Good example of observational evidence that accords with a theory's prediction, even if the theory does turn out to be incorrect.
This is beautiful:
"Recently, NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite made precision measurements of the imprint of sound waves on the cosmic microwave background, produced some 400,000 years after the big bang. Because sound propagation depends on the properties of the medium--as anyone who has played with a helium balloon knows--the pattern of the sound waves viewed by WMAP is an indicator of the abundance of hydrogen and helium in the universe."
i thought this particularly interesting -
"It is estimated that our solar system is passing through a fine sea of dark matter particles with a density as high as roughly 105 per cubic meter. We may hope to detect the flux of dark matter passing though the Earth, and even to detect the seasons of dark matter, corresponding to the times of year when the Earth is moving with, or against, the flow of dark matter orbiting the center of the Milky Way."
- because a couple of years ago I submitted a question to MadSci Network
Q: (May 23 2007) Does dark matter have a measurable effect upon the orbits of planets?
A: ...Dark matter doesn't impact the orbits of planets significantly. Because we don't know how to detect dark matter directly, it is hard to know its exact distribution. Most of the mass of local dark matter is located in a halo surrounding our galaxy (likewise for all other galaxies), but whether that means we are in an area devoid of dark matter or not isn't certain. But even if there is dark matter around us, its density would be both low and nearly uniform- imagine a thin gas made of dark matter. The orbits of the planets are dominated by the large mass concentration of the Sun (and to a small extent, Jupiter). Neither a thin gas of dark matter around us, nor the much greater mass found outside our visible galaxy, can affect planetary motion.
In short, "No"
..good example of observational evidence that accords with a theory's prediction..
Epicycle model of solar system can predict solar eclipses as well - it's just overly complex. But we can put a trivial question like inspector Colombo:
Why astronomers, who are looking for missing antimatter in Universe from the very beginning of BigBang theory (Lemaître 1931) haven't considered the posibility, dark matter may be composed of antimatter from the very beginning of dark matter observation (Fritz Zwicky, 1933). Why they're needing another unseen-yet particles to explain the presence of antimatter in dark matter by now?
I predicted this a two years before, just when I started to deal with AWT.
..does dark matter have a measurable effect upon the orbits of planets? In short, "No"
Not the orbits of large planets. But the leighweight ones are affected by the same way, like stars in gallaxies. Has someone heard of Alais effect or Pioneer spacecraft anomaly?
..it is estimated that our solar system is passing through a fine sea of dark matter particles with a density as high as roughly 105 per cubic meter.
The density of dark matter particles is at least thousandtimes lower. In fact it corresponds the density of positrons observed. But has someone heard of cold and hot dark matter?
Any ideas? Try to think creativelly for a moment. You can learn it only by praxis.