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Well if the angle of the ecliptic to the galaxy was changed from 90 degrees to 60 degrees, that would make the animation correct as far as movement with in the galaxy. But since it shows 90 degrees, then no, it's not correct.
Originally posted by PatrickGarrow17
reply to post by Arbitrageur
Is the general pattern of motion not correct, though?
The orbital speed of the Solar System about the center of the Galaxy is approximately 251 km/s.
Milky Way speed relative to CMB rest frame 552 ± 6 km/s
You will probably never see one which is completely "accurate". Why? Because people are interested in the Earth which usually isn't even visible in any accurate model of the solar system you'd put on a video monitor. This class exercise illustrates some of the scale problems with making an accurate model:
Originally posted by osirys
reply to post by Arbitrageur
I didnt even think about the fact that the galaxy was moving to. It would be interesting to see an accurate extended animation that shows the movements of the solar system, and the galaxy.
Then when you expand the scale to include the huge motion of the sun through space, everything gets even smaller.
Another area of difficulty for students is the relative sizes and distances involved. The radius of the sun is approximately 218 times as large as the Earth, so any visible scale model of the Earth will not fit on the same page or computer monitor image as the Sun. You can simulate this with a ball with a 2 cm diameter (e.g. a large marble) to represent the Earth , then, ask students to figure out the size of ball they need for the sun. (It would need to be 4.36 meters in diameter). Then, using the same 2 cm diameter marble to represent the Earth, ask how far away the center of the sun should be. (It would need to be 234.81 meters away - more than two football fields laid end to end!) So the students cannot create a scale model, but must instead adjust the scale to fit the display medium while maintaining visibility of all features.
Originally posted by trollz
Uh... I'm kindof confused here. What exactly about this was amazing? Did people not know that planets revolve around the sun or that they're all moving in space? I thought this was common knowledge.
Originally posted by Sly1one
in a 2d view (from the side) its a "wave"...in a 3d/4d view (from side) its a helix. This was NEVER taught to me in school and I'm pretty upset that it wasn't...I feel lied to because obviously the flat 2d from above model is absolutely inefficient at explaining the motion of our planets...the helix model helps explain what is happening so much better.
Originally posted by Soylent Green Is People
Any point on a rotating circle (like an orbiting planet) will trace out a sine or cosine wave over time.
For example, imagine an LED light bulb on the sidewall of a car tire at night. When the tire starts turning, you could say that the light would go around in a circle. However, think about that car driving away from you. the path the light would trace out would be a sine wave, NOT a circle.
Here is a website that has an application (a java-app) showing this sine wave movement:
Sine Wave Geometry
Originally posted by Sly1one
reply to post by osirys
I feel lied to because obviously the flat 2d from above model is absolutely inefficient at explaining the motion of our planets.
Originally posted by wildespace
Originally posted by Sly1one
reply to post by osirys
I feel lied to because obviously the flat 2d from above model is absolutely inefficient at explaining the motion of our planets.
How is it inefficient? It's efficient enough for us to predict the planets' positions for hundreds of years ahead (relative to the Sun or the Earth, of course) or to send robotic spacecraft to them. Planets in the Solar System move under the Sun's gravity. Motion through the galaxy has no practical effect on them (unless we pass very very close to a star).
Teaching the heliocentric model is not lying.
P.S. I'll correct that: scientists used 3D model, but centered on the Sun or the Solar System barycentre. The 2D model is a simplification that can be sufficient for many purposes, just like representing the orbits as circles when they are actually ellipses.edit on 28-9-2012 by wildespace because: (no reason given)
Originally posted by Sly1one
It may not be "lying" but I don't know why you wouldn't also teach your students about the other models...its like they did the circular model and left it at that, knowing damn well that is not the full picture...One model correctly describes our movement through space and the other only describes part of it and from a perspective by which there is an illusion the sun is stationary...