The Sun has been ‘in the news’ these days. You may have read about various phenomena associated with the Sun, including sunspots, flares, and auroras or Northern Lights. So why all the interest in the Sun now?
We now know that everything we observe on the Sun’s surface is connected to its magnetic field.
Note that the Sun does not really have a solid surface. The hydrogen fusion reaction at the core of the Sun occurs at extremely high temperatures and the only form of matter that can exist is plasma, ionized gas. The Sun rotates just like the Earth. The combination of charged plasma and rotation produces the solar magnetic field.
Unlike the Earth which is rocky and, hence, has a consistent stable magnetic field flowing between the North and South Poles, the solar magnetic field is chaotic and highly energetic.
This field produces all the phenomena mentioned above and more. However, sunspots were the earliest phenomena observed from Earth.
The existence of sunspots was first documented in 364 BC by a Chinese astronomer. There is evidence in the Chinese i-Ching that suggest they knew about sunspots even as early as 800 BC. However, the first quantitative data on the sun was the number of sunspots that occurred each month. The data was first collected in the 17th century AD, using refractor telescopes that projected the sun onto a white surface.
Several hundred years of sunspot observations have produced data that show the Sun has a cycle of about 11 years. The peak of the cycle is solar maximum, and the valley is solar minimum. Solar maximum for the present cycle will occur sometime in the next year. Like the stock market, we cannot determine the maximum or minimum until after each happens.
We observe an increase in several solar phenomena as the Sun approaches maximum. These include stunning prominences (eruptions of plasma from the surface that appear in many shapes, e.g. arches, curtains), flares (explosions on the Sun of short duration but extremely high energy), and coronal mass ejections or CMEs. If a CME is ejected towards the Earth, the charged particles ejected by a CME interact with the Earth’s magnetic field and atmosphere, causing auroras. CMEs and flares often occur together and can disrupt communications and electrical equipment on Earth and can present a hazard to astronauts, requiring them to shelter inside their spacecraft or the ISS.
You have been listening to “Western Slope Skies.” Music written and produced by Kenny Mihelich (ma-HELL-itch). Content produced by members of the Black Canyon Astronomical Society and KVNF Community Radio. I’m Bryan Cashion.
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