Classifying Galaxies

Start of Lesson

What is a galaxy?

A galaxy is made of billions of stars, dust, and gas all heldtogether by gravity. Galaxies are scattered throughout theUniverse. They vary greatly in size and shape. Not allgalaxies look alike.

              This is a galaxy.               

 This is a galaxy.      

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                  This is also a galaxy   

Did you notice that these galaxy pictures don't look alike?

When telescopes led to the discovery of galaxies, astronomers observedmany differences.

In 1926, an astronomer named Edwin Hubble decided to classify the galaxies, grouping them accordingto some logical scheme.

He could have classified them according to color, because galaxies are different colors. Youcan see many different colored galaxies in the Hubble Deep Field image.

      He could have classified them according to size, callingsmall galaxies "dwarf galaxies" and calling large galaxies"massive galaxies".

After considering different schemes, he decided to arrange orgroup them by shapes. He would classify them according to theway they looked. In science, the study of something according toits form or structure is called "morphology".g

galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxygalaxyLet's consider the three galaxies we saw earlier. They are

typical of the three main types of galaxies that Hubble classified.

The first type of galaxy you saw is an elliptical galaxy. The word ellipticalrefers to its degree of "roundness". Hubble used the letter "E" to stand forelliptical galaxies.To see elliptical galaxies, click on the Galaxy Guide.        

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Galaxy Guide by Josh Kennedy

galaxy galaxy glalxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxygalaxy

galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy

         Hubble called the second type of galaxy you saw a  spiral galaxy. Itreminded him of a pinwheel or whirlpool. He used the letter "S" to stand forspiral galaxies.

         To see spiral galaxies, click the Galaxy Guide.

galaxy galaxy glalxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxygalaxy galaxygalaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy

     The third type of galaxy reminded Hubble of a spiral with asolid bar across the center. He called it a barred spiral galaxy.He used the letters "SB" to stand for barred spirals.

To see barred spiral galaxies, click on the Galaxy Guide       

ga

l

Many galaxies have strange, irregualr shapes, and do not fit neatly into any of these three categories.

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To see an example of a nearby irregular galaxy, click on the Galaxy Guide.     

Can you name the three main types of galaxies? Did you discover that each main typeis divided into smaller groups?           Click here to review.

To show the relationship of the galactic shapes, Edwin Hubble arranged the main types ofgalaxies and the sub-types into a chart that has come to be called "The Tuning ForkDiagram".

The Hubble "Tuning Fork Diagram" is the simplest way to classify galaxies. When you lookat a picture of a galaxy, and try to classify it, you are trying to place it on the diagram whereit belongs.

You have seen some pictures of galaxies in this lesson and have looked at how they wereclassified. Now it's time for you to classify some galaxy pictures. Are you up to the

challenge? Click here.   

NOTE: You must have a java-enabled browser in order for the next page to work. If yourbrowser does not work with java applets, Click here.

The Hubble Telescope has looked far into space and discovered manygalaxies. Travel to the Hubble Space Telescope Institute to look at animage of a newly discovered galaxy. See if you can classify it by itsshape.

Read the summary written below the picture to see if you were correct!Use the Back button at the top of your Web Browser to return herewhen you have finished your visit to Space Telescope Science Institute.

Space Telescope Science Institute

   The Hubble Space Telescope is making frequent new

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discoveries. If you want to do more galaxy exploring at theHubble Space Telescope Institute,     Click Here

Use the Back button at the top of your Web Browser toreturn here when you have finished your visit to SpaceTelescope Science Institute.

Now that you have had practice at classifying galaxies according to shape,you are ready to take the challenge of becoming a member of the HubbleDeep Field Academy.

 Remember this picture?   

This image was taken by the Hubble Space Telescopein December of 1995. It shows lots of previouslyunknown galaxies of different colors, shapes, andsizes. 

Use this link to the "Cosmic Classifier" to test yournew skill at classifying galaxies in the Hubble DeepField image.

Want to find out more about Edwin Hubble's Classification system? Click onthe obsrvatory dome!

Are you ready to go galaxy hopping on yourown?    Explore these astronomy links!

   What is this? Click on the image to find out!      

    Something mysterious at the heart of an elliptical galaxy!

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  How many galaxies can you see here? Click on the image to enlarge it.

How many different galaxy classifications identify in this picture?

Click you your back-arrow to come back here when you have finished.

Click here for late-breaking galactic news!

 

comments to George & Jane Hastings

this page last updated November 25, 1998

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Classifying Galaxies

Edwin Hubble at the 100 inch Telescope

     Edwin Hubble (1889-1953) guides the exposure of aphotographic plate at the Newtonian focus of the100-inch telescope in 1923. With this telescope, Hubblemeasured the distances and velocities of galaxies, workwhich led to today's concept of an expanding Universe.According to this profound idea, the Universe began tento twenty billion years ago with a Big Bang. Thereceding galaxies that Hubble observed trace theexpansion of space from that dense beginning. Thetelescope is a mechanical masterpiece and was dedicatedas an International Historical Mechanical EngineeringLandmark on June 20, 1981, by the American Society ofMechanical Engineers, only the fourth such award

granted in the United States.

     Edwin Hubble grew up in Wheaton, Illinois, a suburb of Chicago.

                                               For a complete biography, click here.

      Before he went on to become a famous astronomer, Edwin Hubble taughtSpanish and physics as well as coached basketball at New Albany High School,Indiana, in 1914. The New Albany High School Yearbook "Vista" was dedicated tohim.

     Look at the dedication page of the 1914 NAHS yearbook  to see a picture ofCoach Hubble and the winning basketball team, then use the back arrow at the topof your browser to return here.

For more information about Edwin Hubble and his system of galaxy classificationClick Here, then use the back arrow at the top of your browser to return here.

This page last updated December 12, 1997

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Edwin Hubble at the 100 inch telescope

http://world.smv.mus.va.us/~hastings/edwin1.htm [5/25/1999 12:34:03 PM]

Classifying Galaxies

Elliptical Galaxies

Most galaxies are elliptical. Some elliptical galaxies are nearly circular in shape.Some elliptical galaxies are extremely stretched out, flattened,or elongated. To dealwith this variation, Hubble divided the "E" classification into 8 sub-groups, which hecalled "E0", "E1", "E2", "E3", "E4", "E5", "E6", and "E7".

