1. Spyros Kitsionas Grade 5 BISS 28/3/2017
The Sun and Stardust
Spyros Kitsionas
Grade 5 BISS
28/3/2017

2. The Sun our nearest Star
We live in a galaxy called the Milkyway because of how it appears on the night sky.
Galaxy = Γαλαξίας (Alex! Help!)

3. The Sun our nearest Star
We live in a galaxy called the Milkyway because of how it appears on the night sky.
The Milkyway contains approx. 100,000,000,000 stars. One of these stars is our Sun!
The Milky way as diameter of 100,000 light years (and thickness of 3,000 light years). The Sun is at approx. 30,000 light years from the centre of our Galaxy.

4. The Sun our nearest Star
Like milk mixing in a cofee/tea mug when stirred with a spoon, the Galaxy (as all as all “Spiral” galaxies) shows a strong spiral pattern on its disc.
Along these spirals, the material of the Galaxy is more condensed. What is the Galaxy made of? Stars and …
… gas and dust!!!

5. The Sun our nearest Star
In fact along the spiral arms gas and dust gets compressed to form clouds. The interaction of these clouds with each other and/or stars in their vicinity makes the gas clouds get really compressed to the degree that they become so hot in their centre that they start shinning like stars!
(The dots show you some of these gas clouds)

6. Formation of stars …

7. … and formation of planets
As the clouds condense to form a star, gaseous material forms a disc around the forming star “waiting” to get slowly funneled to the star.
At the same time material on the disc may start condensing out on its own within the disc forming smaller sized objects.
As the star is now shinning and becoming hot, its heat evaporates the gas that was still on the disc around it. This process reveals the smaller sized objects that formed in the disc which are now the star’s planets!

8. Solar system and planets around other stars

9. Telescopes used

10. What are stars made of?
What material were stars (and planets) made of?
Yeap! Gas and Dust!
It is mostly hydrogen (with a little bit of other stuff … we’ll deal with these later!)
What do stars do with this hydrogen?
Burn it to Helium and heavier elements (carbon, oxygen, nitrogen).
What is the atmoshpere of the Earth mainly made of? That’s right!
Can this be a coincidence?

11. How are other elements made?
Massive stars burn their hydrogen (and helium and carbon-nitrogen-oxygen) very quickly. At the end of their life heavier (metals) are formed such as vanadium, chromium, manganese, iron, cobalt, and nickel etc. Then massive stars (about ten times more massive than the Sun ,or even heavier) burst into what is called a supernova, spreading all of the elements that formed through their lifetime in space. These end up in large distances around what use to be the star. They feed the gas and dust between stars with new elements (remember that we’d talk about these later?) which will eventualy end up in new stars and planets.
What is not thrown up in Supernova stars ends up into a very dense obejct (black hole). Stars like the Sun die to form a neutron star. Small stars form white dwarves.

12. Life on earth? Water? Carbon? In which form around us? Other elements?
Oxygen?
Nitrogen?
What about the Sun in maintaining life?
Photosynthesis?
Chlorophyll?
DNA?
Proteins?
Amin acids? (building blocks of life)
Cell Biology?
Heat?
Habitable zones?

13. Life on earth?
If elements were randomly mixed to form the first proteins this would take much longer than the time it took life to appear on earth (and evolvelt o what is today).
Age of earth 5,000,000,000 years (age of Universe about 15,000,000,000 y)
What could have gone “wrong”?
Amino-acids forming in space and get transformed to Earth on a comet (evidence that they can survive there!) or an asteroid (amino acids have been found on some meaning they formed in space!), survive the friction (heat!) in the atmosphere and get on board our planet!
When? During the early stages of Earth formation.
Do we know of any such huge impacts?
65,000,000 y ago a 10km wide rock hit the earth and what got extinct?
Habitable zones? Other planets? Around other stars?