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When the universe turns
bad April 8, 2009 Commentary: Earth in danger! When the universe turns bad by Neil deGrasse Tyson http://tinyurl.com/whenuniverseturnsbad - - - Complete article: In the face of disaster, optimists tend to be grateful because they easily imagine how much worse things could have been. Count astrophysicists among them. When we hear about earthly problems, many of us think to ourselves, "You have no idea ..." Worried about something falling on your head as you walk down the street? We've got something better. Thousands of asteroids the size of baseball stadiums - and larger - orbit the sun with trajectories that inter- sect Earth's path. Eventually, Earth will collide with every one of them - at impact speeds of at least seven miles per second. The smallest of that set are large enough to cause deadly tsunamis and trillions of dollars of property damage. [see the link/story following this one for details on the near-term threat posed by Apophis] A medium-size asteroid will devastate our culture as it disrupts food chains, transportation systems, the elec- trical grid, and the overall stability of what we call civili- zation. The largest among them - the size of mountains - will launch an assault on the tree of life that will extinguish more than half of all land and oceanic species. Worried about a hole in the ozone layer cased by pollu- tants? How about no ozone layer at all? Not too far away, in a neighboring galaxy, lies a prodigious stellar nursery, birthing stars of all sizes - small ones and large ones. At the top end of this range are stars that die spectacular deaths - exploding their guts at staggering speeds across the galaxy. A particularly deadly subset of these will focus nearly all their explosive energy into a narrow beam that's bright enough to be seen across the entire universe. The beam is so intense with life-hostile UV and X-rays that if it happens to aim at Earth, the leading edge of this radia- tion will deplete our protective ozone layer entirely. With- out this line of atmospheric defense, the radiation that fol- lows will pass straight through the atmosphere, sterilizing Earth's surface. Worried about falling into a hole in the ground? How about a black hole in space? If you fell into one of these, you'd never come out. The very fabric of space and time closes back on itself, preventing all escape. And as you fell - feet -first, let's say - the gravity at your feet would rapidly be- come much greater than the gravity at your head, forcing your body to stretch beyond comfort - beyond your body's capacity to remain whole. Your body would snap, as your lower half separated from your torso. Each of those two body segments then would snap into two more pieces, and so forth. But it gets worse. During your fall, the fabric of space and time gets narrower, effectively extruding your body parts like toothpaste from a tube. We call this form of death "spaghettification." Worried about a fender bender on the highway? Consider the impending collision between our beloved 100-billion- star Milky Way galaxy and our nearby cousin, the Andro- meda Galaxy. These are two beautiful spiral galaxies cur- rently minding their own business, yet they are hurtling toward each other through the vacuum of intergalactic space, with a closing speed of about 400 miles per sec- ond. We collide in about 6 billion or 7 billion years. Stars will not likely hit each other directly - space is too empty for that - but a gravitational free-for-all will ensue, with stars, and whatever planets orbit them, cast hither and yon in the cosmic equivalent of a train wreck. Worried about global warming redrawing Earth's coast- lines? How about no coastlines at all? In about 5 billion years, the sun will exhaust its stable supply of hydrogen fuel. In response, its inner regions will collapse, raise the core temperature, and ignite helium as the next fuel source. In the meantime the sun's outer layers will expand prodi- giously, engulfing the entire orbits of Mercury and Venus. As the sun continues to grow - as the sun's luminous surface gets closer and closer - Earth will get hotter and hotter. The oceans will come to a rolling boil, evaporate into the atmosphere, and lay bare the ocean floor. Our heated atmosphere will escape into space, as Earth's surface becomes a scorched wasteland. Worried about Earth running out of fuel? The cosmos shares a similar problem. As the universe expands, the concentration of energy within it gets weaker and weaker. Eventually all gas clouds that make stars will have made all the stars they can. All stars, beginning with the most luminous ones, run out of fuel entirely. With nothing to replace them, the stars you see at night begin to blink off - one by one - as the universe becomes cold and dark and desolate. The cosmos will indeed end. Not with a bang, but with a whimper. Have a nice day. ABOUT THE WRITER Neil deGrasse Tyson is an astrophysicist with the Amer- ican Museum of Natural History. He is author of "Death by Black Hole," and most recently, "The Pluto Files: The Rise and Fall of America's Favorite Planet." - - - end of article - - - - - - Apophis (originally posted 