Answer:
26000 years
Explanation:
Precession describes the angular motion of the Earth's body. Since the attitude of telescopes relative to the Earth's body can be controlled with high accuracy, and telescopes can measure the direction of incoming light also with high accuracy, the motion of Earth is under permanent high precision monitoring. Thus the basic numerical descriptor of precission, an angular rate of 5029.0966 seconds of arc per Julian century, traditionally denoted p (for precession) is a measured value from observed coordinate changes of thousands of stars over, say, two centuries. The understanding of this value in terms of forces acting on an oblate Earth from the Moon is well understood so that an extrapolation back and forth over a few full cycles contains little uncertainties. Of course, you can find details on the coordinate transformations mentioned above (the direct observational effect of precession) on the net. I was surprised to see that the Wikipedia article on precession covers the astronomical aspect very poorly. You thus better look for other sources.
Answer:
Explanation:
The number of neutrons is 127 and the number of protons will be equal to number of electrons. It has 83 protons and a magic number of 127 neutrons. Bi 210 is radioactive isotope of bismuth.
<span>The "scientific method" consists of forming a hypothesis (a statement about what the researchers think is true), collecting data that might confirm or refute the hypothesis, and then examining the data to see how well or poorly they support the original hypothesis.</span>
Answer:
When an object vibrates, it causes movement in surrounding air molecules. These molecules bump into the molecules close to them, causing them to vibrate as well. This makes them bump into more nearby air molecules.
Solids wall cement chat door tree
liquids oil ,water ,saline solution,soap
gases. tear gas meathian gas steam
