Ok, NASA wants us all to just calm down!
In this article, NASA debunks (or at least comments on) all the current 2012 scenarios. What interested me most was the comment:
“For instance, some theorists claim that from our point of view, the sun will cross in front of the plane of our galaxy on Dec. 21. However, the sun already does this twice a year, Yeomans said.
In fact, the sun will eventually cross the plane of our galaxy. However, the sun is about 67 light-years from the galactic plane, so it should take several million years to do so, Yeomans said. Even then, when our solar system finally does cross the plane, nothing special will occur, he added.”
Well, that does not fit with what I have said previously (see part 1). What I said was happening, as related to the Galactic Ecliptic, was something like this:
Which can be seen in many articles and diagrams on the Web, with another example given below.
I want to be correct in any statements that I make, so I did some further investigation of my own. First, NASA is right about the ‘apparent’ cyclical movement of earth through the Zodiac. In my defence, the Wikipedia link in part 1 of this series has been modified and no longer has any of the quotes I used earlier!
This 26000 year cycle is really the wobble of the earth itself that completes a cycle as shown below.
This wobbles the Galactic Equator of the planet relative to the celestial sphere.
This wobbles the Galactic Equator of the planet relative to the celestial sphere. On December 21, 2012 or Celestial equator will align with the Ecliptic (of the Sun). While interesting, it does in fact mean nothing.
This does not negate the fact that the Solar System does indeed ‘wobble’ up and down through the actual Galactic Plane. It just does so in a much larger time scale.
Right now, these sites say the Solar System is North of the galactic plane. Anywhere from 2 to 98 light years above the plane and moving farther away as we speak.
“The orbital motion is represented by the slashed large line. This motion has a speed of 217.215 Km/s, hence the Solar System takes 226 million years to complete one lap around the Galactic Nucleus.
The movement onward-backward the nucleus of the Milky Way is determined by the gravitational pull of the nucleus and the stars situated inner the orbital track of the Solar System and by the gravitational pull of the stars outer from the track of the Solar System. This movement has a speed of 20 Km/s.
The motion upwards-downwards the plane of the galaxy are influenced by the motions of the bodies that constitute the Solar System, including the motions of the Sun. The speed of this movement is 5-7 Km/s and comprehends about 20 light years.”
http://en.wikipedia.org/wiki/Milky_Way (From Wikipedia for what is is worth)
“The Sun is currently 5–30 parsecs (16–98 ly) from the central plane of the galactic disc. The distance between the local arm and the next arm out”
“Scientific studies indicate that the solar system lies several dozen light-years north of the galactic plane. What’s more, we are continuing to travel northward, away from the plane of our Milky Way galaxy, at some 7 kilometers per second.”
But also interesting from Universe Today is (and from the same site used above):
Comet Strikes Increase as We Pass Through the Galactic Plane
May 6, 2008
“When our Sun rises up out of flat plane of the Milky Way, it appears we might be less protected from intergalactic radiation and cosmic rays. Well, it looks like passing through the middle of the galactic plane might have its own share of risks: an increased number of comets might be hurled towards the Earth because of gravitational interaction with the densest parts of our galaxy.
Researchers at the Cardiff Centre of Astrobiology have built a computer model of the Solar System’s journey around the Milky Way. Instead of making a perfectly flat orbit around the galaxy’s centre, it actually bounces up and down. At times it can rise right up out of the galactic plane – getting 100 light years above – and then dip down below it. They calculated that we pass through the plane every 35 to 40 million years.
And this time period seems to match dangerous periods of impacts on Earth. According to the number and age of craters on Earth, we seem to suffer increased impacts every 36 million years. Uh oh, that’s a match.
In fact, one of these high points of comet activity would have been 65 million years – the same time that an asteroid strike wiped out the dinosaurs.
And here’s the bad news. According to their calculations, the Solar System will be passing through the galactic plane in the near future, and should see an increased risk of impact. Our risk of impact could increase 10-fold.”
Well some things match, some things don’t. We pass thru the Galactic Plane every 36 million years or so. I think this is well understood ( I see some consensus on this and our estimated speed of travel). It also agrees with size of the wobble (about 100 ly). This article states that we are in fact BELOW the plane moving north thru the plane ‘in the near future’. I am confused, but will keep looking!