After several years of quiet with a “deep minimum” in 2009 in its 11 year cycle, the Sun is now waking up, with colossal energies breaking through the surface in areas seen from the Earth as SUNSPOTS.
If you were lucky to witness the event of century, the “Transit of Venus” event on June 6, and saw the tiny dot of Venus crossing the face of the Sun, then you can easily see the sunspots that can be nearly six times bigger than that dot of Venus.
Sunspots can be seen during the daytime using a pair of solar glasses or by projecting the image of the Sun through a simple telescope, such as a Galileoscope, or through a pinhole. The pictures shows the setup of the Galieoscope and sunspots that I viewed, compared with the that from the NASA website www.spaceweather.com (the Galilescope image is inverted by the telescope lenses)
Sunspots are huge areas (up to 100,000 km across) on the surface of the Sun that are about 2,000 degrees centigrade cooler the rest of the surface of the Sun, which is around 6,000 degrees centigrade. Since visible light is only emitted around 6,000 degrees centigrade, the sunspots produce infrared radiation which our eyes cannot see. Hence the spots appear completely dark compared to rest of the extremely bright surface of the Sun.
Sunspots are areas through which extremely high magnetic fields come out and re-enter at another sunspot, comparable to the field lines in an ordinary magnet from north to south poles. Magenetic fields in the Sun are produced by the fast moving positively charged Hydrogen and Helium nuclei stripped of electrons (known as plasma).
The Sun’s energy if first produced at its center which is at more than 10 million degrees centigrade and at extremely high pressure. Under these conditions, nuclear fusion of Hydrogen and Helium nuclei produces extremely high energy gamma radiation. These gamma-rays take several thousand years to pass through the dense core of the Sun and hence degenerate huge amount of visible light at the surface which is at 6,000 degrees centigrade.
The energy of the fast moving plasma is normally confined within the magnetic field lines that connect from one sunspot to the other. However, when the energy is extremely high, the magnetic field lines break, and cosmic particles are thrown out into space with speeds close to that of light. Such explosions are known as coronal mass ejections or CMEs (see picture).
CMEs are very harmful to humans but fortunately we are protected from these cosmic particles by the Earth’s own magnetic field that forms a protective envelpe. This deflects the harmful particles towards the north and south poles and cause a night glow called aurora. However when CMEs are directly aimed at the Earth they manage to penetrate partly and can harm electronic systems of orbiting spacecrafts as well as on the ground.
The current increase in the number of sunspots after several years of quiet is expected to produce much higher energy CMEs which can be even more harmful to increasing number of communications and research spacecrafts as well as our modern lifestyle which depends on electricity and electronics.
To counter this threat, a new field of space weather is used to understand, monitor and predict the activity of the Sun. Since the Sun rotates about once every 25 days, the sunspots also shift and their numbers and positions change continuously. You can check the status of the sun on the NASA website www.spaceweather.com, which is updated regularly, to know the current status of the Sun.