Energy from the Sun

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Phobos
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Joined: Thu Oct 19, 2017 2:54 pm

Energy from the Sun

Post by Phobos » Fri Feb 16, 2018 9:10 pm

Hi again, I was looking through some notes that I'd taken from a book about the Sun (can't remember name of book now) Apparently, measurements from spacecrafts have shown that during solar minimum, the Sun becomes overall slightly fainter. So if we're heading for a GSM, does this mean that it will get even more cold than a 'normal' minimum. And we'll receive less light from the Sun? ALso, I've read that the magnetic field of sunspots was declining by about 50 gauss per year during solar cycle 23 and has continued to weaken during this cycle. I take it that both these occurences are connected?

Thanks for any help!

airdrop
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Joined: Sun Feb 18, 2018 1:57 pm

Re: Energy from the Sun

Post by airdrop » Mon Feb 19, 2018 4:23 am

They must be busy lol , if you want people to hang you'll need to be a bit quicker . From what I've read this minimum will be quit low and lead to some major discomfort as it effects food production and weather patterns . Get ready friend >

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lisa
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Joined: Tue Oct 10, 2017 6:28 pm

Re: Energy from the Sun

Post by lisa » Tue Feb 20, 2018 10:41 pm

Hi Phobos!

Once again, great questions! My apologies for the late response, but I was out of town for the weekend.
Apparently, measurements from spacecrafts have shown that during solar minimum, the Sun becomes overall slightly fainter. So if we're heading for a GSM, does this mean that it will get even more cold than a 'normal' minimum. And we'll receive less light from the Sun?
The measure of the energy output of the Sun is referred to as the Total Solar Irradiance, or TSI. Here is a plot of TSI over the last few solar cycles:

Image

As you can see, there is a solar cycle modulation of the TSI. However, I want to draw your attention the the units, you'll notice that the TSI only varies by a fraction of a percent over the course of the solar cycle (e.g., from maximum to minimum). In fact this variability is so small, that the TSI was historically referred to as "The Solar Constant" because the variability was so small that scientists weren't able to resolve the variability and once thought that it was constant.

As to the coming solar cycle, it is on track to be a bit weaker than Solar Cycle 24 (my prediction will be coming to SCS soon, but I did get a bit delayed with it), but more akin to a Dalton type minimum (cycles 5&6, 1800-1820, see https://upload.wikimedia.org/wikipedia/ ... e_1750.png) than a GSM. Unfortunately, we will have to wait another 10-12 years (until we get through most of SC25) before we can say whether the Sun will recover, like it did for SC7, or if we will go into a deeper minimum.

For more information about this and how the solar cycle variability impacts the Earth's weather, I encourage you to check out these sites:
https://www.nasa.gov/mission_pages/Glor ... iance.html
https://science.nasa.gov/science-news/s ... sunclimate
https://www.carbonbrief.org/why-the-sun ... ate-change

ALso, I've read that the magnetic field of sunspots was declining by about 50 gauss per year during solar cycle 23 and has continued to weaken during this cycle. I take it that both these occurences are connected?
The magnetic field in sunspots has been declining, but this is mostly due to do the fact that the strength of the solar cycles has been declining since SC23. Weaker cycles to produce weaker active regions on average. (However, even a weak cycle can produce a monster AR - e.g., Cycle 24 produced AR12192 which was the largest AR in 24 years and the 33rd largest on record.) Though larger spots appear as dark region in the visible light spectrum, they tend to to produce much more energy and light in EUV and Xray portion of the spectrum, so indeed they are connected!

Cheers!
-Lisa

Phobos
Posts: 34
Joined: Thu Oct 19, 2017 2:54 pm

Re: Energy from the Sun

Post by Phobos » Wed Feb 21, 2018 8:49 am

Thanks Lisa for this very in depth response. I know you're very busy. I'll check out the links you gave. Hopefully, it will only be a Dalton Mininmum and not a Maunder!

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