Download The Sun and Stardust

The Sun and Stardust
Spyros Kitsionas
Grade 5 BISS
28/3/2017
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!)
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.
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!!!
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)
Formation of stars …
… 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!
Solar system and planets around other
stars
Telescopes used
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?
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.
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?
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?