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Natural sciences

Grade 9

The earth, galaxies ans space programmes

Module 14

The sun

For us the earth is the centre of our existence and for many years people believed that the earth was also physically the centre of everything. It was Copernicus (1473-1543) who moved away from this geocentric view and formulated his heliocentric theory. This caused a sensation and forced science in another direction. Johannes Kepler (1571-1630) expanded on this theory and maintained that planets in our solar system revolved in orbits around the sun. He formulated three laws of planetary movement that scientists use today.

The Sun – Our Star

  • The sun is a spinning ball of fire (burning hydrogen and helium gasses). Its volume is 1.3 million times that of the earth and it weighs 333 420 times more.
  • The pressure in its core is extremely high and converts the sun into a giant nuclear power plant. It splits hydrogen atoms and in this way creates temperatures of up to 15 million o C. This causes the surface of the sun (photosphere) to be turned into an inferno that glows at about 5 500 o C.
  • The sun has spots that shoot out solar flames of up to approximately 100 000 km. These solar flames can disturb radio waves and therefore interferes with broadcasts.
  • We call the atmosphere of the sun the chromosphere. It is surrounded by the corona.
  • The SOHO (Solar and Heliospheric Observatory) was launched by NASA in 1995 and now orbits the sun to transmit information about the sun to the earth.

solar eclipses

  • SOLAR ECLIPSES occur when the moon comes between the earth and the sun. The eclipse is often only partial and then it is like dusk, as it was on 21 June 2001. During a total eclipse of the sun it becomes completely dark. Such an eclipse occurred in the northern part of our country on 4 December 2002, when it became completely dark.
  • Any given town or place on earth will experience about 40 lunar eclipses and 20 partial solar eclipses in any 50-year period. A total eclipse of the sun such as the one in December 2002 occurs only once every 400 years in a particular place.
  • The next total solar eclipse in South Africa will only occur in November 2030.
  • The dark part of the eclipse is called the umbra ( U ) – or area of total shadow.
  • The outer parts are only partly shaded and are called the penumbra (P).
  • A total eclipse lasts 7,5 minutes, as the earth rotates and the observer moves out of shadow.
  • Only people in the path of the shadow of the eclipse will be able to observe the eclipse.
  • When observing a solar eclipse one has to protect ones eyes. Permanent damage to eyes can be caused if the right precautions are not taken.
  • Special spectacles can be made or bought. A simple method is to take a piece of cardboard that will fit over your eyes and cut out a small ‘window’. The window should be covered with a double layer of the foil in which teabags are packaged.

Research assignment 2:

Visit the following websites to learn more about solar eclipses:

Also find out more about various beliefs regarding solar eclipses in ancient times.

What did the Chinese believe? And the Tahitians?

Pythagoras, the Greek, was the first to explain eclipses. Why do you think this was?

Assessment of Research Assignment:

Did you a) plan how you would obtain the information, b) collect information and

c) communicate information and findings?

[LO 1.1; LO 1.2; LO 1.3]


LO 1: Scientific investigations:

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

This is evident when the learner:

  • plans investigations;
  • conducts investigations and collects data;
  • evaluates data and communicates findings.



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.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Natural sciences grade 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
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