One should realize our universe is made up of 27 percent of “Dark Matter.” It’s been proven to exist, but cannot be seen. Either light emanating from the source is too dim to be seen, or simply too far away. Chances are both are true.
In 2005, astronomers from Cardiff University discovery of a galaxy of almost entirely dark matter, 50 million light years away in the Virgo Cluster. VIRGOHI21 does not contain any visible stars. It was seen with radio frequency observations. From rotation profiles, scientists estimate this object contains approximately 1000 times more dark matter than normal, and has a total mass of about 1/10 our Milky Way Galaxy. Comparatively, the Milky Way has roughly 10 times as much dark matter as ordinary matter.
Astrophysicists typically know when dark matter exists. There is huge discrepancies between large objects determined from their gravitational effects, and the mass calculated from their "luminous matter"--or stars, gas, and dust. It was first postulated by Jan Oort in 1932 to account for the orbital velocities of stars in the Milky Way, and by Fritz Zwicky in 1933 to account for evidence of "missing mass" in the orbital velocities of galaxies in clusters.
Can we be sure we haven’t been fooled into believing in dark matter and dark energy? As two clusters, one the Bullet Cluster, passed through each other, the hot gas in each ran into the gas in the other, while the individual galaxies and the dark matter passed right through each other. Astrophysicists Doug Clowe, Arizona, and Maxim Markevitch, , Harvard-Smithsonian Center for Astrophysics, have compared images of the gas obtained by the Chandra X-ray telescope to “maps” of the gravitational field, in a short paper [astro-ph/0608407], and on lensing [astro-ph/0608408]. This provides huge amounts of dark matter to explain cosmological dynamics.
A clever gravitational lensing survey to search for clumps of dark matter in the halo of our galaxy began in 1992. The survey was designed to find MACHOs, (MAssive Compact Halo Objects), or "chunks of dark matter." Originally, MACHOs were believed to find failed stars or planets not emitting light. Instead MACHO recorded any dark matter with a mass between earth's and 10x the sun.
The astronomical evidence we have for dark matter ranges from within our galaxy, to the far-most regions of space. It‘s now understood dark matter dominates the galaxy. Whatever the dark matter is, its five times more present than ordinary matter. Now it’s thought dark matter is made of "Weakly Interacting Massive Particles", (WIMPs). This weak attraction makes WIMPs essentially invisible to ordinary matter. Billions of WIMPs may be flowing through your body right now without knowing.
The real question is, what may exist in dark matter we haven’t seen yet? Theories abound, but it’s a given there’s some heavenly bodies like rogue asteroids, invisible comets, miniature planets and general intergalactic debris hiding in dark matter. For all we know, if actual UFO’s exist, what could be a better place to hide than a location where no one looks?
But www.space.com explains how dark matter potentially slings lethal meteors at earth, causing mass extinctions like the cataclysm resulting in the dinosaurs’ fate.
Realizing a dense disk of dark matter 35 light-years thick lies along the central plane of the Milky Way, physicists Lisa Randall and Matthew Reece, Harvard University, have suggested meteor bombardment on earth occurs every 35 million years. Randall and Reese understood this cycle closely matched the sun passing through the Milky Way’s central plane. This signifies the galaxy's dark matter may be causing the asteroid bombardment and the disturbing of comet orbits in the outer solar system, hurling them inward. Previously mentioned Harvard scientists analyzed craters larger than 12 miles wide made in the past 250 million years, and compared their pattern against the 35-million-year cycle. They found it three times more likely those craters matched the dark matter cycle, than occurring randomly.
But how frequent are rogue asteroid visits? Actually, most asteroids go unnoticed because they explode in the atmosphere, before causing major damage on earth. Usually most impacts occur above remote parts of the ocean. Sometimes a powerful collision occurs over an area heavily populated by humans.
Now, Chelyabinsk, Russia marks where a 600-kiloton meteor impact occurred February 2013, damaging hundreds of buildings and injuring more than 1,000 people. "While most large asteroids with the potential to destroy an entire country or continent have been detected, less than 10,000 of the more than a million dangerous asteroids with the potential to destroy an entire major metropolitan area have been found by all existing operated observatories," said former NASA astronaut Ed Lu. "Because we don't know where or when the next major impact will occur, the only thing preventing a catastrophe from a 'city-killer' sized asteroid has been blind luck."
A brief video called catastrophic asteroid impacts on Earth shows locations of each of the 26 known asteroids hitting earth from 2000-2013. Thousands of asteroids pelt the earth every day, but usually burn up in the atmosphere, or splash unnoticed somewhere in the vast oceans. The atomic bomb destroying Hiroshima, Japan, exploded with a power of 15 kilotons of TNT. The 26 asteroids in the last 13 years exploded with a force of 1-600 kilotons. It’s also predicted once a century, there will be a comet big enough to destroy a city.
Anything’s possible in the next hundred years. Of course, next Tuesday may be more correct considering recent impacts.
Kevin Roeten can be reached at email@example.com.