E0 galaxies are nearly circular in shape. E1 galaxies are stretched out a little. E2galaxies are more elongated, E3 galaxies even more elongated or flattened, all the way up to E7galaxies, which are extremely elongated or stretched out.

Look at these examples:"E1", "E2", "E3", "E4", "E5".

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Elliptical Galaxies

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Classifying Galaxies

Spiral Galaxies

When you looked at elliptical galaxies you saw that as the classification numbers progressed fromE1 toward E7, their appearance was more and more flattened or elongated. Edwin Hubbleobserved other galaxies that were elongated, but they were different from elliptical galaxiesbecause they had bright centers. He called the bright centers of galaxies "nuclei". He noted thatmany galaxies with bright nuclei also had "arms" spiraling out from the middle. He called thesegalaxies with bright nuclei "spiral galaxies".

Hubble named the galaxies that had bright nuclei but no spiral arms "S0"(S-zero)  galaxies.

He classified galaxies with spiral arms into three sub-groups that described how tightlythe arms were wound around the nucleus. Hubble called spirals with their arms wound

tightly around the nucleus, type "Sa". He called spirals with their arms less tightly wound (that is,looser and looser) "Sb" and "Sc". Here are examples of these types of spiral galaxies.

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Spiral Galaxies

http://world.smv.mus.va.us/~hastings/sprlmain.htm [5/25/1999 12:34:11 PM]

Classifying Galaxies

Barred Spirals

In about a third of spiral galaxies, the arms spiral out, not from the center, but from astraight bar of stars, gas, and dust that extends from both sides of the bright nucleus.Hubble classified these barred spirals into sub-groups "a" to "c" in order of increasingopenness of the arms, but with a "B" for barred inserted: "SBa", "SBb", "SBc".Here are examples of these three sub-groups of barred spiral galaxies.

A new image from the Hubble telescope first posted on "Astronomy Picture of theDay" reveals a barred spiral galaxy with a starburst ring near its center, where new

stars are being formed.

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This page last updated June 14, 1995

Barred Spiral Galaxies

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     Irregular Galaxies              Large Magellenic Cloud

courtesy David Malin (© Anglo-Australian Telescope Board).

    Galaxies that can't be classified aseither spiral or elliptical are calledirregular galaxies. Every irregulargalaxy is unique. It doesn't look likeany other galaxy. It just isn't a spiralor an elliptical.

Irr I galaxies have lots of young stars,gas, and dust, but do not have spiralarms.

Irr II galaxies look strange. It seemslikely that Irr II galaxies have beendistorted by collisions with othergalxies at some time in their history.

South of the Equator, it is possible tosee the Large and Small Magellanic Clouds, the two irregular galaxies closest to our own Milkey WayGalaxy. Astronomers predict that they will eventually collide with the Milkey Way and be incorporatedinto our own galaxy.

   Return to lesson

Page last updated April 3, 1998

Irregular Galaxies

http://www.smv.mus.va.us/~hastings/irreg.htm [5/25/1999 12:34:41 PM]

Classifying Galaxies

Hubble Tuning Fork Diagram

This chart shows all of the classifications of different shapes of galaxies. S0 is an extra categorythat Hubble used to describe the shape of galaxies that were about halfway between ellipticalgalaxies and spiral galaxies. E = Elliptical, S = Spiral, SB = Barred Spiral.

BACK

Hubble Tuning Fork Diagram

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Classifying Galaxies

Instructions for Classification

     

Rotating Spiral Galaxy animation by Josh Kennedy

Look at the rotating galaxy and then at the Hubble Tuning Fork Diagram next to it. Edwin Hubble wouldhave classified this galaxy as type Sa. Notice its well defined center and spiral arms.

On the next page, you will have a chance to classify some unidentified galaxies, and use your mouse toplace the galaxy images on the Hubble Tuning Fork Diagram. To move the galaxy pictures onto theHubble Tuning Fork Diagram you will:

put your mouse pointer on a galaxy image●

hold down the mouse button●

while holding down the button, move your pointer to a spot on the diagram●

release the mouse button●

When you release the mouse button, the galaxy image will move to the spot you have selected. If youwish to move it again, you can follow the same directions. When you have finished placing all the galaxyimages on the diagram, check your work by clicking on the the Galaxy Guy.

Start Here: Classifying galaxies

Page last updated on May 29, 1997

Instructions for Classification Test

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Classifying Galaxies

Classification Check

Congratulations on the completion of your first galaxy classification!

Now you are ready to attempt a more advanced assignment at the Space Telescope Institute.

   Click here

Classification Check

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Discovery of a Nearby Spiral Galaxy Behind theMilky WayR.C. Kraan-Korteweg (Groningen), A.J. Loan (Cambridge), W.B. Burton (Leiden) O. Lahav(Cambridge), H.C. Ferguson (STScI), P.A. Henning (Univ. New Mexico), D. Lynden-Bell (Cambridge)

Color image of Dwingeloo 1 from the Isaac Newton Telescope

The full paper (100 Kb postscript file) appears in Nature, November 3 1994.

