“medium” or “bridge of matter” between the Sun and the Earth. The importance of the solar wind is that it establishes a This is much lower density than typical vacuum experiments in Here we can see the flow speed out from the Sun, ranging from 450 kilometers per sec to 350Īverage of a few particles per cubic centimeter. There are a number of spacecraft out in the solar wind, monitoring its properties. A cartoon representation of it is shown below. The corona expands out into space to form a medium which isĮverywhere flowing away from the Sun. ![]() The reason this was notįigured out in 1869 was that at that time there was not technical ability toĪ tough but interesting question for you to think Line of an iron atom that had 9 of its 26 electrons stripped away (so-calledįrom iron with 13 of the 26 electrons removed (FeXIV). Measurements which became possible then that the “red line” was an emission Third electron out takes still more energy, etc. Takes more energy because the atom hangs on to its remaining electrons more The amount of energy required is called the ionization You can knock electrons out of an atom, if you put enough energy into it. Nucleus and 20 electrons in the neutral state, so an atomic number of 20. The element calcium has 20 protons in the ![]() Physicists and chemists call the atomic number). That the element iron has 26 protons in its nucleus, and an intact (electrically neutral) iron atoms has 26 electrons surrounding the nucleus (what The solution finally came in 1939, and was extremely interesting. For a long time, there was speculation that these emission lines might result from Of known elements that had been measured in the laboratory. While some of the emission lines were identified, others did not correspond to emission lines The coronal spectrum is shown below, which shows a little image of the Sun at a wavelength where the They found that the corona has an emissionĮmission lines at 530 nanometers (the Green Line) and 637 nanometers (the red line). Theįirst spectrum of the corona was made in 1869 by two American astronomers, Harkness and Young. The corona has a very interesting and puzzling property. The beautiful structuring of the corona is due to solar The solar corona, shown below, is one of the most beautiful objects in astronomy. “crown”) is the gleaming halo seen around the Sun at times of total solarĮclipse. Sun is that its edge seems so sharp, like a solid object, even thoughĪbove the photosphere lie the chromosphere and As mentioned last time, the temperature of the photosphere is 5800 Which comprises the opaque gases we recognize as the disk of the Sun. Mentioned that the three-part structure of the Sun’s atmosphere isĬrucial to understanding the nature of solar-terrestrial relations. We don’t have much of this radiation at the surface of the Earth is due to theĪbsorbing effects of ozone in the Earth’s atmosphere. Leaving organisms (the shorter the wavelength, the worse it is). In the ultraviolet part of the spectrum below 400 nanometers. Note also that the Sun produces a fair amount of radiation You can see that this is just where sunlight reaches its maximum ![]() Wavelengths between 400 and 700 nanometers. Remember again that the human eye is sensitive to light with Now let’s look at a graph of the spectrum of the Sun. ![]() Check pages 138 and 139 of the textbook.įor a demonstration of blackbody radiation, be sure to check the on-line video clips, or Last time I talked about the spectrum of the Sun, saying that it shines via blackbody
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