Transcript Galaxies and the Universe - Grandview Independent School

The Universe
Cosmology
• the branch of astronomy that
deals with the origin, large-scale
properties, and the evolution of
the observable universe
The Universe
• in astronomy, the sum total of all things
which can be directly observed or whose
physical effects on other things can be
detected
• in simpler terms, space and all the matter
and energy in it
Can you think of something in
• major components:
the universe that cannot be
– galaxies
– solar systems
– planets
seen, but its effects on other
things can be detected?
“Big Bang” Theory
• the primeval explosion of space, time, matter and
energy that most astronomers think gave rise to the
universe as we see it today.
• occurred about 13.7 billion years ago
• thought to have expanded from something smaller
than the size of a spec of dust
Misconception Alert:
Describing this theory as
the “Big Bang” is a misnomer
because there really was not
an explosion, just a release of
energy
Edwin Hubble
• determined that other
galaxies exist, besides
the Milky Way
• observed that galaxies
were moving away from
each other
– Hubble Law – the farther
away a galaxy is, the
faster it is moving away
from us; supports the Big
Bang Theory
Image taken from:
http://apod.nasa.gov/apod/ap960217.html
Galaxy
• a large assemblage of stars (and often gas and dust),
typically containing millions to hundreds of billions of
member stars
– Star - a large hot ball of gas which generates energy in its core by
nuclear reactions
• around 100 billion in the universe
• held together by the gravitational attraction of all its
member stars on one another
• formed around 200 million years after the “Big Bang”
• most large ones seem to have super-massive black holes at
their centers
• sometimes contain very bright centers called quasars
• 3 major types:
– Spiral
– Elliptical
– Irregular
What is the name
of the galaxy
we reside in?
3 Types of Galaxies
Spiral
have arms of stars, gas ,
and dust that curve away
from the center of the
galaxy in a spiral pattern
Ex. – Milky Way
Elliptical
shaped like
spheres or eggs;
have almost no
dust or gas
between stars;
contain old stars
Irregular
faint galaxies without
a definite shape;
smaller than the other
types of galaxies;
contain fewer stars
The process of galaxies colliding to create a larger galaxy is known
as “galactic cannibalism.”
Images taken from: http://school.discoveryeducation.com/schooladventures/universe/galaxytour/toknow.html
Milky Way Galaxy
• Scientists now know that black
holes are inexorably linked with
galaxies, lying at their center and
directly influencing how large a
galaxy may grow. These aren’t
your ordinary stellar variety black
holes of mass couple of times that
of our sun. No, these are classed
as supermassive black holes and
can have millions or, in some
extreme cases, billion solar
masses. Our own galaxy, the Milky
Way is no exception.
Constellation
• a group of stars that form a pattern in the sky
• stars of a constellation are often far apart from each
other, but they appear grouped together when viewed
from Earth
• one of 88 sectors into which astronomers divide the
sphere of the sky – named after a traditional constellation
in that sector
• patterns of constellations are dynamic; therefore, the
constellations of 100,000 years ago are quite different
from today’s
• a part of a constellation that forms its own pattern in the
sky is known as an asterism (ex. – The Big Dipper)
Why is it not possible to see all constellations at once?
Solar System
• the sun and all things orbiting around it,
including the eight major planets, their
satellites, and all the smaller pieces such as
asteroids and comets
• formed around 4.6 billion years ago
What is
incorrect
or misleading
about this
visual?
Image taken from:
http://asm.arc.nasa.gov/Gallery/images/generic/LG_Capableofeverything.jpg
Planet
• derived from a Greek word
that means “wanderer”
• a major object which orbits
around a star
• in our solar system, there are
eight such objects which are
traditionally called “planets”
Asteroids
Image taken from:
http://www.windows.ucar.edu/tour/link=/our_solar_system/asteroids.html
• small, solid, rocky
bodies that orbit close
to the Sun
• most found between
the orbits of Mars and
Jupiter in the
“Asteroid Belt”
• thought to be leftover
material from the
formation of the solar
system
• range in size from
1000 km or 621 miles
(Ceres) to the size of
pebbles
Meteoroid, Meteor, Meteorite
• Meteoroid – solid debris from space
(asteroids) that are moving
towards Earth
• Meteor
Meteoroid (asteroid)
Meteor
Meteorite
– a brief streak of light produced by
a small particle entering Earth’s
atmosphere at high speed
– often referred to as “shooting
stars” or “falling stars”
– travel at speeds between 11-72
kilometers per second (6.8 – 44.7
miles per second)
• Meteorite – a small object from
outer space that passes through
Earth’s atmosphere and reaches
the surface
• Freehold Meteorite - MSNBC
• Freehold Meteorite - USA-Today
What causes a meteor
shower to occur?