SummaryThe disk of the Milky Way contains a lot of gas and dust, which obscures about 20% of the extragalacticsky. Galaxies hidden behind the Milky Way may have an important influence on the dynamics of theLocal Group and its peculiar motion relative to the cosmic microwave background radiation. Here wereport the discovery of a large spiral galaxy, which we call Dwingeloo 1, during the course of a searchfor emission from atomic hydrogen (HI) associated with galaxies hidden by the disk of the Milky Way --such emission is not obscured by the disk if the velocity of the emission differs from that of the local gas.The new galaxy seems to be associated with the group containing IC342 and the Maffei galaxies, and asubsequent optical image suggests that it is of type SBb. The detection of Dwingeloo 1 early in thecourse of this survey suggests that many more galaxies hidden behind the Milky Way remain to bediscovered. Harry Ferguson ferguson@stsci.edu

Dwingeloo 1

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Hubble SpaceTelescopeImages

by Subject

See links with thumbnail images

Solar System●

Stars●

Nebulae●

Star Clusters●

Novae and Supernovae●

Stellar Evolution●

Nearby Galaxies●

Distant Galaxies●

Quasars (QSOs)●

Cosmology (The Universe)●

Catalog Numbers●

General

Solar SystemVenus■

Mars■

Jupiter and its satellites■

Saturn, its rings and satellites■

Uranus, its rings and satellites■

Neptune■

Pluto/Charon■

Comets■

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HST Imagesby Subject

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Asteroids (Minor Planets)■

Other■

VenusVenus in Ultraviolet Light■

MarsColossal Cyclone Swirls Near Martian North Pole■

Martian Colors Provide Clues about Martian Water■

Hubble Watches The Red Planet As Mars Global Surveyor Begins Aerobraking■

Hubble Sees Rapid Weather Changes On Mars■

Pathfinder Landing Site on Mars■

Hubble Finds Cloudy, Cold Weather Conditions For Mars-Bound Spacecraft■

Hubble's Sharpest View Of Mars■

Springtime Dust Storm Swirls At Martian North Pole■

Mars at Opposition■

Jupiter and its satellitesHubble Clicks Images of Io Sweeping Across Jupiter■

Hubble Provides Complete View Of Jupiter's Auroras■

Hubble Provides Infrared View Of Moon, Ring, And Clouds■

Hubble Captures Volcanic Eruption Plume From Io■

Hubble Follows Rapid Changes In Jupiter's Aurora■

Rare Hubble Portrait Of Io And Jupiter■

Galileo Probe Target■

Changes on Io's Surface■

Jupiter's Galilean Satellites■

Jupiter Storms■

Jupiter G Impact Evolution■

Oxygen on Jupiter's Moon Europa■

Evolution of Comet/Jupiter Impacts■

HST Imagesby Subject

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Comet/Jupiter Encounter■

Jupiter and Io■

Saturn, its rings and satellitesTelescope Completes Eighth Year Of Exploration■

Hubble Provides Clear Images Of Saturn's Aurora■

Saturn Ring-Plane Crossing, November 1995■

Saturn Ring-Plane Crossing, November 1995■

Saturn Ring-Plane Crossing, August 11, 1995■

New Satellites of Saturn■

Saturn Ring-Plane Crossing, May 22, 1995■

New Saturn Storm■

Surface of Titan■

Uranus, its rings and satellitesHuge Spring Storms Rouse Uranus from Winter Hibernation■

Hubble Finds Many Bright Clouds On Uranus (STScI-PR98-35)■

Hubble Space Telescope Helps Find Evidence that Neptune’s Largest Moon isWarming Up (STScI-PR98-23)

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Hubble Watches Uranus■

Color image of Uranus■

Uranus: Rings, Satellites and Clouds■

NeptuneHubble Helps Find Evidence that Neptune’s Largest Moon is Warming Up(STScI-PR98-23 June 24, 1998)

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Hubble Provides A Moving Look At Neptune's Stormy Disposition(STScI-PR98-34)

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Hubble Makes Movie Of Neptune's Rotation And Weather■

New Neptune Clouds■

Neptune■

HST Imagesby Subject

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Pluto and CharonSurface of Pluto■

Pluto and Charon■

CometsComet Hyakutake • C/1996 B2■

Hale-Bopp Observations with Hubble and IUE Suprise Astronomers■

Comet Hyakutake■

Comet Hale-Bopp■

Kuiper Belt Comets■

Evolution of Comet/Jupiter Impacts■

Comet/Jupiter Encounter■

Comet P/Shoemaker-Levy 9 (1993e)■

Asteroids (Minor Planets)A Mote in Hubble's Eye (STScI-PR99-08)■

Astronomers Track Down Asteroids in Hubble Archive (STScI-PR98-10)■

Maps of Asteroid Vesta's Surface (STScI-PR95-40)■

Asteroid Vesta (STScI-PR95-20)■

Other Solar System ObjectsHubble Shoots the Moon■

Leonid Meteor Storm■

Kuiper Belt Comets■

Gas Cloud Around the Sun■

StarsVast Stellar Disks Set Stage for Planet Birth in New Hubble Images■

Dust Ring Around Star Offers New Clues Into Planet Formation■

Gap In Stellar Dust Disk May Be Swept Out By Planet■

HST Imagesby Subject

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Behind a Dusty Veil Lies a Cradle of Star Birth■

Great Balls of Fire! Hubble Sees Bright Knots Ejected From Brilliant Star■

Hubble Finds That Even Massive Stars Just Fade Away■

A New Class Of X-ray Star?■

New Twist In A Suspected Protoplanetary Disk■

Hubble Captures Brief Moment In Life Of Lively Duo■

Hubble Catches Up with a Blue Straggler Star■

Newly Identified Star May Be Most Luminous Known; May Once Have Been theMost Massive

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Hubble Sees a Neutron Star Alone in Space■

Blobs in Space: The Legacy of a Nova■

Hubble Separates Stars In The Mira Binary System■

Hubble Finds Intergalactic Stars■

Supernova Blast Begins Taking Shape■

Brown-Dwarf Binary System■

Black-hole Candidate: Victim of Mistaken Identity■

Warped disk of Beta Pictoris■

Atmosphere of Betelgeuse■

Brown Dwarf Gliese 229B■

Edge-On disk of Beta Pictoris■

Low-Mass Companion to Gl105a■

White Dwarf Stars in M4■

Cataclysmic Variable Star■

Stellar Jets and Disks■

Inside Red Dwarfs■

Small Star■

NebulaeMultiple Generations of Stars in the Tarantula Nebula■

SN1987A in the Large Magellanic Cloud■

Looking Down a Barrel of Gas at a Doomed Star■

A Glowing Pool of Light■

HST Imagesby Subject

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Hubble Provides Multiple Views of How to Feed a Black Hole■

