Earth and Space
Spotting sunspots
Stories from Physics
for 11-14
14-16
- There is evidence of observation of sunspots in ancient Greek and Chinese astronomical records. One of the earliest telescopic observations of the phenomenon was made by amateur father-and-son observers David and Johannes Fabricius in 1610. On David’s birthday, the pair noted dark spots on an image of the Sun projected through a telescope. Johannes published an essay on his discovery, preceding Galileo’s description of sunspots by a year. The pair did not survive to see the impact of their discovery - Johannes died four years later and his father was murdered shortly after by a farmer whom Fabricius had accused of stealing a goose.
- Whilst to the Earth-based observer, sunspots look like small black spots on the surface of the Sun, their appearance is deceptive as they are perceived in relation to the Sun. Sunspots can have a diameter of up to 100,000 km and have temperatures of around 4,300 K. Seen in isolation, a sunspot would be around a hundred times as bright as the full Moon and only seem dim in comparison to the surrounding surface of the Sun.
- The Sun’s magnetic field can reverse at times of maximum sunspot activity. In 2001, the solar magnetic field suffered such a change and the reversals are hypothesised to follow the 11-year cycle of sunspot activity.
References
Spotting sunspots
R. E Benestad, Solar Activity and Earth’s Climate, Chichester, Praxis Publishing Inc., 2003, p. 38
G. Schilling, Atlas of Astronomical Discoveries, New York, NY Springer, 2011, pp. 15-16
C. R. Kitchin, Stars, Nebulae and the Interstellar Medium: Observational Physics and Astrophysics, New York, NY, Taylor and Francis Group LLC, 1987, p.185
