Astronomers detect a 62 million year cycle whereby the earth, instead of being part of the Orion Arm of the Milky Way, actually moves on a different plane entirely, I have talked about this in the past in several articles: the sun isn't native to this galaxy but rather, was born within a small 'hobbit' star cluster/galaxy which was captured by the bigger galaxy and we go through vast changes in our stellar environment as our sun moves through various parts of the galactic plane.
Mikhail Medvedev and Adrian Melott, both of the University of Kansas, presented their new theory at a meeting of the American Physical Society earlier this month.
The theory offers the first explanation for a mysterious pattern previously noted in the fossil record.
"There are 62-million-year ups and downs in the number of marine animals over the last 550 million years," Melott said.
One of the wonders of Nature is how things like to cycle. Cycling isn't straightforwards, it usually means circular motion or waves or things making waves by moving in circles, etc. If the movements of galaxies through time and space could be seen as if they are snakes moving across sand dunes, for example, we could then trace their paths. But of course, we cannot. We can only try to figure out from what we see to day, what happened in the past.
We can now plainly see thanks to modern optics, galaxies are sucked into each other's orbs and they merge quite violently. And 'active' galaxies are filled with very hot, white stars. We can see some really spectacular fireworks within some of our neighboring galaxies. The nearer to the source of these crashes, the hotter and brighter the stars. Our own star isn't hot and white, it is a yellow star and thus, has a long life.
Looking at other galaxies, I can only say, we are so fortunate that our little star has been captured by a galaxy that has only sucked in very small mini-galaxies and is not participating in one of those epic mass-collisions we see all around us.
From the National Geographic:
The Kansas researchers discovered that high rates of extinction in the cycle coincide almost perfectly with periodic "excursions" of the solar system outside the central plane of the Milky Way galaxy.
"Excursions to galactic north coincide with drops in biodiversity," Melott said.
During these periods, which include some of the largest mass extinctions known from the fossil record, Earth is bombarded with high levels of cosmic radiation.
Funny, that. Do all the hot, white stars take little strolls away from the general gravitational pool? I doubt this. We now can see that when various mini-galaxies or dwarf and hobbit galaxies fall into the gravitational grip of a big galaxy, they usually get stretched out with the family of stars losing contact with each other but since they fall in from all sorts of directions, they can even have polar orbits vis a vis the greater galaxy!
Our orbital plane is at a diagonal. Everything is somewhat cock-eyed vis a vis all the stars forming out of the interstellar dust and dirt that seems to be flowing in from all over the place. This dirty black stuff which doesn't emit light cloaks our galaxy so we barely can see any of the bright stars forming out of this mucky mess. The brutally bright core of this galaxy is nearly totally hidden from view or night would be as bright as day!
Since we are slowly being drawn into this galaxy and since it is also dragging in lots of dirt, as our little star, the Sun, rotates on its older path, it moves in and out of bands of space junk. These periods can be quite hazardous.
Our solar system travels through the disk-shaped Milky Way on a complicated circuit that takes about 225 million years to complete. At regular intervals, the system's wanderings take it up and down through the thin central portion of the disk. The sun reaches its farthest distance from the central plane every 62 million years.
The entire galactic disk, meanwhile, is hurtling through the hot gas that surrounds it at about 125 miles (200 kilometers) a second.
Wait! Wait! Is the Universe filled with 'hot gas'? Or are we in hot gas because we are part of a group of galaxies called 'the Local Group' (I love these utilitarian names!)? And the Great Attractor is attracting all this gas, right? And we are moving through it and not moving with it? What is this?
Looking at motion we have to remember our galaxy is rotating. In a circle. Like down a drain-type circle. In addition, we are moving towards the Great Attractor. Which I am assuming is rotating and moving probably in a circle, too. A big, big circle, of course. Anyway, our earth has been circling this star called the sun and it has been probably part of a small star cluster or mini-dwarf-hobbit galaxy and now we are trying to circle the Milky Way and we are off base because we are foreigners.
Life on our earth evolved in only 1 billion years. What if one of the companion yellow suns in our hobbit galaxy evolved life 3 billion years ago? Then they would have been the creatures who watched apprehensively as this quiet, peaceful group of old stars fell into the Milky Way and were torn from each other and exposed to vast explosions and disasters. Somehow, our own planet managed to survive. Occassionally, infalling material from that time passes by like we are seeing this week, zipping around the sun.
Seven of the new galaxies are gravitationally bound to the Milky Way, while the eighth appears to float freely in space.
The new Local Group members are even smaller and fainter than other known dwarf galaxies, with luminosities ranging from only a thousand to at most a few hundred thousand times that of our sun.
The dimness could be the result of stellar age, as seven of the new galaxies contain mostly old stars. Of these seven, two are located in the constellation Canes Venatici, one in Bootes, one in Leo, one in Coma Berenices, one in Ursa Major and one in Hercules.