Great Balls of Fire! Hubble Sees Bright Knots Ejected From Brilliant Star■

Turtle in Space Describes New Hubble Image■

Newly Born Planetary Nebula■

Hubble Captures Shrouds of Dying Stars (STScI-PRC-98-11)■

Final Blaze Of Glory Of Sun-Like Stars■

Newly Identified Star May Be Most Luminous Known; May Once Have Been theMost Massive

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NICMOS Peers Into Heart Of Dying Star■

NICMOS Captures The Heart Of OMC-1■

Hubble Camera Resumes Science Operation With Picture Of "Butterfly" In Space■

Giant "Twisters" and Star Wisps in the Lagoon Nebula■

Destruction of Proto-Planetary Disks in Orion's Trapezium Explained■

Crab Nebula -- The Movie■

Helix Nebula■

Planetary Nebula NGC 7027■

Hourglass Nebula■

Egg Nebula■

Orion Nebula Mosaic■

Star Birth in M16■

Cygnus Loop■

Planetary Nebula NGC 6543■

``Proplids'' in Orion Nebula■

Star ClustersNearby Massive Star Cluster Yields Insights into Early Universe (STScI-PR98-25)■

Hubble Finds That Even Massive Stars Just Fade Away■

Hubble Catches Up with a Blue Straggler Star■

Hubble Reveals Stellar Fireworks Accompanying Galaxy Collisions■

Globular Cluster GC1 in M31■

Dense Globular Cluster M15■

White Dwarf Stars in M4■

HST Imagesby Subject

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Star Birth in NGC 1850■

Novae and SupernovaeSN1987A in the Large Magellanic Cloud■

Shock Wave Shed New Light On Fading Supernove■

Hubble Pinpoints Distant Supernovae■

Blobs in Space: The Legacy of a Nova■

STIS Reveals Invisible High-Speed Collision Around Supernova 1987A■

STIS Chemically Analyzes The Ring Around Supernova 1987A■

Supernova Blast Begins Taking Shape■

Doomed Star Eta Carinae■

Crab Nebula -- The Movie■

Oxygen-Rich Supernova Remnant in the Large Magellanic Cloud■

Supernova 1987A Rings■

Supernova in Galaxy M51■

Nova Cygni 1992■

Stellar EvolutionVast Stellar Disks Set Stage for Planet Birth in New Hubble Images■

Behind a Dusty Veil Lies a Cradle of Star Birth■

Great Balls of Fire! Hubble Sees Bright Knots Ejected From Brilliant Star■

Nearby Massive Star Cluster Yields Insights Into Early Universe■

Hubble Catches Up with a Blue Straggler Star■

Blobs in Space: The Legacy of a Nova■

Hubble Snaps "Family Portrait"■

Destruction of Proto-Planetary Disks in Orion's Trapezium Explained■

Hubble Census Tracks A Stellar "Baby Boom"■

Bright Starbirth Region In A Dim Galaxy■

Giant Starbirth Region In Neighboring Galaxy■

Helix Nebula■

Orion Nebula Mosaic■

HST Imagesby Subject

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Star Birth in M16■

"Proplyds'' in Orion Nebula■

Nearby GalaxiesRing Around a Galaxy (STScI-PR99-16)■

Hubble's Infrared Galaxy Gallery (STScI-PR99-10)■

Hubble Finds More Evidence of Galactic Cannibalism (STScI-PR99-06)■

Behind a Dusty Veil Lies a Cradle of Star Birth (STScI-PR98-42)■

Nearby Massive Star Cluster Yields Insights into Early Universe (STScI-PR98-25)■

Hubble Uncovers Dust Disk Around a Massive Black Hole (STScI-PRC98-22)■

A Bright Ring Of Star Birth Around A Galaxy's Core (STScI-PRC98-21)■

Hubble Provides Multiple Views of How to Feed a Black Hole■

Hubble Captures the Heart of Star Birth (STScI-PRC98-12)■

Dust in Spiral Galaxies■

Hubble Reveals Stellar Fireworks Accompanying Galaxy Collisions■

Hubble Finds A Bare Black Hole Pouring Out Light■

Fireworks in a Black Hole Near the Core of the Seyfert Galaxy NGC 4151■

A Collision in the Heart of a Galaxy■

STIS Records A Black Hole's Signature■

Massive Black Holes Dwell In Most Galaxies■

Hubble Spies Supersonic "Comet-Clouds" In Heart Of Galaxy■

Giant Starbirth Region In Neighboring Galaxy■

Hubble Constant Update■

Whirlpool Galaxy Nucleus■

Globular Cluster GC1 in M31■

Core of Galaxy NGC 4261■

Oxygen-Rich Supernova Remnant in the Large Magellanic Cloud■

Galaxy NGC 253■

Galaxy NGC 4881■

Cartwheel Galaxy Interactions■

Dwingeloo 1; Nearby Spiral Galaxy Behind Milky Way■

Cepheid Variables in M100■

HST Imagesby Subject

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Gas Disk in Active Galaxy M87■

Supernova 1987A Rings■

Supernova in Galaxy M51■

Galaxy M100■

Distant GalaxiesNatural Lenses in Space Stretch Hubble's View of the Universe (STScI-PR99-18)■

Combined Deep View of Infrared and Visible Light Galaxies (STScI-PR98-02)■

Hubble Goes To The Limit In Search Of Farthest Galaxies (STScI-PR98-32)■

Far-Flung Galaxy Clusters Expand Window into Early Universe (STScI-PR98-27)■

Distant Heavyweight Galaxy Cluster Clobbers Dense-Universe Theory(STScI-PR98-26)

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Hubble Finds Most Of Visible Light In The Universe■

World's Most Powerful Telescopes Team Up With A Lens In Nature To DiscoverFarthest Galaxy In The Universe

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Hubble Sees Early Building Blocks Of Today's Galaxies■

Hubble Deep Field Results: Distant Objects■

Gravitational Lens in Cluster Cl0024+1654■

Hubble Deep Field■

Cross-Shaped Gravitational Lenses■

HST Observes Radio Galaxies■

Faint Irregular Galaxies■

Gravitational Lens in Galaxy Cluster Abell 2218■

Galaxies in the Young Universe■

Quasars (QSOs)Quasar PG1115+080 and Gravitational Lens■

Hubble Surveys The "Homes" Of Quasars■

Hubble Achieves Milestone: 100,000th Exposure■

Cross-Shaped Gravitational Lenses■

Gravitational Lens in Galaxy Cluster Abell 2218■

HST Imagesby Subject

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Quasar PKS 2349■

QSO 1229+204■

Cosmology (The Universe)Hubble Completes Eight-Year Effort to Measure Expanding Universe(STScI-PR99-19)

