The discovery of exoplanet Sedna and its strange orbit is just one recent piece of evidence that supports this theory. The theory is that we cannot see or detect our second sun, which ranges only 1 to 3 light years away locked in an elongated elliptical orbit around the black hole. Our Sun’s sister star will supposedly peek out from behind the black hole, for a brief period of time, during the galactic alignment.

Following the logic of this theory, the mass extinctions by “Comet Showers” is made possible, by the Sun’s twin star when the two come into closer proximity around the center causing an intense gravitational disturbance of the Ort Belt , home to trillions of comets. During that time period the solar system would be careening with comets. (Time to stop focusing on Homeland Security and start revving up our Home Planet Security)

A big proponent of the binary star theory is The Binary Research Institute. http://www.binaryresearchinstitute.org

bugger.

It is also associated with a period of severe volcanism which formed the Deccan traps.

http://en.wikipedia.org/wiki/Deccan_Traps

“The bulk of the volcanic eruption occurred at the Western Ghats (near Bombay) some 66 million years ago. This series of eruptions may have lasted fewer than 30,000 years in total. The gases released in the process may have played a role in the Cretaceous–Tertiary extinction event, which included the extinction of the dinosaurs.”

Bias disclaimer: I’ve always sort of suspected that most attempts to correlate mass extinctions with periodicities are trying to put predictability on what are basically random events, so I’m inclined to be perhaps more skeptical than most.

Me two. While the famous K/T mass extinction is correlated with and may have been topped up by an impactor, apparently there are indications that continental and sea changes from continental drift softened up the ecological systems beforehand.

The usual and perhaps more likely suspects of large species and pathogens easily immigrating and wreaking havoc. If so, the underlying supercontinental cycle have a much larger periodicity than the extinction events, so such causes are contingent.

Add to that fact that mass extinctions are depending on definition, and it should be hard work attributing each extinction to a periodic factor.

It is an interesting but not especially scaring subject. While on the one side life has weathered a large number of extinctions, on the other we currently live in what could be the fastest extinction event ever. That doesn’t seem to cause people to loose much sleep. But impactors gets us “Armageddon” on the screen…

Aggrieved book buyer: I spent $$$ on this book and the world hasn’t been destroyed once already!

BA: Ah, but that’s just because I didn’t mention the way the world will be destroyed! Buy my next book for the real deal!

ABB: Oh, no, I’m not throwing good money after bad. You’ll have to destroy the world on your ownsome. I can’t afford it.

(Of course, if the world is destroyed, I’d be happy to buy any sequels you care to write.)

The mass of the asteroid is about right for a 40m sphere a few times the density of water.

28000 mph translates to 10^4 m/s giving an energy of around .5×10^17 joules.

1 kiloton is 4×10^12 joules so the asteroid has about 10^4 kilotons of kinetic energy.

Little Boy yielded about 15 kilotons so the asteroid is about 650 Hiroshimas.

I think I have some Bad Astronomy here …
http://www.guardian.co.uk/science/2008/may/07/starsgalaxiesandplanets.spaceexploration

Apparently a 40m diameter asteroid travelling at 28000mph and weighing 1.1m tonnes has the destructive energy of “84 Hiroshimas”.

My gut tells me right away that this is orders of magnitude out. So sure am I of my gut that I’m going to post this first and then I’m going to go away and work out if I’m right

I’m pretty skeptical about the relative weakening of the Milky Way’s magnetic field across a vertical distance of only 100 light-years since the thickness of the galactic disk in terms of stars is something like 1,000 light-years. I haven’t been able to find much on the galactic magnetic field, but for what it’s worth:

http://www.scholarpedia.org/article/Galactic_magnetic_fields

“Magnetic Field in the Milky Way -
According to radio synchrotron, optical polarization and Zeeman splitting data, the average strength of the total magnetic field in the Milky Way is about 6 ?G near the Sun and increases to 20-40 ?G in the Galactic center region. Radio filaments near the Galactic center and dense clouds of cold molecular gas host fields of up to several mG strength (Heiles & Crutcher, in Wielebinski & Beck 2005). Outside the central region, the large-scale field is mostly parallel to the plane of the Galactic disk. Faraday rotation measurements from the polarized radio emission of pulsars with known distances allow to investigate the structure of the Milky Way’s magnetic field in three dimensions with much higher resolution than in external galaxies. The overall field structure follows the optical spiral arms, like in other galaxies, but additionally one large-scale field reversal in the disk, inside the solar radius, and several distortions near star-forming regions were discovered (Wielebinski & Beck 2005). More large-scale field reversals in the disk have been proposed, but need confirmation by improved observations.”