Our eccentric orbit of this galaxy can't have gone on so close to the Orion Arm for 5 billion years. We would be much closer to the center by now if our sun formed while part of the Orion Arm. Since we glide up and down due to the spiral effect of our passage through space relative to the flatter plane of the Milky Way, note that few if any hot white stars get to have eccentric wanderings!---we go in and out of lots of different levels of density and gases of various sorts.
Probably our sun flared into existence out of the little galaxy it belonged to when the smaller galaxy began to suffer tidal pulls from the looming Milky Way. I bet that 5 billion years ago, if there were astronomers on this planet, they would have had a most spectacular view of this huge galaxy seen from a 32 degree angle!
Indeed, wouldn't it be logical that our sun hasn't always been in the Orion arm but has been in various other places vis a vis the rest of this galactic system? We don't know! Just like it took a long time for people to emotionally accept the idea that the earth went around the sun, so it is with our sun; it goes around the galaxy in an erratic way because it is alien.
A description of our local region within the Milky Way would not be complete without a mention of Gould's Belt. In 1879 the astronomer Benjamin Gould reported his survey of the distribution of bright stars in the local Milky Way. Gould's work showed that a true local subsystem of young stars and gas existed in a rotating flat disk inclined some 20 degrees to the proper disk of the Milky Way. The disk extends some 2000 light years across and contains some of the most famous astronomical objects including the Pleiades, the Orion Nebula and Horsehead regions, the California Nebula, the Coal Sack and the Rho Ophiuchus clouds near Antares. Gould's Belt must be a young structure between 30 and 40 million years old by virtue of the young stars it contains but its origins are still unclear. One theory is that an errant supercloud collided with a major spiral arm of the Milky Way about 100 million years ago. The shock wave resulted in the process of braking and compression of the gas of the supercloud into a flat rotating disk. The older stars drifted out of the disk leaving the younger stars to form Gould's Belt.
This could be problematic: I will note that thinking of this as an 'arrant cloud' that happens to 'collide' with our massive galaxy is funny. Wherever this cloud was moving in the past, once it came within the jurisdiction of the gravitational pool of this rotating galaxy, it rotated into it just like all the other junk that has added onto this system. Our sun is not a hot star nor was it very near any of these which is why I am assuming there wasn't much hot gas with the mini-galaxy our sun belonged to so when it was captured by the Milky Way, the impact was minor. As it is, when stars blow up or we get exposed to the violence of the elements burning around the galactic clusters that are flying through space towards each other, the grip that living things have on this planet are weakened badly.
Um, 4 billion years ago, our sun was born in this 'errant supercloud'. Stars born in smaller galaxies form groups. How shall I put it? Galaxies minding their own business, breezing along their ARC in the cosmos, sail along with old stars, all pretty much stable yellow guys along with assorted amounts of gases and thingies we call 'dust' and 'comets' and whatevers. Junk. And this largish mass with a non-blackhole center, namely, not very intensely organized but still enough gravity to form stars of middling size like our own sun, when two galaxies finally get within each other's tidal surges, they light up like a Christmas tree!
In a now-classic 1974 paper, Richard Stothers and Jay Frogel ["The Local Complex of O and B Stars. I. Distribution of Stars and Interstellar Dust," R. Stothers and J. A. Frogel (1974), Astron. J., 79, 456.* -- WebEd.] mapped out the spatial extent of the belt. Using newly determined distances for B5 and hotter stars, they found two highly flattened stellar systems inclined by 19° – 22° to each other -- the underlying galactic field and Gould’s belt. Figure 1 below shows an edge-on view from within the galactic mid-plane. The dots represent stars of spectral type B5 and earlier (hotter). The Sun is at the intersection of the X and Z axes, and the galactic centre is well out of the view to the right, 8,500 parsecs (pc) distant. The intersection of these planes coincides almost exactly with the position of the Sun. Actually, the Sun is about 20 pc above the galactic plane, but is, within the errors, precisely in the plane of Gould’s belt. The stellar density decreases with distance from the Sun because stars at greater distances are less completely sampled.
Astronomers like to imagine that if we have an increase in cosmic rays, mutations speed up and this causes extinctions. And I say, this is silly. Evolution needs mutations! This is what makes it run! But the force that creates changes in life forms is environmental. If old niches suddenly disappear because the weather changes, many life forms collapse or go extinct. And many, many have over the eons. Today, the earth is covered with life forms although humans are trying to destroy this.
When major extinctions happen that depopulate huge parts of the earth, this means habitat niches have changed in ways that living things can't deal with through simple mutation. Namely, even the mutants die. This happens when things get very hot or very cold, very fast. Since our sun is the main force that runs our energy systems, a sudden flaring of the sun because of gravitational disturbances vis a vis the Galactic plane, just for example, can cause the planet to overheat. Since sea extinctions are cyclic, this means we are probably seeing the sun's surge in energy on a 62 million year cycle?
If the sun is hyper-active, this means it probably spits out x-rays and the solar wind would be terrific and this would do bad things to the ozone layer too. And so it isn't the mutations but the generaly destruction of the environment that would be the killer. Namely, only select, protected communities can survive and of them, many are mutants and thus, the older life forms don't show up exactly as they were before.