Grade 8 Natural Sciences (NS) Summaries - Term 4 (Via Afrika): These summaries are compiled using the Via Afrika textbook's Term 4 content. The summaries are in English, with additional notes provided by the compiler.
Strand 4 - Planet Earth and beyond
Topic 1: The Solar System
Topic 2: ...
, Light years, light hours • A system of stars held together by gravity. The Milky Way Galaxy
• Comprises the Sun and over 100 billion other stars.
and light minutes • The Milky Way band encircles the entire sky, resembling luminous clouds.
• Milky Way's hazy light path was caused by milk spilt during Hercules' feeding by Juno.
• Distances to stars and other objects
• Galaxy's shape formed by the positions of billions of stars.
beyond the Solar System are too large
• Spiral shape with curved arms from another galaxy.
to be measured in kilometres.
• Sun and Earth in one of the spiral arms.
• Measurements are expressed in terms
• Brightness varies depending on viewing direction.
of light travels in a year, a day, or an
• Galaxy rotates around its centre, with stars near the centre moving the fastest.
hour.
• Light travels 300,000 km in one
second, approximately seven and a Our nearest star
half times around Earth.
• Light Years: • Alpha Centauri - Brightest star in Centaurus, 270
Sample
o A light year is the distance light
travels in a year, approximately 10
trillion kilometres.
o Alpha and Beta Centauri are
approximately 4.2 light years away,
T2: Beyond
the Solar
System
thousand times further from Earth than Sun.
• Brighter of two Southern Cross pointers.
• Second light bulb 80 km away from first.
• Despite proximity, distant from Solar System.
42 trillion kilometres away, and 300
Summaries after sample
The long wait for signals
light years away respectively.
• Light Hours: from Alpha Centauri
o Light travels in an hour, with Sun-
Neptune distance being 4 light hours. • Radio signals travel at
o Sun's light travels 6 hours beyond Beyond the Milky Way Galaxy light speed, a million
Pluto to the Kuiper belt. times faster than
o The Solar System's diameter is • Beyond the Milky Way Galaxy: sound.
approximately 13 light hours. o One of billions of galaxies with ideal conditions for observing 2000-2,500 stars. • Alpha Centauri's
• Light Minutes: o One of billions of other galaxies with a vast number of stars. signals took 4.2 years
o Sun's light travels 8 minutes to Earth. • Size of the Observable Universe: to reach Earth.
• Looking Back in Time: o Big Bang Theory suggests the Universe was once hot, tightly packed matter • Beta Centauri's
o The Sun's sudden 'switching off' could expanding rapidly. signals took 300
be detected in 8 minutes. o The Universe's age is approximately 14 billion years, making it difficult to see years.
o Southern Cross pointers show Alpha galaxies further than 14 billion light years away.
Centauri and Beta Centauri as they • Shapes and Sizes of Galaxies:
were 4.2 and 300 years ago. o Three neighbouring galaxies visible from Earth: Great and Small Magellanic Clouds,
and Andromeda Galaxy.
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller SummariesSA. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R100,00. You're not tied to anything after your purchase.
