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A brief history of sunspots.

The Sun

Sunspots are dark areas of irregular shape on the surface of the Sun. Their short-term and long-term cyclical naturehas been established in the past century. Spots are often big enough to be seen with the naked eye. While direct observation ofthe Sun in a clear sky is painful and dangerous, it is feasible when the Sun is close to the horizon or when it is covered by athin veil of clouds or mist. Records of naked-eye sunspot observations in China go back to at least 28 BCE. In the West, therecord is much more problematical. It is possible that the Greek philosopher Anaxagoras observed a spot in 467 BCE, and it appearsthat there are a few scattered mentions in the ancient literature as well. However, in the dominant Aristotelian cosmology, theheavens were thought to be perfect and unchanging. A spot that comes and goes on the Sun would mean that there is change in theheavens. Given this theoretical predisposition, the difficulty of observing the Sun, and the cyclic nature of spots, it is littlewonder that records of sunspots are almost non-existent in Europe before the seventeenth century. A very large spot seen for no lessthan eight days in 807 was simply interpreted as a passage of Mercury in front of the Sun. Other mentions of spots seen on theSun were ignored by the astronomers and philosophers. In 1607 Johannes Kepler wished to observe a predicted transit of Mercury across the Sun's disk, and on theappointed day he projected the Sun's image through a small hole in the roof of his house (a camera obscura    ) and did indeed observe a black spot that he interpreted to beMercury. Had he been able to follow up on his observation the next day, he would still have seen the spot. Since he knew that Mercurytakes only a few hours to cross the Sun's disk during one of its infrequent transits, he would have known that what he observedcould not have been Mercury.

A sunspot

The scientific study of sunspots in the West began after the telescope had been brought into astronomy in1609. Although there is still some controversy about when and by whom sunspots were first observed through the telescope , we can say that Galileo and Thomas Harriot were the first, around the end of 1610; that Johannes and David Fabricius and Christoph Scheiner first observed them in March 1611, and that Johannes Fabricius was the first to publish on them. His book, De Maculis in Sole Observatis ("On the Spots Observed in the Sun") appeared in the autumn of 1611, but it remainedunknown to the other observers for some time.

Harriot's sunspot drawings.

In the meantime, Galileo had shown sunspots to a number of people in Rome during his triumphant visit there in thespring of 1611. But although some of his corespondents began making regular observations a few months later, Galileo himselfdid not undertake a study of sunspots until April 1612. Scheiner began his serious study of spots in October 1611 and his firsttract on the subject, Tres Epistolae de Maculis Solaribus Scriptae ad Marcum Welserum ("Three Letters on Solar Spots written to Marc Welser ") appeared in January 1612 under the pseudonym "Apelles latens post tabulam,"or "Apelles waiting behind the painting."

Legend has it that the famous Greek painter Apelles once hid behind one of his painting to hear what peoplesaid about it. When a shoemaker praised the way Apelles had rendered shoes in the painting, Apelles revealed himself andthanked the shoemaker for the compliment, but this man now proceeded to give his not so complimentary opinions about otheraspects of the painting. Apelles answered "Let the shoemaker stick to his last."
Welser was a scholar and banker in Augsburg, who was a patron of local scholars.

Questions & Answers

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
what is the coefficient of -4×
Mehri Reply
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
I'm 13 and I understand it great
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
I rally confuse this number And equations too I need exactly help
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Commplementary angles
Idrissa Reply
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A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
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Source:  OpenStax, Solar system. OpenStax CNX. Jun 29, 2007 Download for free at http://cnx.org/content/col10432/1.1
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