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Posts Tagged ‘Antarctica’

Search for Traces of Ancient Supernova in Antarctica

Posted by jase on July 18, 2009

Japanese scientists journeyed to Antarctica to recover evidence of alterations to Earth’s atmosphere caused in medieval times by supernovae recorded by scholars – including obscure Irish monasteries where monks later interpreted them signs of the Antichrist . No, this isn’t the plot of the next Dan Brown novel (or a Dan Brow fanfiction written by an X-Files addict): this is real science.

Supernovae release terrific amounts of energy, as in “If one happened too close, the planet would be sterilized” truly terror-inducing terrific.  Some of this energy is fired off as gamma rays, which can travel thousands of light-years and still pack enough of a punch after to alter the atmosphere – which is exactly what happened in 1006 and again in 1054, when gamma rays blasted the upper atmosphere and created spikes in NO3 levels.  There was also quite a lot of visible light, creating a star visible even during the day which was noted by various Chinese, Egyptian and even monastic records.

To access past records of the atmosphere, a team of Japanese scientists carefully extracted 122 meters of ice core from Antarctica.  Even better, to locate events on such a stretch of frozen time you use known volcanic atmosphere-altering events as reference points – in other words, these guys use exploding mountains as a ruler. 

The team found NO3 spikes at times corresponding to 1006 and 1054, as well as a mysterious unknown third event – and we remind you that this is not a movie, even though that sounds so much like a second act reveal leading to a lost city or something, we can practically see Nicolas Cage’s shocked expression.

Unlike any movie adventurer of the unknown, who has a tendency to steal/detonate every single relic they find, the Japanese team have also made things easier for anyone who follows them.  The unprecedented detail of their observations reveals a standard 11-year cycle in ice-core records, corresponding to the sunspot cycle. This will help future ice-core observers track the time of events.

These people look at timescales so huge that the pulsing of the sun itself is just the ticking of a clock.

Posted in Antarctica, Climate, Earth, Global Warming, Historic Events, Science, Southern Hemisphere | Tagged: , , , , , , , | Leave a Comment »

Ever Heard of: Auroras

Posted by jase on July 7, 2009

Auroras, sometimes called the northern and southern (polar) lights or aurorae (singular: aurora), are natural light displays in the sky, usually observed at night, particularly in the polar regions. They typically occur in the ionosphere. They are also referred to as polar auroras. In northern latitudes, the effect is known as the aurora borealis, named after the Roman goddess of dawn, Aurora, and the Greek name for north wind, Boreas by Pierre Gassendi in 1621. The aurora borealis is also called the northern polar lights, as it is only visible in the sky from the Northern Hemisphere, the chance of visibility increasing with proximity to the North Magnetic Pole, which is currently in the arctic islands of northern Canada. Auroras seen near the magnetic pole may be high overhead, but from further away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the sun was rising from an unusual direction. The aurora borealis most often occurs from September to October and from March to April. The northern lights have had a number of names throughout history. The Cree people call this phenomenon the “Dance of the Spirits.” Auroras can be spotted throughout the world. It is most visible closer to the poles due to the longer periods of darkness and the magnetic field.

Its southern counterpart, the aurora australis or the southern polar lights, has similar properties, but is only visible from high southern latitudes in Antarctica, South America, or Australasia. Australis is the Latin word for “of the South.”

Benjamin Franklin first brought attention to the “mystery of the Northern Lights.” He theorized the shifting lights to a concentration of electrical charges in the polar regions intensified by the snow and other moisture.

The phenomenon of aurora is an interaction between the Earth’s magnetic field and solar wind.

Auroras are produced by the collision of charged particles from Earth’s magnetosphere, mostly electrons but also protons and heavier particles, with atoms and molecules of Earth’s upper atmosphere (at altitudes above 80 km (50 miles)). The particles have energies of 1 to 100 keV. They originate from the Sun and arrive at the vicinity of Earth in the relatively low-energy solar wind. When the trapped magnetic field of the solar wind is favorably oriented (principally southwards) it connects with Earth’s magnetic field, and solar particles enter the magnetosphere and are swept to the magnetotail. Further magnetic reconnection accelerates the particles towards Earth.

The collisions in the atmosphere electrically excite electrons to take quantum leaps (a mechanism in which the electron’s kinetic energy is converted to visible light); and molecules in the upper atmosphere. The excitation energy can be lost by light emission or collisions. Most auroras are green and red emissions from atomic oxygen. Molecular nitrogen and nitrogen ions produce some low level red (pink) and very high blue/violet auroras. The light blue and green colors are produced by ionic nitrogen and the neutral helium gives off the purple colour whereas neon is responsible for the rare orange flares with the rippled edges. Different gasses interacting with the upper atmosphere will produce different colors, caused by the different compounds of oxygen and nitrogen. The level of solar wind activity from the Sun can also influence the color and intensity of the auroras.

