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Space Science
MOON PROPERTIES AND FORMATION, PROPERTIES OF THE SUN, STELLAR
EVOLUTION
Earth’s Moon

Craters: depressions made from impacts from debris that was left over
during the formation of the solar system.

Rocks on our moon consist of the same elements as Earth’s geosphere,
however not completely similar in amounts of these elements. Lunar
rocks have only small amounts of the same elements as Earth because
many of these elements may have boiled away early in the moons
history.

Many more craters (impacts) from meteorites compared to Earth…why?
The Interior of Earth’s moon

The interior of the moon is less dense than that of Earth.

Weak “moonquakes” read by seismograph readings from the
Apollo mission (more than 10,000 have been detected)

These moonquakes have told scientists much about the
composition of the interior of the moon.

Crust: crust on near side of the moon is thicker than crust on far side
of the moon.

Mantle: made of silica, magnesium and iron. Makes up more than
half of the moon’s interior.

Core: thought to be made out of iron, but not completely solid nor
liquid. This may explain why almost no magnetic field on the moon.
Layers of the Moon
The Formation of Earth’s Moon

Three stages of moon development:

1. The Giant Impact Hypothesis: Large object collided with Earth
more than 4 billion years ago (Mars sized body). Before this impact,
earth was in a molten or very hot, near liquid state. The impact
ejected chunks of the mantle into orbit, which clumped together to
form the moon.

2. The moon was originally covered by an ocean of molten rock.
Over time the more dense materials made their way to the center
to form a small core and the less dense materials formed the crust.

The outer surface eventually cooled to form a thick crust, over
molten material. During this time their were many impacts to form
craters.
Moon Formation
Eclipses: review independent work

https://www.youtube.com/watch?v=PRgua7xceDA

Take Notes!!!
Energy of the Sun
Nuclear fusion occurs inside the sun producing energy.
 The sun’s energy comes from fusion and the mass lost during fusion
becomes energy.


1. two hydrogen protons collide and fuse. A positron is emitted to neutralize
one of the proton’s charge.


One proton and one neutron pair

2. Another proton combines with the proton/neutron pair to create a
nucleus made up of two protons and one neutron.

3. Two nuclei made up of 2 protons and one neutron collide and fuse.
When this happens two neutrons are released. Now 2 proton/2 neutron
Helium atom.
Albert Einstein came up with the equation e=mc2 to describe process
when a small amount of matter makes up a great deal of energy.

Use this equation to find the amount of energy from the sun.
Energy of the Sun
Stellar Evolution

Because stars live for billions of years, it is never possible for
astronomers to be able to observe one star throughout its
development. However, theories have been made studying stars in
different stages.
Star Formation

Stars begin as a nebula. Gravity of the dust particles pull them close
together. As more and more particles build up, more gravitational
attraction is created.

Protostars are created when matter is pulled together to make
compact, dense regions that start to spin.

Once the temperature increases to about 10,000,000 C, nuclear
fusion begins to happen (high pressure and temp). This releases an
enormous amount of energy. A star is born!!!

Force of gravity and outward force from fusion and radiation equal out
to keep star a stable size.
Crab Nebula
Horsehead Nebula
Star formation Cont.

The Main Sequence Stage:


Longest stage in star’s life (current Earth’s sun stage). Fusion creates
energy that is released constantly. Stars similar to the sun stays in this
sequence for about 10 billion years . However, more massive stars only
stay in this sequence for about 10 million years.
Leaving main Sequence Stage

A star enters the third stage when about 20% of the hydrogen within the
core have fused into helium. The core contracts and increases the
temperature of the core. This energy is transferred to hydrogen atoms
around the core, which creates large amounts of outward energy and
great expansion.
Giant Stars and Supergiants

A star’s outer shell starts to cool as it expands and the gases turn red
in color. These stars are called red giants because they are larger
then main sequence stars of the same temperature.

Large main sequence stars will become larger then giants in the
third stage, and will be called supergiants (usually 100 times the size
of our sun).

Betelgeuse is located in the constellation of Orion and is 1,000 times
larger than our sun.
Final Stage of Sunlike Star

Once fusion stops, after the helium atoms have fused into carbon
and oxygen. With no more energy available, the star enters its final
stage

Planetary nebula: As the stars outer gases drift away, the remaining
core heats the expanding gases. These gases appear as a
planetary nebula.

White Dwarf: As the planetary nebula disperses, gravity causes the
remaining matter in the star to collapse inward. This compression
leads to a dense core of material called a white dwarf.

