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----------------------------- 1924 - Visitors from outer space.
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- There is a giant hole in the Earth. It is at the tip of the Yucatan Peninsula, Mexico, at the town of Chicxulub. The town is where a 6-mile wide asteroid hit the Earth. The impact crater is 110 miles wide.
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- Standing at the rim of the crater 2,000 feet above the surface you are 12 miles above the bottom of the crater. But, over the past 66 million years the crater has been filled in. There are nearly 1,000 sinkholes forming a radius of 55 miles tracing the boundary of the crater’s outer rim. Today these sinkholes are a valuable source of fresh water for the region.
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- This global event that occurred 66,000,000 years ago is credited with annihilating 75% of living species on Earth.
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- The impact was so strong it created tsunamis, earthquakes, volcanic eruptions, and an ash cloud that circled the planet.
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- “asteroid day.org” is a website recognizing the June 30, 1908, asteroid that exploded over Tunguska, Russia. The atmospheric explosion flattened 800 square miles of tundra forest.
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- Outer space does not just touch us with asteroids. There is a dust from comets that slam into our upper atmosphere every day. Cosmic Rays are higher speed atoms (particles misnamed as rays) that collide with atoms in our atmosphere. The Solar Wind enters our magnetic poles creating the aurora Northern Lights.
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- Another visitor is the remnants of a supernova The explosion‘s particles reaching us include “ iron - 60”. The iron elements on Earth are iron-56, 26 protons and 30 neutrons. The iron-60 from supernova explosions have 4 additional neutrons and is an unstable radioactive isotope.
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- The Crab Nebula is an expanding explosion from Supernova 1054. This explosion also throws iron-60 into space. Iron-60 is found in magnet fossils, bacteria in sediments found on the floor of the Pacific Ocean. The bacteria dissolve but the magnetic crystals are preserved in the sediment. So are the iron-60 atoms.
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- The half-life for radioactive decay of iron-60 is 2.6 million years. Therefore, this is not iron-60 from primordial Earth. More likely it is from a more recent supernova explosion.
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- Our early human ancestors were making stone tools 2.2 million yeas ago. Bacteria munching on supernova ash are giving us new insights of what was going on back then.
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- In February, 1987, a bright new star erupted in the Large Magellanic Cloud. The “ Cloud” is a satellite galaxy that is 165,000 lightyears away from the Milky Way Galaxy. It is the most distant naked-eye star explosion in recorded history. It reached a peak luminosity Magnitude of +2.9. ( The brightest star in the night sky is -1.5 Magnitude )
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- This Supernova SN1987 is the brightest observed since Kepler’s Supernova in 1604 which occurred in our Milky Way Galaxy. Today, 30 years later, the SN1987 is 10 million times fainter. The star that exploded in the LMC was a 12th Magnitude blue super giant star of spectral type B3Ia. It is believed to have began as an 18 Solar Mass star. The explosion created radioactive elements that powered the emissions over years following. Nickel-56 decayed into Colbalt-56. Titanium-44 decayed with a half life of 1,200 days.
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- Since 2001 a re-brightening of SN1987 has occurred that is not powered by radioactive decay. The new power source is the violent collisions of the blast wave with the outer ring converting kinetic energy into heat. The heated material shines in X-rays.
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- The collisions are also accelerating electrons to relativistic energies. Interacting with magnetic fields produce radio waves. This is called Synchrotron Radiation.
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- The last supernovae “recorded” in the Milky Way were Kepler’s 1604 and Tycho’s 1572. We are due another one. On average a supernova occurs in our Galaxy every 100 years.
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- Supernovae from massive stars create Neutron Stars. More massive supernovae create Blackholes. The Neutron Star is compressed to a 12 kilometers diameter. The core heats up to 100 billion Kelvin. 10% of the core’s mass flies out as Neutrinos carrying off a vast amount of energy in less than 13 seconds.
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- Today SN1987 has two larger, fainter rings in a tilted hour-glass shape. The blasts ultraviolet pulse traveling at 10% the speed of light due to collisions with gas and dust. Some 30 of these “ hot spots” appeared as a ring of pearls. The necklace of pearls was produced in the denser fingers of the expanding gas. The fingers are merging and fading now.
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- The iron in your blood came form a star core explosion like this. Much of the star’s debris is kept hot and glowing by the decay of radioactive nuclei. Nickle-56 decays to Cobalt-56 in 6 days. Then that decays into Iron-56 in another 111 days.
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- Complete radioactive brightening fades away after 5,000 days. The re-brightening is created by violent collisions of the blast wave turning energy into heat and X-rays.
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- Electrons interacting with the magnetic field emits radio waves ( synchrotron radiation).
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- This supernovae destruction and creation has occurred over the last 30 years. Kepler 1604 and Tycho 1572 in our Milky Way are evidence of older supernovae explosions.
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- A reminder, on average a galaxy the size of the Milky Way experiences a supernova every 100 years. We are due. An announcement will be made shortly, stay tuned.
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- See #1923 Asteroid Bennu. A mission to visit an asteroid in 2017.
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----- 707-536-3272 ---------------- Friday, January 27, 2017 -----
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