Download Astronomy PowerPoint - Petal School District

Astronomy
Universe: all of space and
everything in it
Most (90%) of the universe is made up of:
dark matter: stuff we think is there due to
amount of mass we think is there but is
not detected by the instruments we
have available at this time
http://media.skysurvey.org/interactive360/index.html
Nebula: large amount of gases
spread out in an immense volume
• All stars start as part of a nebula
Star: large amount of glowing gas in
a small volume
•
mostly hydrogen
It creates energy through nuclear
fusion of hydrogen to helium in its
core.
We see and feel this release of energy
as “sunshine”
Globular cluster: a group of 10,000
to 1 million stars (that’s a LOT)
Galaxy: a giant structure that
contains hundreds of BILLIONS
of stars
3 main types:
1.
spiral
2.
elliptical
3.
irregular
1.
spiral: have arms that spiral
outward like a pinwheel
Milky Way: our galaxy
We are on an outer “arm”.
2. elliptical: looks like a flattened ball;
3. irregular:
No regular shape
Galactic cluster: groups of
galaxies held together by
gravity
The Milky Way is part of a galactic cluster with 30
other galaxies traveling together called,
“The Local Group.”
Life Cycles of Stars
Supernova: explosions of dying
large stars. Can be seen without
a telescope.
Neutron star: extremely small,
dense leftovers from a supernova
supernovae shrink into neutron stars
Black hole: what remains after the
most massive stars die
• gravity is so strong that nothing can
escape (not even light)
• many scientists think the center of
Milky Way contains a black hole
Artist’s
rendition.
Not a real
photograph!!
How we get information about space:
(no man has ever been farther than the moon)
One way: space telescopes!
the Hubble Space Telescope
(looks at distant galaxies & at planets in our solar system)
Kepler Space Telescope
(looks for planets around other stars (exoplanets))
How do we measure movement and
distances
in
space
Within our solar system we use radar
and the formula for speed:
Speed = distance/time
Speed of light = 186,000 mi./sec or
300,000km/sec.
That’s around Earth 7 ½ times in one
second!
ALL EM waves travel at the speed of
light.
Measuring Distance within our Solar
System.
Astronomical Unit (AU):
distance between the Earth and Sun
•Approximately 93,000,000 miles
•Used only within our solar system to
measure distances between planets
and the sun
Measuring Distance outside our Solar
System.
Light-year: distance light travels in
one year at the speed of light.
If Speed of light = 186,000 mi./sec, then a
Light-year = 5.9 trillion miles
(5,900,000,000,000 miles)
•Takes about 8 minutes for sunlight to reach
Earth
Takes about 4 years for starlight from next
nearest star to reach Earth.That star is 4 light-years
away! Alpha Centauri
Parallax: the apparent change
in position of an object when you
look at it from different places
•used to measure distance to
nearby stars
•smaller shift = greater distance.
Doppler effect
Red shift - longer
wavelenghts : moving
away from you.
Blue shift- shorter
wavelengths: moving
toward you.
Red -away ; blue toward you.
Doppler effect
Red shift
Blue shift
Telescopes collect and focus
different types of
electromagnetic radiation,
including visible light.
Optical telescopes are
used to see distant or
faint objects by
magnifying the amount
of light they emit.
O
Hubble Telescope
Radio Telescopes
• collect radio waves from space to
convert to images so we can “see” the
source.
• easily detects waves through our
atmosphere.
Robert C. Byrd Green Bank Telescope (GBT)
Infrared Telescopes
• Can be on the ground or above
atmosphere.
• Used to measure temperature of
celestial objects, their composition
and to locate planets around other
stars. Exoplanets
Infrared telescopes on
Mauna Lea in Hawaii
I
Robert C. Byrd Green Bank Telescope (GBT)
Ultraviolet Telescopes
• Placed outside Earth’s atmosphere.
• Detect hot, young stars in other
galaxies
Galex UV Telescope
Robert C. Byrd Green Bank Telescope (GBT)
X-Ray Telescopes
• Are placed outside Earth’s
atmosphere.
• Observe supernova remnants, X-ray
pulsars, black holes, neutron stars, and
hot galactic clusters.
Chandra X-ray
Telescope
Robert C. Byrd Green Bank Telescope (GBT)
Gamma Ray Telescopes
• Are placed outside Earth’s
atmosphere.
• Gamma rays often come from objects
like black holes and exploding stars
Fermi Gamma Ray
Telescope
Robert C. Byrd Green Bank Telescope (GBT)