Light Year This is a DISTANCE not an amount of TIME This is a DISTANCE not an amount of TIME EX: 3 Miles is a distance, 3 Years is a time EX: 3 Miles is.

Light YearLight YearThis is a This is a DISTANCEDISTANCE not an amount of not an amount of TIMETIMEEX: 3 Miles is a distance, 3 Years is a EX: 3 Miles is a distance, 3 Years is a timetimeUsed to represent extremely LARGE Used to represent extremely LARGE distance in spacedistance in spaceRemember, Light is a Transverse Wave – Remember, Light is a Transverse Wave – and all waves travel, they don’t just appearand all waves travel, they don’t just appear

So how far is it?So how far is it?

This distance is very large – it’s hard This distance is very large – it’s hard for the mind to understand how far for the mind to understand how far this isthis is

Speed of Light = 300,000 km/secSpeed of Light = 300,000 km/secThat’s about 18,000,000 km/minThat’s about 18,000,000 km/min

So how far is it?So how far is it?

Speed of light is about 186,000 Speed of light is about 186,000 miles/secmiles/sec

That is about 671,000,000,000,000 That is about 671,000,000,000,000 miles per hour (671 Trillion mph)miles per hour (671 Trillion mph)

So how far is it?So how far is it?

Now that you know how fast light Now that you know how fast light travels it time think about distancetravels it time think about distance

If we look at how far light would travel If we look at how far light would travel for ONE full year – that distance is a for ONE full year – that distance is a Light Year!Light Year!

One Full YearOne Full Year

The total distance light travels in one The total distance light travels in one full year is about: 9,460,000,000,000 full year is about: 9,460,000,000,000 km (9.46 trillion km)km (9.46 trillion km)

In terms of miles that is about: In terms of miles that is about: 5,800,000,000,000 miles (5.80 trillion 5,800,000,000,000 miles (5.80 trillion miles)miles)

An example close to home…An example close to home…So how far is that distance of a light So how far is that distance of a light

year… really.year… really.EX: it is about 370,000 km from the Earth EX: it is about 370,000 km from the Earth

to the Moon. If you could walk from the to the Moon. If you could walk from the Earth to the Moon, how many times would Earth to the Moon, how many times would you have to go that distance to equal a you have to go that distance to equal a light year?light year?

ANSWER: about ANSWER: about 12 MILLION12 MILLION times back times back and forth from the Earth to the Moon!and forth from the Earth to the Moon!

The Universe: Galaxies, The Universe: Galaxies, Stars, and NebulaeStars, and Nebulae

March 3, 2011March 3, 2011

The UniverseThe Universe

All physical matter and energy that All physical matter and energy that exist in space: exist in space: PlanetsPlanetsStars Stars GalaxiesGalaxiesAll the contents of intergalactic All the contents of intergalactic

spacespace

A PlanetA Planet

Most scientist agree that a planet:Most scientist agree that a planet:

Orbits a star – such as the SunOrbits a star – such as the SunIs round - due to the strength of its Is round - due to the strength of its

own gravitational pullown gravitational pull

GalaxiesGalaxiesNOT single stars – includes: NOT single stars – includes:

Stars, Gas, and DustStars, Gas, and DustVariety of shapes, sizes, and Variety of shapes, sizes, and

colorscolorsClustered in GroupsClustered in GroupsGravitationally attracted/held Gravitationally attracted/held

togethertogether

GalaxiesGalaxiesMilky Way = part of Milky Way = part of Local Local

GroupGroup5 million light years across5 million light years acrossIn 1999 HST In 1999 HST (Hubble Space Telescope)(Hubble Space Telescope) est. 125 billion galaxies; est. 125 billion galaxies; HST found 3,000 visible HST found 3,000 visible galaxies in spacegalaxies in space

GalaxiesGalaxies

SpiralSpiral = Milky = Milky WayWay

Stars form “arms”, Stars form “arms”, curve out from curve out from center, disk or center, disk or pancake shapedpancake shaped

