What are Sunspots

The Sun

The Sun is a star at the very center of the Solar System. It is consistently orbited by planets, asteroids, meteoroids and comets. It emits light and heat that not only supports all life forms on Earth, but also offers the planet a climate and weather that is conducive to growth. This central star comprises hydrogen, helium, iron, nickel, silicon, sulfur, magnesium, neon, oxygen, carbon, chromium and calcium. The Sun has a surface temperature of approximately 5,500°C. When seen from the Earth, it seems to emit a yellow glow, which is actually white and appears so on account of 'atmospheric scattering'. The Sun is a 'main sequence star' that generates solar energy by a hydrogen-helium nuclear fusion. The Sun completes one revolution within the Milky Way galaxy in approximately 250 million Earth years or one Galactic year.

What are Sunspots?

The magnetic activity on the Sun's surface inhibits convection. This results in the formation of surface areas that have reduced surface temperature. These surfaces are visible from Earth even without a telescope and are referred to as sunspots. Sunspots have temperatures of approximately 4,500 K, within the surrounding 5,800 K. This makes them appear as dark spots due to the heat variation. Interestingly, research reveals that if a sunspot is viewed isolated from the photosphere around, it would actually be very luminous. A sunspot cycle roughly comprises eleven Earth years. The cycle refers to the number of sunspots due to recent magnetic polarity that outnumber the previously generated polarity variants.

Sunspots are breeding ground for secondary phenomena like sequenced reconnection events, coronal loops, solar flares and ejections or emissions of coronal mass. The same phenomena observed on other stars is referred to as starspots. The Sun is now observed to be at a heightened sunspot level, correlating to the intensity of solar radiation and radiative flux. Research suggests that an increase in sunspots could lead to lower solar radiation and solar constant or brightness of the Sun. Scientists are now exploring the possible resonant gravitational link between photospheric and inter-planetary tidal forces.

The earliest references to sunspots were made as far back as 28 BC, by Chinese astronomers. History reveals that a large sunspot was sighted at the time coinciding with the death of Charlemagne, in 813 AD. However, the most precise and well-interpreted explanations were not provided until 1612, by Galileo. The observations that Galileo Galilei worked on came from astronomers Thomas Harriot, Johannes and David Fabricius. Sunspots fuel the debate over the inherent nature of our solar system. The spots observed highlight the fact that the Sun does change and its appearance and generated radiation are subject to the motion of encompassed components.

Sunspots display cyclic variation of number and intensity. The relationship between sunspots and the Earth's weather remains a matter of continuous research and debate. Suggestions imply that:

• Sunspots do influence crop yields and hence, the economy.
• The Sun has changed modality from a period of little or no sunspots to regular sunspot cycles.
• Sunspots are counterparts of tubes of magnetic flux in the Sun's convective zone, caused by differential rotation.
• The spots observed are sun-surface depressions, ranging from central umbra, to the surrounding penumbra.
• Sunspots display a powerful downdraft, generating a rotating vortex.
• They are self-perpetuating storms like the terrestrial hurricanes we observe on the planet.

Sunspots can be observed with the help of terrestrial solar telescopes as well as those fitted on orbiting satellites. The generated filtration techniques involve the use of special-filter cameras, spectroscopes, hydrogen-alpha narrow bandpass filters, aluminum coated glass attenuation filters and spectrohelioscopes. Observation with the naked eye is known to cause permanent damage to vision.