Download Diapositiva 1

Annapaola & Francesca Donateo
present
ASTRONOMY
What’s astronomy?
It’s the branch of geography which
helps us to get acquainted with the
sky. It is also the study of the sun, the
moon, the planets and other
astronomical bodies. It includes
learning about the Earth, because the
Earth, too, is a planet.
What are
stars?
When we observe the sky on
a clear, dark night, the first thing that
we note are the stars, seen as little pinpoints of light.
But …
Stars
Stars are astronomical body of
gaseous composition, animated by
nuclear reactions, able to give out
energy in the form of
electromagnetic radiations. They are
made of helium and hydrogen.
Often stars appear grouped in pictures
that we called constellations. However
stars aren’t at the same distance … it’s
only an illusion of the observer. The
most important constellations are …
Orion
Orion is a
constellation formed
by 130 stars and the
alignment of three
of them form the
so-called Orion’s
belt.
Ursa Maior
and Ursa Minor
Ursa Major is a constellation of typical boreal skies, its seven
brightest stars, grouped in the famous Big Dipper asterism, are
visible throughout the year in the northern hemisphere.
Ursa Minor is a constellation of the northern sky. It is especially
known because within it lies the north celestial pole, although its
position is subject to a continuous, slow movement due to the
precession of the Earth's rotation. The Little Dipper is easily
identifiable because, once detected the Big Dipper, you can reach the
Pole Star, the brightest star in Ursa Minor
Cassiopeia
Cassiopeia is a northern
constellation,
representing
Cassiopeia, the
legendary queen of
Ethiopia. The
constellation is easily
recognized by its shape
W or M.
Observing the sky, it seem that
everything revolve around the
Earth, that appeared to be the
motionless of the universe. But
today we know that only the moon
revolves around the planet. The
Earth itself travels around the Sun
with other seven planets in the
Solar System.
The Sun is the centre of the Solar System, around which
everything revolves. It is also the only
source of energy, the same
that terrestrial organisms
exploit to perform their
normal activities.
The Sun is one of numerous stars
that form our galaxy, called the Milky Way.
Milky way
It’s an enormous discus of stars (100
milliards) long about 100 000 lightyears and thick 10 000 light-years.
It’s characterized by a central
swelling , called galactic nucleus,
from which depart arms, where the
density of the stars is higher.
The solar
system
The solar system is the planetary
system formed by a variety of
celestial bodies kept in orbit by the
force of gravity of the Sun, the Earth
also belongs to it. Is composed of
eight planets, by their natural
satellites, five dwarf planets and
billions of small bodies. The planets
that compose it are …
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
The end
Thanks for your attention.