Holds old & young Holds old & young stars, gas, & duststars, gas, & dust

http://www.hdwallpapers.com/photo/Space_pictures/Spiral_Galaxy_M81

GalaxiesGalaxies

EllipticalElliptical

Stars form Stars form shape like a shape like a footballfootball

http://www.astronet.ru/db/xware/msg/1226180

GalaxiesGalaxies

IrregularIrregularNo special No special

shape = blobs shape = blobs w/threadsw/threads

Holds large Holds large amount of gas amount of gas and dustand dust

http://apod.nasa.gov/apod/ap081229.html

StarsStarsLarge ball of gas that Large ball of gas that

creates & emits its creates & emits its own radiationown radiation

Variety of shapes, Variety of shapes, sizes, and colorssizes, and colorsNebula, Main Nebula, Main

Sequence, Red & Sequence, Red & Super Giants, Super Giants, White Dwarf, White Dwarf, Brown Dwarf, & Brown Dwarf, & SupernovaSupernova

UM = MUM = Magnitude agnitude = = degree of brightnessdegree of brightness

Lifecycle – NO Lifecycle – NO star lives foreverstar lives foreverBorn, Matures, Born, Matures,

Grows old, & Grows old, & DiesDies

Nebula Nebula – dense – dense region inside begins region inside begins to shrink, warm up, to shrink, warm up,

becomes a protostarbecomes a protostar

http://www.calvin.edu/academic/phys/observatory/images/Astr110.Fall2006/deLange.html

A Star is bornA Star is born

ProtostarProtostar – – critical temperature is critical temperature is reached – hydrogen reached – hydrogen begins fusing into begins fusing into heliumhelium

http://photojournal.jpl.nasa.gov/

Once a star is born it becomes aOnce a star is born it becomes a Main Sequence StarMain Sequence Star

– shines as nuclear – shines as nuclear reactions inside reactions inside produce light and produce light and heatheat

But if it doesn’t have But if it doesn’t have enough mass to enough mass to produce radiant heat produce radiant heat it becomes a it becomes a

Brown Dwarf Brown Dwarf

http://www.for68.com/new/2005/12/su86402129331912150024200-0.htm http://dsc.discovery.com/news/2009/04/20/brown-dwarf-cool.html

At this point Stars can become a Super At this point Stars can become a Super Giant or Red GiantGiant or Red Giant

Super GiantSuper Giant Star of greater mass Star of greater mass

Expands, cools, & Expands, cools, & turns redturns red

Super GiantSuper Giant EXPLODES EXPLODES blasting away outer blasting away outer layers becoming a layers becoming a

Super NovaSuper Nova

http://apod.nasa.gov/apod/ap001222.html http://news.discovery.com/space/beautiful-supernova-violence.html

Supernova can become either:Supernova can become either:

Neutron StarNeutron Star – core collapses & – core collapses & becomes very densebecomes very dense

Black HoleBlack Hole – core – core collapses collapses completely & completely & vanishesvanishes

http://www.science.psu.edu/news-and-events/2007-news/Fox8-2007.htm http://www.nasa.gov/mission_pages/chandra/multimedia/photo09-078.html

If a Star becomes a Red Giant, thenIf a Star becomes a Red Giant, then

Red GiantRed Giant – – star of less mass star of less mass expands, glows red expands, glows red as it cools, thenas it cools, then

Planetary Planetary Nebula Nebula – outer – outer layer of gas puff off; layer of gas puff off; hot core will be white hot core will be white dwarfdwarf

http://smithsonianscience.org/2010/03/archaeological-%E2%80%9Cdig%E2%80%9D-in-outer-space-uncovers-an-ancient-star/ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-astro-nebula.html

Red Giant =Planetary Nebula = Red Giant =Planetary Nebula = White White DwarfDwarf = = White Dwarf CoolingWhite Dwarf Cooling

White DwarfWhite Dwarf – very dense, almost – very dense, almost transparent transparent

White Dwarf White Dwarf CoolingCooling – takes – takes billions of years to billions of years to cool then fades to cool then fades to blackblack

http://www.jpl.nasa.gov/news/features.cfm?feature=576 http://imagine.gsfc.nasa.gov/docs/science/know_l1/dwarfs.html

Cooling White Dwarf = Black DwarfCooling White Dwarf = Black Dwarf

Black DwarfBlack Dwarf - -

A A non-radiating ball non-radiating ball of gas; star stops of gas; star stops glowingglowing

http://news.discovery.com/space/intermediate-black-hole-implicated-in-stars-death.html