Bring4th

Full Version: Some stuff happening on the sun
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
http://science.slashdot.org/article.pl?sid=10/12/24/034217

Quote:"While we are well along into solar cycle 24, there remains a significant gap between the predictions of where we should be, and where we actually are in the progression of the cycle. Recently, the sun went spotless again, and the solar Ap geomagnetic index, an indicator of the solar magneto, hit zero. It is something you really don't expect to see this far along into the cycle. In other solar news, scientists monitoring the SORCE solar satellite have found that solar ultraviolet emissions have dropped significantly in the past few years. The Solar Irradiance Monitor on the satellite 'suggests that ultraviolet irradiance fell far more than expected between 2004 and 2007 — by ten times as much as the total irradiance did — while irradiance in certain visible and infrared wavelengths surprisingly increased, even as solar activity wound down overall.'"
It is difficult to forecast how an intelligent entity such as the sun will act if you are looking at it from the perspective that it is just an energy equation.
What does this mean?
If you looked at what is being described in the article, that the irradiance is increasing in infrared and visible portions and decreasing at the ultraviolet portions, we can see that the distribution across the spectrum is changing, more of it is now at the lower frequencies.

For context:

Here is quote from the Wien's displacement law article in the examples section:

Quote:Light from the Sun and Moon: The effective temperature of the Sun is 5778 K. Using Wien's law, this temperature corresponds to a peak emission at a wavelength of 2.89777 million nm K/ 5778 K = 502 nm or about 5000 Å. This wavelength is fairly in the middle of the most sensitive part of land animal visual spectrum acuity. Even nocturnal and twilight-hunting animals must sense light from the waning day and from the moon, which is reflected sunlight with this same wavelength distribution. Also, the average wavelength of starlight maximal power is in this region, due to the sun being in the middle of a common temperature range of stars.

You then look at what is called Planck's law of black-body radiation (Wien's displacement law is similar), and this gives you the spread of the irradiance values for each wavelength/frequency along the spectrum, for a given temperature.

It gives you a graph such as this one attached.

Here we see that this implies that the temperature of the sun is increasing. Its distrubution is becoming more like the one plotted by the red line.

In terms of what that means for us, it means that less of what we get from the sun, in terms of thermal energy, is scattered by the earth's magnetic field in the upper atmosphere, as is what happens with ultraviolet rays.

So more of it reaches the surface as thermal energy, heat. So we have increased surface heating. Global warming/cooling..?? Remember that many of the planets in the solar syste are experiencing phenomena related to surface heating.

Another interesting, but more speculative point is that this extreme solar minimum (trough) seems to correlate with the sharp increase in mean global surface temperatures in the last few years.
What do you think? Peer review? Haha Smile