a star that used to be in another galaxy but that galaxy was swallowed by the Milky Way. While astronomers have never directly detected an exoplanet in another galaxy, this offers evidence that other galaxies host stars with planets, too. The star is nearing the end of its life and as it expands, could engulf the planet, just as our Sun will likely snuff out our own world. And somehow, this exoplanet has survived the first death throes of the star.

“The star is in the horizontal branch stage and it still has a planet, which is a glimmer of hope for those of us who worry about how our Solar System will look in 5 billion years,” said Markus Poessel, from the Max-Planck-Institut für Astronomie (MPIA) press office.


The star, HIP 13044, lies about 2,000 light-years from Earth in the southern constellation of Fornax (the Furnace). It is part of the so-called Helmi stream, a group of stars that originally belonged to a dwarf galaxy that was devoured by the Milky Way, probably about six to nine billion years ago.

The planet was detected using the radial velocity method — astronomers saw tiny telltale wobbles of the star caused by the gravitational tug of an orbiting companion. The instrument used was FEROS, a high-resolution spectrograph attached to the 2.2-meter MPG/ESO telescope at the La Silla Observatory in Chile.

“This discovery is very exciting,” says Rainer Klement from MPIA, who selected the target stars for this study. “For the first time, astronomers have detected a planetary system in a stellar stream of extragalactic origin. Because of the great distances involved, there are no confirmed detections of planets in other galaxies. But this cosmic merger has brought an extragalactic planet within our reach.”

Last year, another group of astronomers claimed the detection of an extragalactic exoplanet through “pixel lensing” where the planet passing in front of an even more distant star leads to a subtle, but detectable flash. However, this method relies on a singular event — the chance alignment of a distant light source, planetary system and observers on Earth — and there has been no confirmation of this exoplanet.

This artist’s impression shows HIP 13044 b, an exoplanet orbiting a star that entered our galaxy, the Milky Way, from another galaxy. Credit: ESO/L. Calçada

HIP 13044 is in the red giant phase of stellar evolution, and this exoplanet must have survived the period when its host star expanded massively after exhausting the hydrogen fuel supply in its core . The star has now contracted again and is burning helium in its core. Until now, these horizontal branch stars have remained largely uncharted territory for planet-hunters.

“This discovery is part of a study where we are systematically searching for exoplanets that orbit stars nearing the end of their lives,” says Johny Setiawan, also from MPIA, who led the research. “This discovery is particularly intriguing when we consider the distant future of our own planetary system, as the Sun is also expected to become a red giant in about five billion years.”

Our sun is going down the same stellar evolutionary path as HIP 13044, so astronomers may be able to determine the fate of our solar system by studying the system.

Setiawan told Universe Today that he and his team will continue to observe HIP 13044 and other stars in the group to search for other planets. “It is of course difficult to follow how this particular star evolves over time,” he said, “but if you just observe other stars with different evolutionary phase, you can also complete the picture without waiting until this one single star evolves.”

How has this planet survived so far?

“The star is rotating relatively quickly for a horizontal branch star,” said Setiawan. “One explanation is that HIP 13044 swallowed its inner planets during the red giant phase, which would make the star spin more quickly.”

HIP 13044b probably once orbited much farther away from the star but spiraled inwards as the star began to spin faster.

The star also poses interesting questions about how giant planets form, as the star appears to contain very few elements heavier than hydrogen and helium — fewer than any other star known to host planets, and Setiawan said it is a puzzle how such a star could have formed a planet.

“There is indeed a possibility to form planets around metal-poor stars due to gravitational disk instability, which is an alternative to the core accretion model,” Setiawan said in an email. “But, for such a very metal poor star like HIP 13044, I am also not completely sure if the disk instability model can also explain the whole process. Still, it is probably the best explanation for this particular system.”

Source: Max Planck institute for Astronomy, ESO, email exchange with Setiawan

Posted on by Nancy Atkinson

Anti-hydrogen Captured, Held For First Time

The electrodes (gold) of the trap used to combine positrons and antiprotons to form antihydrogen.N. MADSEN, ALPHA/SWANSEA

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Can warp drive be far behind? A paper published in this week’s edition of Nature reports that for the first time, antimatter atoms have been captured and held long enough to be studied by scientific instruments. Not only is this a science fiction dream come true, but in a very real way this could help us figure out what happened to all the antimatter that has vanished since the Big Bang, one of the biggest mysteries of the Universe. “We’re very excited about the fact that we can actually now trap antimatter atoms long enough to study their properties and see if they’re very different from matter,” said Makoto Fujiwara, a team member from ALPHA, an international collaboration at CERN.