So in the vicinity of the sun the galactic magnetic field strength is 6 millionths of a gauss. In comparison the geomagnetic field strength at the earth’s surface is about 0.5 gauss or 80,000 times stronger. I’m not sure what the galactic magnetic field lines are supposed to do. Sure, charged cosmic ray particles (mostly protons) will spiral around them but if the earth is in the path of one of these spiral trajectories it’s going to get hit anyway. Unless there is some confinement mechanism similar to the Van Allen radiation belts at work I don’t see how the galactic field helps us that much.

I’m pretty skeptical about the relative weakening of the Milky Way’s magnetic field across a vertical distance of only 100 light-years since the thickness of the galactic disk in terms of stars is something like 1,000 light-years. I haven’t been able to find much on the galactic magnetic field, but for what it’s worth:

http://www.scholarpedia.org/article/Galactic_magnetic_fields

“Magnetic Field in the Milky Way -
According to radio synchrotron, optical polarization and Zeeman splitting data, the average strength of the total magnetic field in the Milky Way is about 6 ?G near the Sun and increases to 20-40 ?G in the Galactic center region. Radio filaments near the Galactic center and dense clouds of cold molecular gas host fields of up to several mG strength (Heiles & Crutcher, in Wielebinski & Beck 2005). Outside the central region, the large-scale field is mostly parallel to the plane of the Galactic disk. Faraday rotation measurements from the polarized radio emission of pulsars with known distances allow to investigate the structure of the Milky Way’s magnetic field in three dimensions with much higher resolution than in external galaxies. The overall field structure follows the optical spiral arms, like in other galaxies, but additionally one large-scale field reversal in the disk, inside the solar radius, and several distortions near star-forming regions were discovered (Wielebinski & Beck 2005). More large-scale field reversals in the disk have been proposed, but need confirmation by improved observations.”

So in the vicinity of the sun the galactic magnetic field strength is 6 millionths of a gauss. In comparison the geomagnetic field strength at the earth’s surface is about 0.5 gauss or 80,000 times stronger. I’m not sure what the galactic magnetic field lines are supposed to do. Sure, charged cosmic ray particles (mostly protons) will spiral around them but if the earth is in the path of one of these spiral trajectories it’s going to get hit anyway. Unless there is some confinement mechanism similar to the Van Allen radiation belts at work I don’t see how the galactic field helps us that much.

http://palaeo.gly.bris.ac.uk/Essays/wipeout/default.html

A major catastrophe 251 million years ago left life teetering on the brink of oblivion. Now for the first time we have a clear picture of what caused it, says leading palaeontologist Michael Benton

251 MILLION years ago, at the end of the Permian period, life on Earth was almost completely wiped out by an environmental catastrophe of a magnitude never seen before or since. All over the world complex ecosystems were destroyed. In the sea, coral reefs, fishes, shellfish, trilobites, plankton, and many other groups disappeared. On land, the sabre-toothed gorgonopsian reptiles and their rhinoceros-sized prey, the dinocephalians and pareiasaurs, were wiped out forever. Only 5 per cent of species survived the catastrophe, and for the next 500,000 years life itself teetered on the brink of oblivion. What terrible event could have wrought such havoc?

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So you want us to hold of buying until the second edition comes out?

Do we even know if the strength of the galactic magnetic field is uniform? I vaguely recall reading somewhere that it’s stronger North of the Galactic plane then the south. Perhaps there are areas with protective bubbles that we have yet to map.

Also, random thought: at what point are we experiencing hostile conditions so frequently that we can’t really blame these for mass extinctions? If we’re getting abused when we’re in or out of the galactic disk, that almost seems as if it points to a more constant extinction rate, not punctuated massive die-offs. (Bias disclaimer: I’ve always sort of suspected that most attempts to correlate mass extinctions with periodicities are trying to put predictability on what are basically random events, so I’m inclined to be perhaps more skeptical than most.)