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Natural Lenses in Space Stretch Hubble's View of the Universe (STScI-PR99-18)■

Combined Deep View of Infrared and Visible Light Galaxies (STScI-PR98-02)■

Far-Flung Galaxy Clusters Expand Window into Early Universe (STScI-PR98-27)■

Distant Heavyweight Galaxy Cluster Clobbers Dense-Universe Theory(STScI-PR98-26)

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Nearby Massive Star Cluster Yields Insights into Early Universe (STScI-PR98-25)■

Gamma-Ray Burst Found to be Most Energetic Event in Universe■

Hubble Pinpoints Distant Supernovae■

Infrared Background Glow in The Universe■

Hubble Stays On Trail Of Fading Gamma-Ray Burst Fireball■

World's Most Powerful Telescopes Team Up With A Lens In Nature To DiscoverFarthest Galaxy In The Universe

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Mysterious Fireball From a Cataclismic Explosion■

Hubble Pinpoints Optical Counterpart of Gamma Ray Burst in a Distant Galaxy■

Hubble Census Tracks A Stellar "Baby Boom"■

Hubble Sees Early Building Blocks Of Today's Galaxies■

Hubble Deep Field Results: Distant Objects■

Hubble Constant Update■

Cross-Shaped Gravitational Lenses■

Faint Irregular Galaxies■

Gravitational Lens in Galaxy Cluster Abell 2218■

Quasar PKS 2349■

Galaxies in the Young Universe■

HST Measures Precise Distance to the Most Remote Galaxy Yet■

Search for Dark Matter■

QSO 1229+204■

HST Imagesby Subject

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Catalog NumbersHubble Finds More Evidence of Galactic Cannibalism■

Looking Down a Barrel of Gas at a Doomed Star■

A Glowing Pool of Light■

Messier Non-Stellar Objects■

NGC Non-Stellar Objects■

Abell Galaxies■

Herbig-Haro Objects■

PKS Radio Galaxies■

Gliese Stars■

MessierM57 Looking Down a Barrel of Gas at a Doomed Star■

M1 Crab Nebula -- The Movie■

M4 White Dwarf Stars in M4■

M42 ``Proplids'' in Orion Nebula■

M51 Supernova in Galaxy M51■

M87 Gas Disk in Active Galaxy M87■

M100 Cepheid Variables in M100■

M100 Galaxy M100■

NGCNGC 891 Hubble's Infrared Galaxy Gallery■

NGC 2903 Hubble's Infrared Galaxy Gallery■

NGC 3593 Hubble's Infrared Galaxy Gallery■

NGC 4826 Hubble's Infrared Galaxy Gallery■

NGC 5653 Hubble's Infrared Galaxy Gallery■

NGC 6946 Hubble's Infrared Galaxy Gallery■

NGC 1316 Hubble Finds More Evidence of Galactic Cannabilism■

NGC 6720 Looking Down a Barrel of Gas at a Doomed Star■

NGC 3132 A Glowing Pool of Light■

HST Imagesby Subject

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NGC 5128 Hubble Provides Multiple Views of How to Feed a Black Hole■

NGC 253 Galaxy NGC 253

■ NGC 1808 Hubble Captures the Heart of Star Birth (STScI-PRC98-12)

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NGC 1850 Star Birth in NGC 1850■

NGC 4261 Cataclysmic Variable Star■

NGC 4881 Galaxy NGC 4881■

NGC 6397 Search for Dark Matter (STScI-PR94-41)■

NGC 6543 Planetary Nebula NGC 6543■

Abell Galaxy ClustersA2218 Gravitational Lens in Galaxy Cluster Abell 2218■

Herbig-Haro ObjectsStellar Jets and Disks■

PKS Radio GalaxiesHST Observes Radio Galaxies■

Quasar PKS 2349■

Gliese StarsBrown Dwarf Gliese 229B■

Low-Mass Companion to Gl105a■

Inside Red Dwarfs (Gl752b)■

Small Star (Gl623b)■

GeneralMaryland Science Center's "Space Place" Showcases Hubble Discoveries❍

Extraterrestrial Civilizations: Coming of Age in the Milky Way❍

NASA Selects Home For Next Generation Space Telescope❍

 

HST Imagesby Subject

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Additional PicturesMost Recent Public Images❍

1999 Releases❍

1998 Releases❍

1997 Releases❍

1996 Releases❍

1995 Releases❍

1994 Releases❍

First 1994 Post-Servicing Images❍

Pre-Servicing Mission Images❍

More InformationAbout these Images❍

Text of Press Releases❍

Additional Background Text❍

Animations❍

Public Outreach Home Page❍

Space Telescope Science Institute❍

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The Space Telescope Science Institute is operated by the Association of Universities for Research inAstronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt,MD. The Hubble Space Telescope is a project of international cooperation between NASA and theEuropean Space Agency (ESA).

Office of Public Outreach -- outreach@stsci.edu

 

Copyright© 1990-1999 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.

HST Imagesby Subject

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Educator wanted for Academic Year 1999-2000

The Space Telescope Science Institute's Office of Public Outreach is seeking a full time teacher from anyacademic level, grades 6-12, to participate in their Internship Program. The intern will be actively involvedin the development of interactive activities for the World Wide Web; as well as, conducting pilot programsto encourage partnerships and distribution of materials nationwide.

 

Amazing Space is a set of web-based activities primarily designed for classroom use, butmade available for all to enjoy.

Current activities include:

 

Amazing Space Web-Based Activities

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NEW IN '99: Play with the building blocks of the universe, galaxies, in Galaxies Galore

Find out what light and color can tell you about stars in Star Light, Star Bright

Learn about the objects that make up the Solar System by collecting Solar System Trading Cards

Train to be a scientist by enrolling in the Hubble Deep Field Academy.

