Randall
This could be a nice topic to discuss, although I doubt there are people in the "Earth Science" forum that are versed in Astronomy and scientific methodology --at least to the extent as to mantain a reasonably coherent conversation. You see, this forum is full of people who believe in witches, blind sheeps and pregnant men in the Philipines... and their posts are more likely to be religious pamphlets or Apocalyptic prophecies than serious scientific disussions.
Anyway, let's give it a try. Although I do quite nice in mineralogy, physics, chemistry, biology, climate sciences, etc, astronomy or cosmology are my weakest points. Also, I have to apologize for my English writing, spelling, grammar and syntax, as I am a Spanish speaking person, so I beg you to forgive some mistakes I will make in my posts. One thing I would like to ask you is to confirm is "kpc" (related to astral distances). Is this the English abbreviation of "<b>kilo parsec</b>" (parsec = per second) that is, "thousand-year-light", the distance traveled by light in one year? In that case, am I wrong if I say it should be abbreviated "<b>kps</b>" --kilo per second? Excuse my ignorance in this field, and please correct me if I am wrong.
Then, although your theory seem feasible (and promising), I am not in possesion of the knowledge to even arguing with you about it. But, as my climatology studies gives me information on the field of warming, cooling, ice ages, etc, I would like to point you some facts.
Of course, the only thing that affects the temperatures on Earth is the sun --and related matters as tilt of Earth's axis and precession of the Equinoxes, and, given that these things have not changed significantly for the last 10,000 years, we can say that if the Earth warms or cools is due to <b>only two things:</b> a) The sun gets brighter or dimmer (solar cycles, sunspots, flares, etc), or b) The atmosphere gets filled with some obstruction, as dust (either cosmic as in your theory, or coming from the impact of asteroids big enough to send billions of tons and water up into the stratosphere.
We can dismiss the influence of "greenhouses" gases as CO2, methane, and other minor constituents of the atmosphere, because: 1) water vapor is the only major greenhouse gas (95% of heat retention capability), and 2) during the Cretaceus period (about 90 million years ago) concentrations of CO2 were in the order of 2,600 to 6,000 ppm, while global temperature was only 1,5°C higher than today. Greenhouse gases dissmised.
The <b>Medieval Warm Period</b> reached its highest point around the year 1200 AD, and about 1250 AD beagn a fast cooling. The line of the 15°C mean temperatures was crossed about 1350 AD, and kept going down until 1450 AD, when a slight warming was experienced. Around 1500 the world cooled quite fast until 1650 AD (when temperatures were at their lowest in the milennium). Then, a quite fast warming ocurred until 1700, and then, temperatures kept almost steady until 1860. From then on, temperatures have been returnig to the values they had back in 1200 AD --<b>but we still are 2°C below</b> those temperatures.
The arrival of "cosmic dust" from the Crab around 1250 could have helped to trigger the <b>Little Ice Age</b> (don´t let "global warming" environmentalists hear you say there was such an Age, because they will crucify you -- if you are researching with government funds you will lose your grants). I said <i>"it would help trigger"</i> the Ice Age because between the years 1300 AD and 1500 AD there happened the <b>"Spoerer Minimum"</b> cool period, when the absence of sunspots was almost total.
When the effects of the "cosmic dust" was likely to have disappeared (the dust had settled) and tenperatures began to go up again, there came the "Maunder Minimum" period of no sunspots, that lasted from 1640 AD to 1710 AD, when there were no sunspots at all. The sun had a period of absolute calm during those years, so the Earth cooled again. As the sunspot record began about the 1600s, what happened with solar activity remains a mystery --only partially solved (or attempted to solve) by "proxy" studies. By 1715, the solar activity became "normal" again, and Earth started to warm until these days. I quoted "normal", because the <b>only normal thing</b> known in Earth's history is precisaley <b>the changes that characterizes Earth geological and climatic record</b>.
Summing up: If the dust from the supernova reached Earth, it could have helped trigger the Little Ice Age, but the major "responsability" --in my humble opinion-- lies in the Spoerer Minimum, because when 150 years later the Maunder Minimum came along, it happend the same thing (and worse, because it cooled much more), while the effect of the cosmic dust must have disappeared by then.
The eruption of Tambora volcano set the world into a two-year "summerless" period, back in 1816 (even Ben Franklin wrote about it, blaming the weird weather on the Tambora). Given that the amount of dust received from space might have been greater than Tambora's ouput, I would accept that it could have cooled (or helped to cool faster) the world. But the dust and debris from Tambora have settled down after two years, so the dust from the Crab could not last much longer. How much? Ten years? Who knows?
But if there was enough dust to provoke such severe cooling, I suppose that must have been noticed by the people all over the world, and there would be written or oral accounts of an event so big that set Earth into a glacial age. If there are accounts of the vikings colonizing Greenland and Canada by the same time, then why are not there accounts of this cataclismic event? Or perhap´s there are? Or perhaps it went unnoticed down here at the surface, and everything happened up there, as you say: <i>"... two things would happen: pressure from sunlight would direct it away from the Sun, and collisions of the dust particles with solar photons would cause the particles to lose energy and transverse momentum. Some of the particles would end up spiraling into the Sun. But some of them would end up orbiting it. As the dust approached the Earth (some of the dust would be captured in an orbit just outside the Earth's), it would be perturbed by the Earth's gravity, and some of the particles would be sucked in."</i>
Could it be that the effects of the supernova <b>affected also the sun's activity and provoked the Spoerer Minimum?</b> Could be, why not? But then, what provoked the Maunder Minimum? Another supernova explosion? That show us there is too much we ignore about almost everything. And that makes life enjoyable: <b>the quest for knowledge.</b>
Let's keep with this topic. We might not end up earning lots of money, but we might end up "saving the planet"... whales, mosquitoes and butterflies included.