Antimatter is produced in equal quantities with matter when energy is converted into mass. This happens in particle colliders like CERN and is believed to have happened during the Big Bang at the beginning of the universe.

“A good way to think of antimatter is a mirror image of normal matter,” said team spokesman Jeffrey Hangst, a physicist at Aarhus University in Denmark. “For some reason the universe is made of matter, we don’t know why that is, because you could in principle make a universe of antimatter.”

In order to study antimatter, scientists have to make it in a laboratory. The ALPHA collaboration at CERN has been able to make antihydrogen – the simplest antimatter atom – since 2002, producing it by mixing anti- protons and positrons to make a neutral anti-atom. “What is new is that we have managed to hold onto those atoms,” said Hangst, by keeping atoms of antihydrogen away from the walls of their container to prevent them from getting annihilated for nearly a tenth of a second.

The antihydrogen was held in an ion trap, with electromagnetic fields to trap them in a vacuum, and cooled to 9 Kelvin (-443.47 degrees Fahrenheit, -264.15 degrees Celsius). To actually see if they made any antihydrogen, they release a small amount and see if there is any annihilation between matter and antimatter.

The next step for the ALPHA collaboration is to conduct experiments on the trapped antimatter atoms, and the team is working on a way to find out what color light the antihydrogen shines when it is hit with microwaves, and seeing how that compares to the colors of hydrogen atoms.

CERN Press release

ALPHA collaboration

Nature article.

Posted on by Nancy Atkinson

Hollywood-like Galactic Encounter Results in Baby Stars

Images of the core of NGC 4150, taken in near-ultraviolet light with the sharp-eyed Wide Field Camera 3 (WFC3). Credit: NASA, ESA, R.M. Crockett (University of Oxford, U.K.), S. Kaviraj (Imperial College London and University of Oxford, U.K.), J. Silk (University of Oxford), M. Mutchler (Space Telescope Science Institute, Baltimore), R. O'Connell (University of Virginia, Charlottesville), and the WFC3 Scientific Oversight Committee

Like news ripped from a Hollywood tabloid, this saga includes an encounter between two individuals; one aging, and thought to be past its prime, the other youthful and vigorous. And for good measure, thrown in on this story are cannibalism and even zombies. The result of the meet-up? Babies. Baby stars, that is, and the individual galaxies in this tale ended up, seemingly, living together happily-ever-after. The Hubble Space Telescope’s Wide Field Camera 3 (WFC3) captured images of NGC 4150, an aging elliptical galaxy, and at the core of the galaxy was some vigorous star birth. The star-making days of this galaxy should have ended long ago, but here was active star birth taking place. This isn’t the first time astronomers have seen something like this, so they took a closer look.
Continue reading “Hollywood-like Galactic Encounter Results in Baby Stars”

Posted on by Matt Williams

Tertiary Period

Tertiary Period
Geologic Time Scale. Image Credit: USGS

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When it comes to the geological timeline, there are several periods that scientists and biologists recognize as being of extreme importance to the development of life on Earth. There’s the Hadean period, which began with the creation of the Earth and was marked by the formations of the oceans and atmosphere. Or the Cambrian period, when the massive continent of Pangaea broke up and allowed for the explosion of life which led to the development of all modern Phyla. But when it comes to us mammals, perhaps the most important period was the one known as the Tertiary Period. This period began 65 million years ago and ended roughly 1.8 million years ago and bore witness to some major geological, biological and climatological events. This included the current configuration of the continents, the cooling of global temperatures, and the rise of mammals as the planet’s dominant vertebrates. It followed the Cretaceous period and was superseded by the Quaternary.

In terms of major events, the Tertiary period began with the demise of the non-avian dinosaurs in the Cretaceous–Tertiary extinction event, at the start of the Cenozoic era, and lasted to the beginning of the most recent Ice Age at the end of the Pliocene epoch. In terms of geology, there was a great deal of tectonic activity that continued from the previous era, culminating in the splitting of Gondwana and the collision of the Indian landmass with the Eurasian plate. This led to the formation of the Himalayas, the gradual creation of the continent of Australia (a haven for the non-placental, marsupial mammals), the separation South America from West Africa and its connection to North America, and Antarctica taking its current position below the South Pole. In terms of climate, the period was marked by widespread cooling, beginning in the Paleocene with tropical-to-moderate worldwide temperatures and ending before the first extensive glaciation at the start of the Quaternary.