040109) - - - Fortunately, in the present day, humans are capable of detecting asteroids, and may, if the need arises, and the asteroid is detected soon enough, be able to protect the planet and inhabitants from a devastating impact. Such is the case with Apophis. Note -- in a couple of locations in the follow- ing article, references to myths are included, but since humankind doesn't believe in myths any more (well, many humans don't, but in the case of the surviving myths, like God, Allah, Satan, jinns, devils, demons, angels, Shiva, Vishnu, Jesus, Christmas, Easter, Mohammad, and the rest of the Jewish/ Christian/Islamic/Hindu pantheon of super- natural beings, many still do), like the god Apep, the uncreator, or the sun god Ra, or the number 666 being the mark of the beast, or biblical end time prophecies, or Friday the 13th being unlucky, certainly humans will be delighted when/if it is confirmed that Apophis has no chance of striking Earth. On the other hand, if it's determined that Apophis will pass through the gravitational keyhole and does have a chance of striking Earth, I suppose that myth-believers will view that as reason to believe in whatever myths they can prop up with that threat. Neil DeGrasse Tyson - Death By Giant Meteor Present forecast? -2- excerpts highlight those: "In 2029 [Friday, April 13, 2009] , it will pass within about 18,000 miles of Earth ... If Apophis passes at 18,893 miles above Earth, it will pass through a gravitational "keyhole" about half a mile wide, which would nudge it just enough to send it on a course for collision with Earth seven years later, on April 13, 2036 [Easter Sun- day]." Date information based on information in the following article -and- at the fol- lowing website: http://neo.jpl.nasa.gov/apophis/ - - - Flying Up to Meet Asteroids A proposed NASA mission to intercept an ill-omened rock in the sky http://tinyurl.com/meeting-asteroids-apophis - - - Excerpt [with inserts, not part of original article, in brackets]: [myths and facts regarding the risk Earth and its inhabitants face regarding Apophis on Friday the 13th of April in 2029, and on Easter Sunday, April 13, 2036] Partly to help explain solar eclipses, the ancient Egyptians had a story about the ser- pent god Apep, the Uncreator, who tried to swallow the sun god Ra as he crossed the sky. Apep -- the Greeks called him Apophis -- personified death, destruction and chaos. His opponent was the goddess Ma'at, who represented all that was light and truth. Now, a group of NASA scientists is hoping Ma'at will once again help humans ward off the harbinger of destruction. The MAAT satellite -- Measurement and Anal- ysis of Apophis Trajectory, a conveniently descriptive acronym -- is still just an idea. But if it's built, the modestly priced probe could help illuminate one of the solar sys- tem's most famous and most misunderstood asteroids. A few months after its discovery in June 2004, asteroid 99942 Apophis was briefly thought to pose a serious threat to Earth in either 2029 or 2036. But further calculations showed it is unlikely to hit the planet, unless it passes through a gravitational "keyhole" that might send it swinging Earthward seven years after its initial visit. This would be bad, explained David Morrison, director of the Lunar Science Institute at NASA's Ames Research Center at Moffett Field, Calif. Apophis is about 1,000 feet across and roughly the size of a 25-story building. The 1908 Tun- guska meteoroid, which caused a massive fire- ball and flattened a forest in Siberia, was about 10 times smaller and about 1,000 times weaker in terms of energy. "Where Tunguska would have destroyed a city, something like Apophis is rather worse. It would ruin your whole day," Morrison said. "That's big enough to destroy a state in the U.S., or a small country. It's not something that you would want to sit back and (ignore)." - - - [insert -- unmentioned, the fact that if it struck a large body of water, the resulting tsunamis would unleash hell on Earth to an area vastly surpassing the areas flooded in the 2004 post- Christmas tsunami disaster] - - - Thankfully, Apophis is not likely to hit Earth, but it's worth studying because it comes so close and there are many other asteroids like it, Morrison said. It does seem like a good starting point for missions to understand these sub-kilometer asteroids," he said. As of Saturday, March 21, there were 6,163 known near-Earth asteroids, about 770 of which are a dangerous half-mile in diameter or wider, according to the Near Earth Object Office at NASA's Jet Propulsion Laboratory. Their paths around the sun occasionally bring them across Earth's orbit. With enough warn- ing -- and so long as we know about the aster- oid's existence, we'd have some warning -- humans could send a spacecraft to a threaten- ing rock and kick it away by slightly altering its trajectory. The MAAT probe would be designed to match Apophis' orbit and tell us if we need to move it. More cost studies are needed before NASA has a price tag, but Morrison said the mission is intended to be relatively inexpensive, around $100 million. It will piggyback onto a satellite going up to a geosynchronous orbit, about 18,000 to 22,000 miles above Earth, and