Create a schedule for the Second Servicing Mission to upgrade the Hubble Space Telescopethrough the Astronaut Challenge.

Brief history of telescopes from Galileo to the Hubble Space Telescope.

Did An Activity? Tell us what you think.

Learn more about the Amazing Space project.

Press Releases and other information for the general public.

Visit the Space Telescope Science Institute

 

Copyright© 1990-1999 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.

Amazing Space Web-Based Activities

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The Life of Edwin Hubble(1889 - 1953)

Edwin Hubble was an American astronomer who made vital contributions to the studyof galaxies, establishing the existence of galaxies outside of the Milky Way andproving that the universe is expanding. For his revolutionary contributions to ourunderstanding of galaxies and of the scope of the universe, Hubble was recognized bythe astronomical community in 1983, thirty years after his death, when the SpaceTelescope was renamed in his honor.

Early Life and Education

Edwin Powell Hubble was born on November 20, 1889 in Marshfield, Missouri before the eyes of bothhis parents and his grandparents. At a young age, Hubble had a taste for books and an interest inastronomy, unlike many of the other great astronomers portrayed in these biographies.

A strong athlete in high school, Hubble received a scholarship from the University of Chicago but had towork hard nonetheless to pay the balance of his expenses. Perhaps his most interesting job during thistime was as a lab assistant to Robert Millikan -- well known for determining the charge of an electron inhis Nobel prize-winning oil drop experiment.

Hubble received his B.S. degree from the University of Chicago and was offered a Rhodes Scholarship tostudy law at Queens College in Oxford. Though Hubble started a law practice after returning to theUnited States, he abandoned his practice and returned to Chicago to study for his doctorate in astronomy,which he received the day before joining the army in 1917.

Hubble and the Observatory

It is difficult to find a photograph in which Edwin Hubble is not seen poised on a mammoth telescope inan observatory. From the time he began his doctorate work at the University of Chicago's YerkesObservatory in 1914 to his death, Hubble worked with many observatories and was influential in theconstruction of the largest ground-based telescope in the world.

Mount Wilson. After the First World War, Hubble was married to Grace Burke and began work at theMount Wilson Observatory with its 100-inch telescope. Above all, his research there demonstrated theneed for a larger telescope that could see farther. Hubble left Mount Wilson in 1942, off again to war,where he would be awarded a Medal of Merit in 1946, and returned again after the war to continue hisresearch.

Mount Palomar. Most of Hubble's work was done at the Mount Wilson Observatory, but he wasintimately involved with the Mount Palomar Observatory, part of the committee that oversaw its

The Online Planetarium Show: The Life of Hubble

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construction. Even more importantly, he advised and assisted in the construction of the Mount Palomar200-inch Hale telescope, where he can be seen perched in photos.

Hubble's "Island Universe" Theory

In the early 20th century, before Hubble began his extensive work, there was an intense debate raging inthe field of astronomy over great clusters of stars, called "nebulae." At the time, there was no evidencethat there were galaxies in the universe that lay beyond the Milky Way. At issue, then, was whether these"nebulae" were a part of the Milky Way or some other star formations beyond our galaxy. In some ways,it is more difficult to comprehend that the existence of other galaxies was uncertain in such recent yearsthan to believe that Copernicus was doubted in the 16th century for proposing the idea of a solar system.

Finally, Hubble determined that these "nebulae" are indeed other galaxies because they are moving awayfrom the earth. In fact, he concluded that these star systems are each "island universes," not part of ourown galaxy. This was an enormously important discovery, for it opened up a great new realm of researchand provided an important base for the theory of the expanding universe.

The Expanding Universe

When Hubble observed other galaxies moving away from Earth, he was lookingat the wavelengths of their light. If the wavelengths are longer and towards thered end of the spectrum, then the galaxy is going away from us; but if thewavelengths are shorter and bluish, then the galaxy is coming towards us. Laterin the Guided Tour, we will expand on the concepts of "redshifting" and"blueshifting." For now, it is enough to understand that he could prove that thesegalaxies were moving away from Earth.

Diagram. Red shift and Blue shift. Hubble used the wavelengths of light to determine whether galaxies were movingtowards or away from us. Galaxies with wavelengths in the red regions are moving away while those with wavelengths inthe blue regions are coming towards us. Original diagram by The Online Planetarium Show.

Another interesting aspect of Hubble's research was his discovery that more distant galaxies move awaymore quickly than those closer to us. The very notion that these galaxies were actually receding is animportant one because it is a central tenant of the Big Bang theory, in which a powerful explosioninitiates the inflation of the universe. Incredibly, Albert Einstein referred to Hubble's work as "beautiful"and adjusted his relativity equations to account for the fact that the universe is expanding!

Classification of Galaxies

Hubble's work classifying galaxies is hardly unimportant, yet it pales in comparison with his far-reachingdiscoveries. Hubble grouped galaxies into three main categories:

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Spirals -- with arms winding around a central nucleus; our Milky Way, for instance, is a spiral●

Ellipticals -- found in a variety of rounded shapes●

Irregulars -- come in plenty of peculiar forms●

Ever since, astronomers have been identifying galaxies as either spiral, elliptical or irregular. Though weregularly use these terms to describe galaxies and though this terminology is exceedingly important toastronomy, Hubble's name is only rarely mentioned, much less associated with these classifications.

Hubble's . . . Legacy?

When we speak of the telescope, Galileo's name frequently surfaces, for he popularized the instrumentfor astronomical purposes. For all of Edwin Hubble's incredible discoveries that are discussed in thisbiography -- particularly his proof of the very existence of galaxies outside of the Milky Way -- it wouldseem that the leaps in astronomy's understanding of the universe made by his work are comparable tothose made by the studies Galileo or Copernicus.

Yet for all of his accomplishments, Hubble's name is relatively obscure; even when we hear about theSpace Telescope that was named in his honor, we rarely learn about his contributions or life. Accordingto several biographers, he should be looked upon as an astronomer who "revolutionized" ourunderstanding of the universe -- much like Galileo or Copernicus. Perhaps in several hundred years wewill.