In terms of species evolution, this period was of extreme importance to modern life. By the beginning of the period, mammals replaced reptiles as the dominant vertebrates on the planet. In addition, all non-avian dinosaurs (referring to terrestrial dinosaurs and not their avian descendants) had all become extinct by the beginning of this period. Modern types of birds, reptiles, amphibians, fish, and invertebrates were already numerous at the beginning of this period but also continued to appeared early on, and many modern families of flowering plants evolved. And last, but certainly not least (at least for us human folk), the earliest recognizable hominid relatives of humans appeared. One striking example of this is the Proconsul Primate, a tree-dwelling Primate that existed from roughly 23 to 17 million years ago and who’s fossilized remains have been found today in modern Kenya, Uganda and other East African locales.

We have written many articles about Tertiary Period for Universe Today. Here’s an article about the Quaternary Period, and here’s an article about the asteroid extinction theory.

If you’d like more info on the Tertiary Period, check out the USGS Geologic Time Scale, and here’s a link to another article about the Tertiary Period.

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

Sources:
http://en.wikipedia.org/wiki/Tertiary
http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Tertiary_extinction_event
http://en.wikipedia.org/wiki/Gondwana#Cenozoic
http://en.wikipedia.org/wiki/Proconsul_%28genus%29
http://en.wikipedia.org/wiki/Dinosaur

Posted on by Matt Williams

Super Magnets

Permanent Magnet
Super Magnets, the strongest type of permanent magnets

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Magnets are not only a source of endless fun – for children and children of all ages! They also happen to have endless industrial applications. But when it comes to the high-tech industry, the people who rely on magnetic materials to build appliances, electronics, or even spaceships, only one type of magnet will do. These are known as Rare Earth or Super Magnets, the kind that are used in MRI machines, computer hard drives, electric and hybrid motors, audio speakers, electric guitars, and race car engines. In spite of their name, the elements used to make super magnets are actually quite common, but were rarely found in large enough quantities to be considered economically viable. However, since the 90’s these magnets have become cheap and widely available, and are even being considered for additional processes.

The term super magnet is a broad term and encompasses several families of rare-earth magnets that include seventeen elements in the periodic table; namely scandium, yttrium, and the fifteen lanthanides. First developed in the 1970’s and 80’s, super magnets are the strongest type of permanent magnets ever made, are ferromagnetic, meaning that like iron they can be magnetized, and have Curie temperatures that are below room temperature. This means that in their pure form, their magnetism only appears at low temperatures. However, since they can form compounds with transition metals such as iron, nickel, and cobalt, metals that have Curie temperatures well above room temperature, they can be used effectively at higher temperatures as well. The main advantage they have over conventional magnets is that their greater strength allows for smaller, lighter magnets to be used, ones that can do the same job but take up less space and require less material.

Super magnets can be broken down into two categories. First, there is the neodymium magnet, which is made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. This material is currently the strongest known type of permanent magnet and was developed in the 1980’s. It is typically used in the construction of head actuators in computer hard drives and has many electronic applications, such as electric motors, appliances, and magnetic resonance imaging (MRI). The second type of super magnet is the samarium-cobalt variety, an alloy of samarium and cobalt with the chemical formula of SmCo5. This second-strongest type of rare Earth magnet is also used in electronic motors, turbomachinery, and because of its high temperature range tolerance may also have many applications for space travel, such as cryogenics and heat resistant machinery.

We have written many articles about magnets for Universe Today. Here’s an article about where to buy magnets, and here’s an article about what magnets are made of.

If you’d like more info on Super Magnets, check out Rare Earth Magnetics Homepage, and here’s a link to Wikipedia: Rare Earth Magnets.

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

Sources:
http://en.wikipedia.org/wiki/Rare-earth_magnet
http://en.wikipedia.org/wiki/Magnet
http://en.wikipedia.org/wiki/Samarium-cobalt_magnet
http://en.wikipedia.org/wiki/Neodymium_magnet
http://www.newton.dep.anl.gov/askasci/phy99/phy99010.htm