Shine for billions of years before they cool. They are very small and dim
in brightness compared to the novas or supernovas
Final Stage of a Sunlike Star Cont.
Nova and Supernovas: Some white dwarf stars are part of a binary star
system. If a white dwarf is around a red giant, the gravity of the very
dense white dwarf may capture loosely held gases from the red giant.
 As the gases accumulate, the pressure builds up and may lead to an
explosion called a nova.
 A nova may cause a star to be much brighter than it normally is at first,
but then the brightness starts to fade into its normal brightness.



A white dwarf may become a nova many times, as this process can happen
over and over again.
A white dwarf may also become a supernova when there is a
tremendous explosion, which blows itself apart. This is when too much
mass is accumulated from nearby stars. The stars become too dense
that the layers rebound and explode outwards.
Final Stage of Massie Star

Stars that have masses more than 8 times that if our sun may
produce supernovas without needing another star to fuel them.

Massive stars become supernovas as part of their life cycle.

After the supergiant stage, these great stars contract with a
gravitational force much greater than that of small stars.

With the high temperature and pressures, nuclear fusion begins
again, making heaving elements of oxygen and magnesium.
Final Stage of Massive Star

Fusion happens until the core is made up of iron and it starts to
collapse under gravity. Energy released when the core collapses
explode outwards with tremendous force.

Once the explosion in over, massive stars do not become white
dwarfs. Instead they become neutron stars, which is basically an
incredibly dense ball of neutrons.

Neutron stars are very dense and hold a lot of mass: 1tsp from
a neutron star would weigh 2*1030 kg.

Have the same amount of energy as 100,000 suns but only 20
km in diameter
Pulsars and Black Holes

Some neutron stars emit a beam of radio waves that sweeps across
space. Because we detect pulses of radio waves every time a beam
sweeps by earth, these stars are called pulsars.


For each pulse we detect, we know that the star has rotated within that
period.
Some massive stars produce leftovers too massive to become stable
neutron stars. If the remaining core contains more mass than 3 times
our sun, the star may contract further under gravity. The force of
contraction crushes dense core of the star and leaves behind a black
hole. The gravity of a black hole is so great that nothing, even light,
can escape it.

Hard to see (no light) but we can observe black holes by seeing matter from
a companion star being pulled into a black hole. When this happens, X rays
are released and astronomers can locate these rays to find the black holes.
Stellar Evolution
Crab Nebula Pulsar
Galaxies

Galaxies are sprawling space systems composed of dust, gas, and
countless stars.

The number of galaxies cannot be counted—the observable
universe alone may contain 100 billion. Some of these distant
systems are similar to our own Milky Way galaxy, while others are
quite different.

Galaxies with less than a billion stars are considered "small galaxies."
In our own galaxy, the sun is just one of about 100 billion stars.

Most astronomers suggest that galaxies formed shortly after a
cosmic "big bang" that began the universe some 10 billion to 20
billion years ago. In the milliseconds following this explosion, clouds
of gases began to coalesce, collapse, and compress under gravity
to form the building blocks of galaxies.
Galaxies

Largest Galaxies in our Universe

https://www.youtube.com/watch
?v=UE8yHySiJ4A
The Big Bang Theory

Hubble found that a spectra of galaxies, were shifted toward red
shift, meaning that galaxies are moving away form Earth. He
determined the speeds at which these planets were moving, based
on their amount of red shift.

Expanding Universe: The Big Bang Theory suggests that at one point,
billions of years ago, all matter of the universe on compressed into a
very small volume.

About 14 million years ago, a sudden event called the Big Bang, sent all
matter in the universe outward in all directions.

As the universe cooled, some of the matter gathered into clumps,
called galaxies.

Today, the universe continues to expand and galaxies continue to
move apart from one another.
Evidence to Support Big Bang and
Future Research

1965 researchers found comic background radiation, or low levels
of energy spread throughout the universe. Since the Big Bang, the
universe would have cooled to a great extent by now. Energy of
the background energy has a temperature of only 3 C above
absolute zero (-270 C).

Dark Matter: The matter of humans, planets, stars, and the matter
between stars only makes up 4% of the universe. Another 23% is
made up of dark matter, and 73% dark energy.

Dark matter: does not give off light but has gravity that we can detect.

Dark energy: we know almost nothing about dark energy. May be a
force that opposes gravity. May be some dark energy pushing galaxies
farther apart. The rate of expansion seems to be accelerating.