by Aldo Hugo Olguin
Prof. of Mathematics, Physics and Cosmography
aldohugoolguin@yahoo.com.ar
The light on the surface of our planet changes throughout the year as the Earth revolves around the Sun. This motion produces the different seasons, each one with its own characteristics. March 21st begins a new fall in our hemisphere, and a new spring in the northern hemisphere. On that day, the rays of the sun fall vertically on the Equator, and illuminate both hemispheres equally. There are 12 hours of darkness and 12 hours of daylight on Earth.
But, does only light come from the sun? Man has investigated this star and its influence on the interplanetary medium since Galileo’s times, about 400 years ago, when he warned us of the fact that the visible face of the Sun was not as pristine as it was once thought. Galileo explained that the sun presented dark spots that were visible to the naked eye when the Sun was near the horizon. Today we talk about SPACE WEATHER to point to the set of phenomena and interactions that take place in the interplanetary medium. This is mainly regulated by the activity that originates in the Sun, which affects both satellites and planets.
Geomagnetic storms that occur as a result of solar activity also influence the different forms of life. In Figure 1 (total solar eclipse), we see that the moon (the black circle) covers the solar disk, from where the light we receive from the Sun comes (the solar photosphere), and thus the irregular-shaped outer layer becomes visible (the solar corona). It is from this place that high-energy radiation comes from, as well as the huge bursts of hot plasma which is accelerated by the pressure of solar radiation into interplanetary space. These coronal mass ejections (Fig. 2) could, at some point, reach and penetrate the Earth's magnetic field, thus producing high-intensity currents in power lines, and leaving them unused in a few seconds - with the consequences this would bring to a highly technified society.
In 1859 a storm of this type put out of service the recently opened telegraph lines.
The NASA twin STEREO probes (Fig. 3) are currently photographing the Sun in three dimensions and monitoring the turbulent activity on its surface to predict the weather in space, as well as to record storms heading to different planets.
Our question: Can man take this gigantic energy for the benefit of mankind in the near future? This will certainly be the greatest challenge for those who inhabit the Planet Earth.
Enjoy fall as much as spring!
