The Ark Of Millions Of Years Volume Four

NASA-funded researchers are monitoring a rarefied layer of gas around the Earth called "the thermosphere," because it recently collapsed and now is rebounding again. "This is the biggest contraction of the thermosphere in at least 43 years," says John Emmert of the Naval Research Lab, lead author of a paper announcing the finding in the June 19th issue of the Geophysical Research Letters (GRL). "It's a Space Age record." The collapse happened during the deep solar minimum of 2008-2009. The thermosphere always cools and contracts when solar activity is low; however, the magnitude of the collapse was two to three times greater than low solar activity could explain. "Something is going on that we do not understand," says Emmert. The thermosphere ranges in altitude from 90 km to 600+ km and is also where solar radiation, and as it turns out galactic radiation, makes first contact with our planet. The thermosphere intercepts extreme ultraviolet (EUV) photons from the sun before they can reach the ground. When solar activity is high, solar EUV warms the thermosphere, causing it to puff up like a marshmallow held over a camp fire. (This heating can raise temperatures as high as 1400 K—hence the name thermosphere.) When solar activity is low, the opposite happens. 67 Lately, solar activity has been very low. In 2008 and 2009, the sun plunged into a millennium-class solar minimum. Sunspots still are scarce, solar flares almost non-existent, and solar EUV radiation at a low ebb. Researchers immediately turned their attention to the thermosphere to see what would happen. How do you know what's happening all the way up in the thermosphere? Emmert uses a clever technique: Because satellites feel aerodynamic drag when they move through the thermosphere, it is possible to monitor conditions there by watching satellites decay. He analyzed the decay rates of more than 5000 satellites ranging in altitude between 200 and 600 km and ranging in time between 1967 and 2010. This provided a unique space-time sampling of thermospheric density, temperature, and pressure covering almost the entire Space Age. In this way he discovered that the thermospheric collapse of 2008-2009 was not only bigger than any previous collapse, but also bigger than the sun alone could explain. One possible explanation is carbon dioxide (CO2). When carbon dioxide gets into the thermosphere, it acts as a coolant, shedding heat via infrared radiation. It is widely-known that CO2 levels have been increasing in Earth's atmosphere. Extra CO2 in the thermosphere could have magnified the cooling action of solar minimum. "But the numbers don't quite add up," says Emmert. "Even when we take CO2 into account using our best understanding of how it operates as a coolant, we cannot fully explain the thermosphere's collapse." About 60% of the thermosphere collapse is not accounted for, considering the loss due to CO2 cooling, and other usual causes. Authors of the GRL paper acknowledge that the situation is complicated. There's more to it than just solar EUV and terrestrial CO2. The overall sensitivity of the thermosphere to solar radiation could actually be increasing. There could be effects that we only see in this neighborhood of the galaxy, one that is visited every 26,000 years as the solar system travels through the Precession. "The density anomalies," they wrote, "may signify that an as-yet-unidentified climatological tipping point involving energy balance and chemistry feedbacks has been reached." Scientists who were not fortunate enough to read the first three volumes of The Ark of Millions of Years, are left surprised and grasping for theories after the Voyager Spacecrafts emerged from the heliosphere far ahead of their schedules. What was even more amazing is waiting for the exploration vehicles on the outside was not the quiet, cool microwave hum left over from the theoretical Big Bang. They found instead something that should not have been there at all. The solar system is passing through an interstellar cloud that physics says should not exist. In the Dec. 24th issue of Nature, a team of scientists reveal how NASA's Voyager spacecraft have solved the mystery. "Using data from Voyager, we have discovered a strong magnetic field just outside the solar system," explains lead author Merav Opher, a NASA Heliophysics Guest Investigator from George Mason University. "This magnetic field holds the interstellar cloud together and solves the long-standing puzzle of how it can exist at all." 69 Voyager flew through the outer bounds of the heliosphere en route to interstellar space. A strong magnetic field reported by Opher et al in the Dec. 24, 2009, issue of Nature is delineated in yellow. Image copyright 2009, The American Museum of Natural History. The discovery has implications for the future when the solar system will eventually bump into other, similar clouds in our arm of the Milky Way galaxy. Exactly as predicted by the authors in the chapter called The Cataclysms Arrive, Astronomers discovered what they are calling the Local Interstellar Cloud or "Local Fluff" for short. It's about 30 light years wide and contains a wispy mixture of hydrogen and helium atoms at a temperature of 6000 C. The existential mystery of the Fluff has to do with its surroundings. About 10 million years ago, a cluster of supernovas exploded nearby, creating a giant bubble of million-degree gas. The Fluff is completely surrounded by this high-pressure supernova exhaust and should be crushed or dispersed by it. "The observed temperature and density of the local cloud do not provide enough pressure to resist the 'crushing action' of the hot gas around it," says Opher. So how does the Fluff survive? The Voyagers have found an answer. "Voyager data show that the Fluff is much more strongly magnetized than anyone had previously suspected—between 4 and 5 microgauss*," says Opher. "This magnetic field can provide the extra pressure required to resist destruction." This clearly supports the prediction made by the authors that the Solar system would pass through a plane of highly magnetized gaseous matter before the year 2012, and that it was the result of alignment with the rift in the Milky Way Galaxy. NASA's two Voyager probes have been racing out of the solar system for more than 30 years. They are now beyond the orbit of Pluto and on the verge of entering interstellar space—but they are not there yet. "The Voyagers are not actually inside the Local Fluff," says Opher. "But they are getting close and can sense what the cloud is like as they approach it." The space explorers will reach the edge of the cloud sometime in the year 2011, with the Solar system not far behind, The Fluff is held at bay just beyond the edge of the solar system by the sun's magnetic field, which is inflated by solar wind into a magnetic bubble more than 10 billion km wide. Called the "heliosphere," this bubble acts as a shield that helps protect the inner solar system from galactic cosmic rays and interstellar clouds. The two Voyagers are located in the outermost layer of the heliosphere, or "heliosheath," where the solar wind is slowed by the pressure of interstellar gas. But in recent years, the Solar wind has dropped to around 300 km/sec, making a weak challenger against this new more powerful galactic wind. Voyager 1 entered the heliosheath in Dec. 2004; Voyager 2 followed almost 3 years later in Aug. 2007. These crossings were key to Opher et al's discovery. The fact that the Fluff is strongly magnetized means that other clouds in the galactic neighborhood could be, too. Eventually, the solar system will run into some of them, and their strong magnetic fields could compress the heliosphere even more than it is compressed now.