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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

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
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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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