Return to "The Entrancing Mysteries of Space"...

Browse the Table of Contents...

Return to The Online Planetarium Show Homepage...

The Online Planetarium Show: The Life of Hubble

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Classifying Galaxies

Astronomy Links

Looking for more astronomy information?Try these links!

 

   Project Ceres - Classifying Galaxies

  Astronomy resources - this is excellent!

        Galaxies and Quasars 

  Hands On Universe: Galaxy Types

    Space Telescope Science Institute - These are links to information of generalinterest regarding the Hubble Space Telescope (HST) and the Space TelescopeScience Institute (ST ScI). This includes information or interest to educators,students, the media and the general public; pictures resulting from observations byHST instruments.

     young galaxies - Single image - part of the famous Hubble "Deep Field"

   

THE SCIENCE EDUCATION GATE-WAY! -  Learning adventures in Earth and Space science from aNASA-sponsored partnership of museums, researchers and educators. SEG-way is the public userinterface of the Science Information Infrastructure (SII), funded by NASA's Information Infrastructure

Galaxy Hot Links to other Astronomy Resources

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Technology and Applications (IITA), a component of the Federal High Performance Computing andCommunications program (HPCC).

    What is a galaxy? - To continue your study of galaxies, visit this site. It is a service of the HighEnergy Astrophysics Science Archive Research Center (HEASARC) at the NASA GoddardSpace Flight Center in Maryland.

StarChild: A learning center for young astronomers a COOL site for kids, includes Level I andLevel II sections on "The Solar System", "The Universe", "Space Stuff", and a Glossary.

Harvard Atlas of Galaxies - galaxy images in multiple wavelengths.

Links to Telescope Sites - Almost 300 observatories all over the world now maintain links on the worldwide web. Many of them have more information about galaxies.

  Students for the Exploration and Development of Space - Internet Space ArchiveLPL/Arizona. A large internet resource of Space related images, information and software.

The Interactive NGC Catalog Online - This is the interactive NGC (and IC, and Messier) catalog atSEDS (Students for the Exploration & Development of Space). It contains open and globular starclusters, diffuse and planetary nebulae, supernova remnants, galaxies of all types.

  Astronomical Society of the Pacific

    List of NGC Images

     NGC 5 through NGC 1982

     NGC 2023 through NGC 3995

     NGC 4027 through NGC 5904

     NGC 6093 through NGC 7793

     Appendix: NGC Additions

Information Infrastructure Technology and Applications - Multimedia libraries at your fingertips.Remote sensing databases of the earth and the universe easily accessible to everyone. Classrooms on theInternet allowing students to interact with scientists and engineers while they work. A project of theNational Aeronautics and Space Administration (NASA), IITA is working on all of this and more byfunding fifty different programs. Explore this site and learn what the future holds for you!

Multiwavelength Atlas of Galaxies - Education and Outreach - This atlas of spiral and elliptical galaxiescontains images that span the optical, X-ray, Radio and Infrared regions of the electromagnetic spectrum.These images of galaxies provide important information about the stars, cold, warm and hot gas, dust andcharged particles that exist in each galaxy. If you are interested in background information about types ofgalaxies, or the origin of the radiation, links will give you this information at a high school orundergraduate level. Another link will lead you to web sites of the telescopes that took these images.

Astronomy Education Resources - AstroEd: K-12 Outreach Project, University of Washington

Galaxy Hot Links to other Astronomy Resources

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What's New Curriculum materials and on-line courses. Newsletters and magazines, Images andAnimations, History of Astronomy, Views of the Sky, Additional Astronomy Resources, Mirror Sites,NASA, Physics Resources, and Other Science Resources.

HEASARC/GSFC Home Page - High Energy Astrophysics Science Archive Research Center

Mount Wilson Observatory - Includes a "Virtual Tour" and sections on Science, Education, What's New,History, Services, and Requesting time on the 100" telescope.

Space Telescope Electronic Information Service - Search for Hubble Space Telescope images of nearbygalaxies or distant galaxies

   Space Hotlist  at NASA.

Lots of space links

 STAR HUSTLER Home Page

More Astronomy Links

 The WWW Virtual Library: Astronomy and Astrophysics

Astronomy (Science)

Astronomy Information Systems

The Galaxy Page

Harvard-Smithsonian Center for Astrophysics

Harvard-Smithsonian Theoretical Astrophysics Group

International Journal of Solar System Exploration

Archive-name: astronomy/ftp-sites

The sci.astro FAQ

Galaxy Hot Links to other Astronomy Resources

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NASA Technical Report Server (NTRS)

Search the NASA High Energy Astrophysics Science Archives

More Space Science Links on the World Wide Web

Close Encounters: a new lesson by George Hastings - under construction

Number of times this page has been accessed since November 17, 1998

Galaxy Hot Links to other Astronomy Resources

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Astronomy Picture of the DayDiscover the cosmos! Each day a different image or photograph of our fascinating universe is featured,

along with a brief explanation written by a professional astronomer.

March 26, 1998

Galaxies AwayCredit: W. Keel and R. White (U. Alabama), NASA

Explanation: This striking pair of galaxies is far, far away ... about 350 million light-years from Earth.Cataloged as AM0500-620, the pair is located in the southern constellation Dorado. The backgroundelliptical and foreground spiral galaxy are representative of two of the three major classes of galaxieswhich inhabit our Universe. Within the disks of spiral galaxies, like our own Milky Way, gas, dust, and

APOD: March 26, 1998 - Galaxies Away

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young blue star clusters trace out grand spiral "arms". The dust lanes along the arms of this particularspiral stand out dramatically in this Hubble Space Telescope image as they obligingly sweep in front ofthe background elliptical. Like the central bulges of spiral galaxies, elliptical galaxies tend towardspherical shapes resulting from more random motions of their stars. But while spirals produce new stars,star formation in ellipticals which lack gas and dust seems to have stopped. How do galaxies evolve withcosmic time? Evidence is growing that graceful galaxy shapes can hide a violent history.

< Archive | Index | Search | Calendar | Glossary | Education | About APOD >

Back to Classifying Galaxies

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)NASA Technical Rep.: Jay Norris. Specific rights apply.

