Suntikan Baru ICT Negara - Akademi Sains Malaysia

fnside the earth
lNslDE ths hot young
Earth, haavy atoms such as
iron were able to sink downwards
lo the cetre, foming a
liouid metalli coro of iron
and nickel, possibly with a
solid core at the cetre. Ths
central tomoerature is
around 4,00O'C.
The lighter atoms, such
as silicon, tloated upward
around th6 outside of lhe
core and formed the mantle.
Above this floats an ever
changing thin crust 10 to 30
km thick.
The Earth's inner core is a solid 2432 km across, probably
lormed mostly from heavy atoms such as iron and uranium.
Around this is a liouid outer core 2270 km thick made of iron and
lighter aloms such as orygen and sulfur.
Around lhe core is lhg mantle.
The Earth's magnetic field is lhoughto originate in the core.
The core is believed to be kepl warm by radioactive decay.
Rocky Snowballs
As the Earth formed out of
roclq snowballs it glow hot and
probably melted. One theory is
that early in its history a large
obtecr hit the Earth, which threw
out a shower of rocks. These
collected logether to torm lhe
Moon. ll il is true this would certainly
havs made the Earlh melt.
The grazing impact ol a Marssized
body with the proto-earth
more than lour billion years ago
is believed to have lsd to the tormation
of our moon.
About 300 thousand ygars atl€r
ths Big Bang, the Universe had
cooled lo be captured by protons
and alpha particlss lo iorm atoms.
An elsctron is pull€d towards a
proton because their oppositg 9l6ctric
cfiarges attract each olher.
They stick tog€thsr to form a totally
n€w kind of object callod an atom
ol hydrogen. In the same way two
slectrons were altracrtad to each alpha particle, whlch contained
two protons, and wer€ hsld doss to it. The alom lhey mad€ is
called a h€lium atom.
Atoms are tantastic things. Around the oulsids ol the atom the
€lectron forms a lafgo, thin sh6ll. Insid€ ths alom is smpty space,
except for the tiny heavy proton at ths csntre. An atom is like a
lootball.
The electron in an atoms is like tha skin of lh€ foolball. Undor
this skin the atom is almost smpty. At lhs c€ntre is somothing a
football doesn't have. Hsld at the center by lho olectric lorc€ is
the tiny proton. This is called the nusleus of the atom- Ths young
Universe was tull of hol atoms, moving around and bouncing off
each olhs( They made a gas.
Onc€ all lhe el€ctrons were atoms trapped in aloms, the fog ot
the Universo cieared.
zzesti}otmq
o
The Crust
The crust of th6 Earth is a thin dgid layer
of rock. lt ffoats on lhg mantle.
It is made mostly of a layer of dark rock
called basalt and is 5-10 km thick. The
oceans lie above this layer. Trapped in this
basalt are lumps ol thicksr rocks similar to
granite, 30 - 40 km thick. These lumps stick
orjt of the oceans to form lhe @ntinents.
Oceanlc crust