Sunspots are spots of cooler temperatures on the sun. They appear darker than the rest of the sun and occur in a region called the photosphere. The photosphere has a temperature of 5,778 kelvin compared to sunspots that have an average temperature of 3,500 kelvin.
Sometimes there are hundreds of sunspots on the sun. The sunspots come and go, with huge fluctuations between times of maximum and minimum sunspot activity, the overall cycle being around 11 years in length. Sunspots usually occur in small groups in several different places all over the sun.
Sunspots were first recorded as having been seen as far back as 28 BC. However, Galileo was the first person to investigate and record the behavior of sunspots.
Sunspots are not fully understood but are generally believed to be caused by a change in the sun's magnetic field through the process of magnetic re-connection. Magnetic re-connection is where magnetic field lines are broken and reconnected causing inflowing magnetic energy to convert to kinetic energy. Sunspots occur in regions of intense magnetic energy, usually 1000 times the magnetic field strength of their surroundings, and are around 37,000 kilometers in diameter on average, making them much larger than planet Earth. When the energy is released it causes solar flares and coronal mass ejections (a coronal mass ejection is an eruption of magnetic plasma) to erupt from the sunspots.
How do Sunspots affect the Earth?
The sun is the sole source that allows life to thrive on Earth. This is because it is the key driver of photosynthesis in plants. Without the sun there would be no life on Earth at all. Sunspots were thought to affect plants because of the light needed for photosynthesis. During high sunspot activity less energy would be coming from the sun because of the lower temperatures. However, this is not now thought to be the case.
Sunspots have been linked to interference with magnetic instruments on Earth; increased activity of sunspots causes there to be more interference with magnetic instruments.
Solar flares from the sunspots cause increased x-ray energy to be projected at the Earth in the form of a geomagnetic storm. These geomagnetic storms cause interference on Earth and can even stop electrical equipment from working.
How do Sunspots affect the Earth's Climate?
There is an increase in ultraviolet rays produced from sunspots. The increase of ultraviolet rays from sunspots affects the outer atmosphere of the Earth. Ultraviolet rays also can cause skin cancer and skin related illnesses.
The effect of sunspots on the climate of planet Earth is thought to be very small. According to a study on the effects of low sunspot activity conducted by the Potsdam Institute for Climate Impact Research, if there was a sudden reduction of sunspots now it is estimated that in the year 2100 the temperature would be reduced by 0.26 degrees Celsius. Human impact on the climate suggests that there would be an increase in average temperature of the Earth from 3.5 degrees Celsius to 4.5 degrees Celsius in the year 2100.
It is still debated whether sunspots really affect planet Earth.