A service of: LHEA at NASA/ GSFC&: Michigan Tech. U.

APOD: March 26, 1998 - Galaxies Away

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Astronomy Picture of the DayDiscover the cosmos! Each day a different image or photograph of our fascinating universe is featured,

along with a brief explanation written by a professional astronomer.

April 9, 1998

Quasar in an Elliptical GalaxyCredit: J. S. Dunlop, R. J. McLure (U. Edinburgh), HST, NASA

Explanation: Where do quasars live? Quasars are the brightest objects in the universe, so bright they canbe seen from across the universe. Observations continue to show that most quasars are surrounded by arelatively faint nebulous patch. Astronomers are trying to identify the nature of these patches. The abovefalse-color picture shows a central quasar embedded in an unusual elliptical galaxy. The galaxy is beinggravitationally distorted by a neighboring galaxy. Recent evidence indicates that most quasars live nearthe centers of large, elliptical galaxies - even those quasars where no host galaxy could be found before.Quasars themselves are thought to result from matter falling toward supermassive black-holes.

Tomorrow's picture: Comet Atmosphere

APOD: April 9, 1998 - Quasar in an Elliptical Galaxy

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< Archive | Index | Search | Calendar | Glossary | Education | About APOD >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)NASA Technical Rep.: Jay Norris. Specific rights apply.

A service of: LHEA at NASA/ GSFC&: Michigan Tech. U.

APOD: April 9, 1998 - Quasar in an Elliptical Galaxy

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Astronomy Picture of the DayDiscover the cosmos! Each day a different image or photograph of our fascinating universe is featured,

along with a brief explanation written by a professional astronomer.

September 29, 1998

A Peculiar Cluster of GalaxiesCredit: FORS1, 8.2-meter VLT, ESO

Explanation: Far across the universe, an unusual cluster of galaxies has been evolving. A diverse groupof galaxies populate this cluster, including, on the left, an unusual galaxy showing an equatorial polarring and a large spiral. Above looms a large elliptical galaxy. The reason for the small size of galaxies onthe right is not yet known - these galaxies might be smaller or might just lie even further in the distance.Almost every spot in this picture is a galaxy. Studying distant clusters like this may help astronomersbetter understand when and how these cosmic giants formed.

APOD: September 29, 1998 - A Peculiar Cluster of Galaxies

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Tomorrow's picture: In the Center of NGC 1232

< Archive | Index | Search | Calendar | Glossary | Education | About APOD >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)NASA Technical Rep.: Jay Norris. Specific rights apply.

A service of: LHEA at NASA/ GSFC&: Michigan Tech. U.

APOD: September 29, 1998 - A Peculiar Cluster of Galaxies

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THE UNIVERSE "DOWN UNDER" IS THE TARGET OF HUBBLE'S LATEST DEEP-VIEW

Turning its penetrating vision toward southern skies, NASA's Hubble Space Telescope has peered down a 12 billion light- yearlong corridor loaded with a dazzling assortment of thousands of never-before seen galaxies. The observation, called the HubbleDeep Field South (HDF-S), doubles the number of far-flung galaxies available to astronomers for deciphering the history of theuniverse.

See more details below the image.

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This new far-look complements the original Hubble "deep field" taken in late 1995, when Hubble was aimed at a small patch ofspace near the Big Dipper. The new region is in the constellation Tucana, near the south celestial pole.

The 10-day-long observation was carried out in October 1998 by a team of astronomers at the Space Telescope Science Institute(STScI), Baltimore, MD, and NASA's Goddard Space Flight Center, Greenbelt, MD. It is being made available today to theworldwide astronomy community for further research, and to the general public interested in the most distant reaches of thecosmos.

"The southern field promises to be the most studied area of the sky over the next five years," says STScI astronomer RobertWilliams, when as STScI Director, he used his discretionary time to undertake the first deep field campaign, and has overseenthe latest observation.

"We have eagerly awaited this new set of images ever since the first HDF, which had a dramatic impact on the entire science ofastronomy. Hubble's deep field views revealed a large, heretofore unseen fraction of the universe and opened it up tointerpretation and understanding."

It will take months for astronomers to digest what new secrets of the universe are within this latest look. At first glance theHDF-S appears to validate the common assumption that the universe should look largely the same in any direction.

The two deep fields now give astronomers two "core samples" of the universe for better understanding the history of thecosmos. The pair of observations can be compared to more confidently infer the state of the cosmos as a whole. It would takeastronomers 900,000 years to use Hubble to survey the entire sky to the depths of the HDF. So, they must rely on a thin,"looking-through-soda straw" view across the cosmos and infer the history of star and galaxy formation.

The new deep field also provides an astronomical gold mine for powerful new ground-based telescopes located in the southernhemisphere to undertake follow-up observations of galaxies and precisely measure their distances.

All of Hubble's new cameras and other instruments were trained on the sky simultaneously for the observation. The SpaceTelescope Imaging Spectrograph was used to dissect light from a quasar (bright, active core of a distant galaxy) in its field ofview. The light from the quasar has traveled nearly three- quarters of the way across the universe, and provides a powerfulthree-dimensional probe of the universe's hidden structure. Invisible clouds of primeval hydrogen gas strung along billions oflight-years between us and the quasar will be detectable in the signature of the quasar's light. The quasar is so brilliant it is like asearchlight shining through haze.

The original HDF engaged hundreds of astronomers around the world. Broad conclusions were drawn based on meticulousfollow-up studies of the myriad galaxies along Hubble's extremely narrow line-of-sight. To date, conclusions about the rate ofstar formation and evolution of galaxy shapes have been based on this one narrow "core-sample" of the universe. Because theoriginal HDF was picked as a seeming bland example of what the universe at large probably looks like, astronomers haveassumed it was a representative sample. But they needed a second sample to validate early assumptions, and they needed a fieldthat contained a distant quasar to give them important additional information that the northern field did not contain.

The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. (AURA)for NASA, under contract with NASA's Goddard Space Flight Center. The Hubble Space Telescope is a project of internationalcooperation between NASA and the European Space Agency.

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