The Earth is constantly immersed in the solar wind, a rarefied flow of hot plasma (gas of free electrons and positive ions) emitted by the Sun in all directions, a result of the million-degree heat of the Sun’s outermost layer, the corona.

The IMF originates on the Sun, related to the field of sunspots, and its field lines (lines of force) are dragged out by the solar wind. That alone would tend to line them up in the Sun-Earth direction, but the rotation of the Sun skews them (at Earth) by about 45 degrees, so that field lines passing Earth may actually start near the western edge (“limb”) of the visible sun.[9]

Earth’s magnetosphere is the space region dominated by its magnetic field. It forms an obstacle in the path of the solar wind, causing it to be diverted around it, at a distance of about 70,000 km (before it reaches that boundary, typically 12,000–15,000 km upstream, a bow shock forms). The width of the magnetospheric obstacle, abreast of Earth, is typically 190,000 km, and on the night side a long “magnetotail” of stretched field lines extends to great distances.

When the solar wind is perturbed, it easily transfers energy and material into the magnetosphere. The electrons and ions in the magnetosphere that are thus energized move along the magnetic field lines to the polar regions of the atmosphere.

The aurora is a common occurrence in the Poles. It is occasionally seen in temperate latitudes, when a strong magnetic storm temporarily expands the auroral oval. Large magnetic storms are most common during the peak of the eleven-year sunspot cycle or during the three years after that peak. Geomagnetic storms that ignite auroras actually happen more often during the months around the equinoxes. It is not well understood why geomagnetic storms are tied to Earth’s seasons while polar activity is not.

Posted in Astronomy, Earth, Science, Solar Energy, Space | Tagged: , , , , , , , , , | Leave a Comment »

Earth Will Become Planet Without Ice Caps

Posted by jase on June 28, 2009

Rising sea levels will not extinguish humanity, but they will transform life on planet Earth as we know it according to Peter Ward professor of biology and earth sciences at the University of Washington. Here are his predictions in a new book, The Flooded Earth, which will be published this July.

By 2050: Sea levels will rise 0.5 to 1 meter. Well established coastal cities will battle the rising waters with dikes and levees; other cities will see their underground infrastructure impaired and face building collapse.

By 2300: The seas will rise 20 meters reshaping the world’s geography, forming new rivers and lakes as Antarctica’s ice melts. Massive icebergs will form in the southern hemisphere interrupting historic shipping lanes.

2500-3000: the sea will reach its maximum levels completely wiping out coastal cities and forcing massive human and animal migration. Greenland and Antarctica will be transformed into prime farmlands. Southern regions will face the spread of tropical diseases and the possibility of mass extinctions.

Image above: Red represents areas where temperatures have increased the most during the last 50 years, particularly in West Antarctica, while dark blue represents areas with a lesser degree of warming. Temperature changes are measured in degrees Celsius. Credit: NASA/GSFC Scientific Visualization Studio.

Further reading:

Is Global Warming Part of Earth’s Natural Cycle: MIT Team Says “Yes” -A Galaxy Insight

Global-Warming Tipping Point: 9 Degrees Temperature Increase Would Devastate Earth’s Population

Source: http://www.nasa.gov/topics/earth/features/warming_antarctica.html

Posted in Antarctica, Earth, Global Warming, Historic Events, Southern Hemisphere | Tagged: , , , , | Leave a Comment »

Ever Heard Of: The Antarctic Circumpolar Current

Posted by jase on June 24, 2009

The Antarctic Circumpolar Current (ACC) is an ocean current that flows from west to east around Antarctica. An alternate name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and, at approximately 125 Sverdrups, the largest ocean current. It keeps warm ocean waters away from Antarctica, enabling that continent to maintain its huge ice sheet.

The ACC has been known to sailors for many years; circumstances preceding the Mutiny on the Bounty and Jack London’s story “Make Westing” poignantly illustrated the difficulty it caused for mariners seeking to round Cape Horn on the clipper ship route between New York and California.

The current creates two Antarctic gyres, and is the strongest current system in the world oceans, the one that links the Atlantic, Indian and Pacific basins.

An expedition in May 2008 by 19 scientists studied the geology and biology of eight Macquarie Ridge sea mounts, as well as the Antarctic Circumpolar Current to investigate the effects of climate change of the southern Ocean. The circumpolar current merges the waters of the Atlantic, Indian, and Pacific Oceans and carries up to 150 times the volume of water flowing in all of the world’s rivers. After studying the circumpolar current it is clear that it strongly influences regional and global climate as well as underwater biodiversity.

Further Reading:

Cape Horn

Antarctica

Drake Passage

Posted in Antarctica, Earth, South America, Southern Hemisphere | Tagged: , , , , , , , | Leave a Comment »