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
Comet
Image taken from:
http://www.space.com/bestimg/index.php?guid=45b0fd31f065d&cat=bestcomet
• a small body of ice and
dust (“dirty snowball”)
that orbits the Sun
• contain a head (coma)
followed by a tail(s) of
gas and dust
• the tail always points
away from the sun and
can be millions of
kilometers long (but the
amount of matter it
contains can be very
small)
Satellite
• an object that orbits a more massive
object (i.e. – moons)
• probes we launch into orbit around the
Earth are called “artificial satellites”
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
Telescope
• a device that gathers electromagnetic radiation
• Types:
– Visible, infrared, ultraviolet – pick up visible,
infrared, and ultraviolet waves
• Reflecting - use mirrors that reflect the image being
viewed
• Refracting – using lenses, gathers light and focuses it
near the opposite end of the tube; works like a magnifying
glass
– Radio - pick up radio waves emitted from space;
not effected by variables like weather or clouds
Internet Telescope
Hubble Space Telescope
• a reflecting
telescope that was
placed into orbit in
1990
• sends images and
measurements back
to Earth
electronically
Image taken from:
http://hubblesite.org/gallery/
What is one of the main
benefits of having the Hubble Space
Telescope in orbit, as opposed to
it being here on Earth?
Edwin Hubble at Mt. Wilson
Hubble’s observations at the 100 inch during the
1920’s led him to the conclusion that the universe
is expanding, and that an object’s recession velocity
is proportional to its distance from the observer.
Hubble guiding the Hooker
100 inch telescope in 1923.
The Hooker 100 inch telescope atop Mt. Wilson
near Pasadena, CA. It was the largest telescope in
the world from 1917-1947.
Hubble’s
namesake
The Hubble Space Telescope's launch in 1990 sped
humanity to one of its greatest advances in that journey.
Hubble is a telescope that orbits Earth. Its position
above the atmosphere, which distorts and blocks the
light that reaches our planet, gives it a view of the
universe that typically far surpasses that of groundbased telescopes.
Hubble is one of NASA's most successful and longlasting science missions. It has beamed hundreds of
thousands of images back to Earth, shedding light on
many of the great mysteries of astronomy. Its gaze has
helped determine the age of the universe, and the
identity of quasars
Hubble facts
The Hubble Telescope is
roughly the size of a school
bus, but still fits into the cargo
bay of a space shuttle
Mission
Launch: April 24, 1990 from space shuttle
Discovery (STS-31)
Deployment: April 25, 1990
Mission Duration: Up to 20 years
Size
Length: 43.5 ft (13.2 m)
Weight: 24,500 lb (11,110 kg)
Maximum Diameter: 14 ft (4.2 m)
Cost at Launch: $1.5 billion
• Spaceflight Statistics
Orbit: At an altitude of 307 nautical miles (569 km, or 353
miles), inclined 28.5 degrees to the equator (low-Earth orbit)
Time to Complete One Orbit: 97 minutes
Speed: 17,500 mph (28,000 kph)
Deep Hubble Space Telescope Image
A deep image of an “empty”
portion of the sky with the
Hubble Space Telescope
reveals that the universe is
filled with galaxies- many just
like our own. The light
we see from the most distant
galaxies has traveled approximately 10 billion years to
reach us.
Deep Hubble Space Telescope Images
http://hubblesite.org/videos/
http://tools.wmflabs.org/zoomviewer/index.
php?f=Earth%27s_Location_in_the_Univer
se_%28JPEG%29.jpg
Astronomical Unit (AU)
• unit of distance equal to the average spacing
between the Earth and the Sun
• equal to about 150 million kilometers (93
million miles)
• light takes about eight minutes to cover this
distance
150 million km
(93 million mi.)
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
Light Year
• the distance that light travels in one year in a
vacuum, which is about 9.5 trillion kilometers
(6 trillion miles)
– The Milky Way Galaxy is about 100,000 light years
in diameter
• the speed at which light travels this distance
is about 300,000 km/sec (186,000 mi/sec)
The second closest star to the Earth is a
little over four light years away. How far
away (in miles) is the star?
Parsec
• unit of distance equal to about 3.26
light years (or 206,265 AU)
If one parsec equals 206, 265 AU, how
many miles is it equal to?
Parallax
• the apparent shift in position of an
object when viewed from different
locations
• used by astronomers to measure
distance
Put your pointer finger in front of your face and begin
opening and closing your eyes in an alternating manner. What
do you notice about the your finger’s position?
Parallax Simulation
Parallax Simulation – 1
Parallax Simulation - 2
Find the Distance to HT Cas Using Parallax