The document discusses the origin and evolution of the universe from the Big Bang to the present day. It describes how the universe began in a hot, dense state and has been expanding and cooling ever since. As it expanded, the first atomic nuclei formed via nuclear fusion. Over time, these atoms gathered together through gravity to form structures like galaxies, stars, and planets. The document also examines different astronomical objects like nebulae, quasars, and black holes that can be observed in the universe.

2.  El universo tuvo su origen en la gran explosión.
 La gravedad hace que las galaxias se atraigan unas a otras,
y por tanto impide que el universo se expanda ,
 Si la densidad del universo no es suficiente para que la
gravedad frene la expansión, entonces el universo se
expandirá para siempre de lo contrario si la densidad es
grande, la fuerza de gravedad será muy intensa y podría
llegar a frenar la expansión, Si la densidad es la justa para
que la expansión se frene en un tiempo infinito, a esta
densidad se le llamara densidad crítica .
 Formas de medir la densidad del universo: medir la cantidad
de materia brillante otra forma es midiendo la masa
dinámica

3.  La masa determinada de forma dinámica es mucho mas
grande que la obtenida observando la materia brillante. Hay
una gran cantidad de materia que sabemos que existe
porque detectamos sus efectos gravitatorios.

4.  La forma de estudiar el universo consiste en medir la
variación de la velocidad de expansión, como empezó a
hacer Hubble( descubrió la galaxia de Andromeda) .
Recordemos que si miramos muy lejos el universo estamos
mirando hacia el pasado, debido a que la velocidad de la
luz es infinita.
 En el pasado la expansión era más lenta que en la
actualidad, el universo se está acelerando. Dado que la
fuerza de la gravedad hace que las galaxias se atraigan
unas a otras, si el universo esta acelerando debe de existir
una fuerza desconocida de tipo repulsivo.
 Desconocemos completamente el 70% del contenido del
universo y desconocemos la fuerza más importante de
cuantas actúan en el universo

5.  The universe is the sum of all that exists, this includes the time,
the space, the matter, the energy, etc…
 The geocentric model .Aristotle established that the earth is
motionless and that it is located in the center of the universe.
All revolved in perfect circles around the earth. Ptolemy
called this model the geocentric model.
 The heliocentric model. Copernicus proposed the sun is
motionless, it is located in the center of the universe and all
revolve around it.
 The Big Bang theory. Hubble discovered that the galaxies
move away from each other at speeds proportional to
theird distance ( Hubble´s Law)

6.  What happened after the Big Bang?
The universe was very hot, it was formed by a plasma of
protons and electrons particles. Nuclear reactions were
produced and atomic nuclei ( its consisted of several
protons and neutrons, such as helium, lithium, etc) were
formed. This is called primary nucleosynthesis. The
nucleosynthesis ended when the universe was cooling down.
The proportion of universe gases was similar to the current
proportion: 25% helium and 74% hidrogen atoms. The
expansion continued and the atoms were grouped and they
formed higher density structures. These estructures are the
galaxy which contain stars and planets.

7.  Galaxies are huge groups of stars, gas and dust. They differ
by their different shapes and sizes, and the number of stars
that they contain. There are diferent types:
- Spiral galaxies. Contain a central area or core and a
variable number of arms.(milky way)
- Elliptical galaxies. They haven’t arms. They consist of old
stars and are the largest galaxies know.
-Irregular galaxies. They haven’t definite form and they are
most abundant. Some of them, given their size, are classified
as dwarf galaxies.

8. Nebulae
 Are giant clouds of gas and dust with different shapes. The
nebulae and the supernebulae are the result of big exploins that
occur at the end of the life of very massive stars.
Quars
Are stellar objects that emit a large amount of energy as radio
waves.
Black Holes
Are objects in which the light can’t escape because of their
enormous gravitational attraction.

9.  Los sistemas planetarios están formados por grupos de
planetas, satélites y otro objetos (cometas y asteroides) que
orbitan alrededor de una estrella. Las estrellas súper gigantes
rojas pueden explotar al final de su vida y expulsan gas y
polvo que contienen hidrogeno, helio y otro elementos. Esta
materia es la base para formar nuevas estrellas, pero una
pequeña parte podría permanecer alrededor de la estrella y
ocasionar la formación de planetas.

10.  Nuestro sistema solar consta de ocho planetas:
- Cuatro planetas interiores o rocosos son las mas próximos al
sol (mercurio, Venus, La tierra y Marte) con nucleos metalicos
y una corteza de aspecto rocoso.
- Cuatro planetas exteriores (saturno, jupiter, urano, neptuno)
con un nucleo metalico pero compuestos sobre todo de
hidrogeno y helio.

11.  Satelites: Astros que orbitan alrededor de los planetas
 Asteroides: objetos de menor tamaño que los planetas y
satelites que destacan el cinturon de asteroides entre Marte
y Hupiter.
 Cometas: objetos con un nucleo solido formado por agua
y amoniaco, cuando se acercan al sol desprenden
particulas que forman la cola del cometa.
 Meteoritos: fragmentos de planetas, cometas y
asteroides que van a la deriva con el espacio. Pueden caer
sobre la superficie de los planetas y su tamaño varia.

12.  The stars are formed in a nebulae, they get oold and die
when they have run out of combustible after thousand of
million of years.
 Energy of a stars The stages in the life of a star dependet
on the amount of energy that is capable of generating at all
times.
 Nuclear fusion is a reaction in which two simple atoms come
tougheter and combine their nuclei to form a new atoms
much more complex.
 In the stars the union of two atoms of hidrogen is produced
to form helium providing a lot of energy.

13.  Vital cycle of a star. Starts are born in galactic nebulae
wich are composed manly of hidrogem and helium this
clouds of gas and dust are abundant in young galaxies like
ours. In our galaxy there are many examples of great
nebulae where star are being born.
 Protostar. The contraction of the nebulae dued to the
gravitiational attraction produce the formation of thousand
of stellar-mass fractments called protostar (they are formed
by hidrogen)
 Young star. Gradually the hidrogen will become into
helium through nuclear fusion. Then the protostar will
become a star.

14.  In the supergigant start that the nuclear
fusion of helium is going to produce
elements like carbon and oxygen, Now the
start has two areas of energy production:
the core where the helium is converted into
oxygen and carbon and the outer layer
where the hydrogen is converted into
helium and in the size.