Transcript The Universe: Galaxies, Stars, and Nebulae

Light Year
This
is a DISTANCE not an amount of
TIME
EX: 3 Miles is a distance, 3 Years is a
time
Used to represent extremely LARGE
distance in space
Remember, Light is a Transverse Wave –
and all waves travel, they don’t just appear
So how far is it?
distance is very large – it’s hard
for the mind to understand how far
this is
 Speed of Light = 300,000 km/sec
 That’s about 18,000,000 km/min
 This
So how far is it?
 Speed
of light is about 186,000
miles/sec
 That
is about 671,000,000,000,000
miles per hour (671 Trillion mph)
So how far is it?
 Now
that you know how fast light
travels it time think about distance
 If we look at how far light would travel
for ONE full year – that distance is a
Light Year!
One Full Year
 The
total distance light travels in one
full year is about: 9,460,000,000,000
km (9.46 trillion km)
 In terms of miles that is about:
5,800,000,000,000 miles (5.80 trillion
miles)
An example close to home…
 So
how far is that distance of a light
year… really.
 EX: it is about 370,000 km from the Earth
to the Moon. If you could walk from the
Earth to the Moon, how many times would
you have to go that distance to equal a
light year?
 ANSWER: about 12 MILLION times back
and forth from the Earth to the Moon!
The Universe: Galaxies,
Stars, and Nebulae
March 3, 2011
The Universe
 All
physical matter and energy that
exist in space:
 Planets
 Stars
 Galaxies
 All the contents of intergalactic
space
A Planet
 Most
scientist agree that a planet:
a star – such as the Sun
 Is round - due to the strength of its
own gravitational pull
 Orbits
Galaxies
single stars – includes:
Stars, Gas, and Dust
Variety of shapes, sizes, and
colors
Clustered in Groups
Gravitationally attracted/held
together
 NOT
Galaxies
Milky
Way = part of Local
Group
5 million light years across
In 1999 HST
est. 125 billion galaxies;
HST found 3,000 visible
galaxies in space
(Hubble Space Telescope)
Galaxies
Spiral = Milky Way
 Stars
form “arms”,
curve out from
center, disk or
pancake shaped
 Holds old & young
stars, gas, & dust
http://www.hdwallpapers.com/photo/Space_pictures/Spiral_Galaxy_M81
Galaxies
Elliptical
 Stars
form
shape like a
football
http://www.astronet.ru/db/xware/msg/1226180
Galaxies
Irregular
 No special
shape = blobs
w/threads
 Holds large
amount of
gas and dust
http://apod.nasa.gov/apod/ap081229.html
Stars
Large ball of gas that
creates & emits its
own radiation

Variety of shapes,
sizes, and colors
 Nebula, Main
Sequence, Red &
Super Giants,
White Dwarf,
Brown Dwarf, &
Supernova

UM = Magnitude =
degree of brightness
Lifecycle – NO
star lives forever
 Born,
Matures,
Grows old, &
Dies
Nebula – dense region
inside begins to
shrink, warm up,
becomes a protostar
http://www.calvin.edu/academic/phys/observatory/images/Astr110.Fall2006/deLa
nge.html
A Star is born

Protostar – critical
temperature is
reached – hydrogen
begins fusing into
helium
http://photojournal.jpl.nasa.gov/
Once a star is born it becomes a

Main Sequence Star
– shines as nuclear
reactions inside
produce light and
heat
http://www.for68.com/new/2005/12/su86402129331912150024200-0.htm

But if it doesn’t have
enough mass to
produce radiant heat
it becomes a Brown
Dwarf
http://dsc.discovery.com/news/2009/04/20/brown-dwarf-cool.html
At this point Stars can become a Super
Giant or Red Giant
Super Giant

Star of greater mass
Expands, cools, &
turns red
http://apod.nasa.gov/apod/ap001222.html
Super Giant EXPLODES
blasting away outer
layers becoming a
Super Nova
http://news.discovery.com/space/beautiful-supernova-violence.html
Supernova can become either:
Neutron Star –
core collapses &
becomes very dense
http://www.science.psu.edu/news-and-events/2007-news/Fox8-2007.htm
Black Hole – core
collapses
completely &
vanishes
http://www.nasa.gov/mission_pages/chandra/multimedia/photo09-078.html
If a Star becomes a Red Giant, then
Red Giant – star
of less mass
expands, glows red
as it cools, then
http://smithsonianscience.org/2010/03/archaeological-%E2%80%9Cdig%E2%80%9D-in-outerspace-uncovers-an-ancient-star/
Planetary Nebula
– outer layer of gas
puff off; hot core will
be white dwarf
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-astro-nebula.html
Red Giant =Planetary Nebula = White
Dwarf = White Dwarf Cooling
White Dwarf –
very dense, almost
transparent
http://www.jpl.nasa.gov/news/features.cfm?feature=576
White Dwarf
Cooling – takes
billions of years to
cool then fades to
black
http://imagine.gsfc.nasa.gov/docs/science/know_l1/dwarfs.html
Cooling White Dwarf = Black Dwarf
Black Dwarf - A
non-radiating ball
of gas; star stops
glowing
http://news.discovery.com/space/intermediate-black-hole-implicated-in-stars-death.html