con- tinue until it hooks up with the asteroid. It won't land or crash, unlike previous asteroid missions such as Deep Impact, but it will shed some light on the space rock by flying in forma- tion with it. It would carry several cameras, a radio system and a laser range system to measure the dis- tance between MAAT and Apophis so scien- tists can determine the asteroid's mass and trajectory. "If we ever face one that will hit us, the first question they are going to ask is its trajectory. It's only in Hollywood that asteroids change orbit. Once you determine the orbit carefully, then you can predict where it will be in the future," Morrison said. Scientists hope a refined understanding of Apophis' path around the sun will erase linger- ing worries about its odds of striking Earth. "It would be nice to have a press conference and tell you for sure it's not going to happen," Morrison said. Scientists' level of certainty has varied wildly since the asteroid was discovered in June 2004. That December, observations from some ama- teur astronomers set off alarms at JPL's Sentry asteroid-watching program. Around Christmas 2004 -- when most of the world was reacting to an Earth-based disaster, the Sumatra tsunami -- the odds of Apophis hitting Earth in 2029 peaked at 2.7 percent, a frightening statistical possibility. The number was soon revised down after a flurry of observations; as of now, the chances of Apo- phis hitting Earth in 2029 are about 1 in 45,000. In 2029, it will pass within about 18,000 miles of Earth, well within the range of geosynchronous satellites, but scientists at JPL say its trajectory won't endanger the satellites. That's where it gets interesting, however. Earth's gravity will dramatically affect Apophis' orbit, leaving scientists to estimate where it will end up next. If Apophis passes at 18,893 miles above Earth, it will pass through a gravitational "keyhole" about half a mile wide, which would nudge it just enough to send it on a course for collision with Earth seven years later, on April 13, 2036. MAAT will provide more data to check these estimates and tell us whether we should do something to move Apophis from that keyhole using a solar sail, some added weight or a space tugboat of sorts. It's also a way to test a type of asteroid-tracker that might be really important someday. We don't know exactly where Apophis is going to go, but it's very unlikely that it will end up on an impact trajectory," Morrison said. "But it is a prototype of the type of object that we might have to deal with." Scientists at JPL are confident further observation will show Apophis will pass about 49 million miles from Earth on April 13, 2036, which happens to be Easter Sunday. That date is one of many numerological coinci- dences that have helped make the asteroid famous: For one thing, Apophis is Near Earth Object 99942 -- 999 upside down is 666, the "number of the beast," a number associated with the end-times prophecy in the New Testament chapter Revela- tion. It is expected to pass Earth the first time on April 13, 2029 -- a Friday the 13th. What's more, 2 + 0 + 2 + 9 = 13. Feeling unlucky yet? Maybe the probe named for goodness and light will be able to help illuminate this dark nomad of the sky. ... - - - end excerpt - - - - - - Astrophysicist warns of asteroid hitting earth Story By: Susan Davies Source: KOAA Published Thu Apr 02, 2009, 03:22 PM MDT Updated Thu Apr 02, 2009, 08:54 PM MDT http://tinyurl.com/neiltysonwarning-Apophis - - - Complete article: What if space experts determined that an asteroid was likely to strike the earth. Turns out it's not a question of "if" but "when." Astrophysicist Neil deGrasse Tyson is not only a meteor and planetary expert, he's a host of the PBS science favorite "Nova." He says one of the thousands of asteroids orbiting between Mars and Jupiter is on a course to come alarmingly close to earth. Apophis is about the size of the Rose Bowl. It's predicted to pass between the earth and its com- munication satellites on Friday, April 13th - 2029. It will be the biggest thing we've ever seen come close to earth. Dr. Tyson says it won't hit us, but if it orbits around on a particular trajectory - "Threading the keyhole" he calls it, Apophis will come around and "smack" us seven years later [on Easter Sunday, April 13, 2036] - if nothing is done to prevent it. He says it'll plunge into the Pacific Ocean, create a huge temporary hole and cause monster wave after monster wave that will devastate the west coast. [I wasn't aware that an actual location was even possible at this point, if the asteroid passes through the gravitational "keyhole", so I'm unclear what Dr. Tyson's statement is based on] Tyson says we can't let that happen. "I don't want to be the laughing stock of the galaxy and go extinct as a species because we didn't do something about it." Tyson attended the 25th National Space Symposium in Colorado Springs this week to accept the Douglas S. Morrow Public Outreach Award. He says it will take the cooperation of private and public space agencies and companies, and it will take funding to solve this challenge. But - he adds - we have time. - - - end of article - - - |
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