
Sunspot drawing or sunspot sketching is the act of drawing
sunspots
Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. S ...
. Sunspots are darker spots on the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...
's
photosphere
The photosphere is a star's outer shell from which light is radiated.
The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...
. Their prediction is very important for
radio communication
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...
because they are strongly associated with solar activity, which can seriously damage radio equipment.
History
Sunspots were probably first drawn by an English monk
John of Worcester
John of Worcester (died c. 1140) was an English monk and chronicler who worked at Worcester Priory. He is usually held to be the author of the ''Chronicon ex chronicis''.
''Chronicon ex chronicis''
The ''Chronicon ex chronicis'' is a world wi ...
on 8 December 1128. There are records of observing sunspots from 28 BC, but that is the first known drawing of sunspots, almost 500 years before the telescope. His drawing seems to come around solar maximum. Five days later, the Korean astronomer saw the
northern lights
The Northern Lights most often refers to the aurora borealis.
(The) Northern Light(s) may also refer to:
Arts and entertainment Film
* ''Northern Lights'' (1978 film), about the Nonpartisan League in North Dakota
* ''Northern Lights'' (1997 f ...
above his country, so this is also the first prediction of
coronal mass ejection
A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accep ...
.
In 1612,
Galileo Galilei
Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He w ...
was writing letters on sunspots to
Mark Welser
Mark Welser (1558–1614) was a German banker, politician, and astronomer, who engaged in learned correspondence with European intellectuals of his time. Of particular note is his exchange with Galileo Galilei, regarding sunspots.
Biography
We ...
. They were published in 1613. In his telescope, he saw some darker spots on Sun's surface. It seems like he was observing the Sun and drawing sunspots without any filter, which is very hard. He said, "The spots seen at sunset are observed to change the place from one evening to the next, descending from the part of the sun then uppermost, and the morning spots ascend from the part then below ...". From there it seems that he observed the Sun at sunset, but not at sunrise because of the high horizon of Apennines. It is also possible, that he was referring to
Scheiner Scheiner is a German surname. Notable people with the surname include:
* Artuš Scheiner, Czech painter and illustrator
*Christoph Scheiner, Jesuit priest, physicist and astronomer (born c. 1573)
* David Scheiner (born 1938), American physician and ...
's observation, where he first saw that the Sun is rotating. He complained that he couldn't observe the Sun every morning and evening because of low clouds and so he couldn't see their motion with confidence. He Probably never observed them in the middle of the day. In the same year, his student
Benedetto Castelli
Benedetto Castelli (1578 – 9 April 1643), born Antonio Castelli, was an Italian mathematician. Benedetto was his name in religion on entering the Benedictine Order in 1595.
Life
Born in Brescia, Castelli studied at the University of Padua and ...
invented a new method for observing and drawing sunspots, the projection method. Probably, he was never looking at the Sun directly through the telescope.

The
Mount Wilson observatory
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.
The observ ...
started drawing sunspots by hand in 1917. This tradition continues still today. The early drawers did not draw their shapes and positions very accurately because they wanted just to mark where the sunspots were on the magnetic data. However, in modern times, the drawers became very accurate and sunspot drawing became art; sometimes they needed many hours to complete work. On the white acid-free paper, they draw a circle with solar coordinates and draw and mark sunspots.
Today
With a pinhole and a screen one can produce an image of the Sun. But for better viewings of the sunspots one needs a telescope with 8 inches of diameter or more. There are two ways of drawing sunspots: projection and direct viewing.
Projection on the screen
The easiest way to draw sunspots is to project the image of the Sun to the screen. The further the screen, the bigger the image, but also less bright, so one has to find the perfect proportion. For 10 inch telescope, the optimal distance of the screen from the eyepiece is 1–1.5 meter.
When the Sun is projected, there are two ways for drawing sunspots: you can project Sun on the screen, look at it and draw sunspots on the table, but you can also project the Sun on the drawing paper, just mark the position and draw the shape.
Direct viewing
One less accurate way to do this is to buy the
special filter for blocking the light from the Sun. One can look directly in the telescope in that case and draw the sunspots whilst looking at them.
References
External links
Daily image of the Sun and number of the sunspots
{{the sun
Technical drawing