Student Lesson Classifying Galaxies Start of Lesson

Home , Dwingeloo 1, NGC 2023, NGC 4027, NGC 4261, NGC 4881

What is a galaxy? A galaxy is made of billions of stars, dust, and gas all held together by gravity. Galaxies are scattered throughout the Universe. They vary greatly in size and shape. Not all galaxies look alike.

This is a galaxy.

http://world.smv.mus.va.us/~hastings/student2.htm (1 of 6) [5/25/1999 12:33:53 PM] Student Lesson

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 observed many differences. In 1926, an astronomer named Edwin Hubble decided to classify the galaxies, grouping them according to some logical scheme. He could have classified them according to color, because galaxies are different colors. You can see many different colored galaxies in the Hubble Deep Field image. He could have classified them according to size, calling small galaxies "dwarf galaxies" and calling large galaxies "massive galaxies". After considering different schemes, he decided to arrange or group them by shapes. He would classify them according to the way they looked. In science, the study of something according to its form or structure is called "morphology".g galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxyLet'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 elliptical refers to its degree of "roundness". Hubble used the letter "E" to stand for elliptical galaxies. To see elliptical galaxies, click on the Galaxy Guide.

http://world.smv.mus.va.us/~hastings/student2.htm (2 of 6) [5/25/1999 12:33:53 PM] Student Lesson

Galaxy Guide by Josh Kennedy

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

To see spiral galaxies, click the Galaxy Guide. galaxy galaxy glalxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxygalaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy galaxy

The third type of galaxy reminded Hubble of a spiral with a solid 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.

http://world.smv.mus.va.us/~hastings/student2.htm (3 of 6) [5/25/1999 12:33:53 PM] Student Lesson

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 type is divided into smaller groups? Click here to review. To show the relationship of the galactic shapes, Edwin Hubble arranged the main types of galaxies and the sub-types into a chart that has come to be called "The Tuning Fork Diagram". The Hubble "Tuning Fork Diagram" is the simplest way to classify galaxies. When you look at a picture of a galaxy, and try to classify it, you are trying to place it on the diagram where it belongs. You have seen some pictures of galaxies in this lesson and have looked at how they were classified. 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 your browser does not work with java applets, Click here.

The Hubble Telescope has looked far into space and discovered many galaxies. Travel to the Hubble Space Telescope Institute to look at an image of a newly discovered galaxy. See if you can classify it by its shape. 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 here when you have finished your visit to Space Telescope Science Institute. Space Telescope Science Institute

The Hubble Space Telescope is making frequent new

http://world.smv.mus.va.us/~hastings/student2.htm (4 of 6) [5/25/1999 12:33:53 PM] Student Lesson discoveries. If you want to do more galaxy exploring at the Hubble Space Telescope Institute, Click Here Use the Back button at the top of your Web Browser to return here when you have finished your visit to Space Telescope 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 Hubble Deep Field Academy. Remember this picture?

This image was taken by the Hubble Space Telescope in December of 1995. It shows lots of previously unknown galaxies of different colors, shapes, and sizes. Use this link to the "Cosmic Classifier" to test your new skill at classifying galaxies in the Hubble Deep Field image. Want to find out more about Edwin Hubble's Classification system? Click on the obsrvatory dome!

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

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

Something mysterious at the heart of an elliptical galaxy!

http://world.smv.mus.va.us/~hastings/student2.htm (5 of 6) [5/25/1999 12:33:53 PM] Student Lesson 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

http://world.smv.mus.va.us/~hastings/student2.htm (6 of 6) [5/25/1999 12:33:53 PM] Edwin Hubble at the 100 inch telescope Classifying Galaxies Edwin Hubble at the 100 inch Telescope Edwin Hubble (1889-1953) guides the exposure of a photographic plate at the Newtonian focus of the 100-inch telescope in 1923. With this telescope, Hubble measured the distances and velocities of galaxies, work which led to today's concept of an expanding Universe. According to this profound idea, the Universe began ten to twenty billion years ago with a Big Bang. The receding galaxies that Hubble observed trace the expansion of space from that dense beginning. The telescope is a mechanical masterpiece and was dedicated as an International Historical Mechanical Engineering Landmark on June 20, 1981, by the American Society of Mechanical 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 taught Spanish and physics as well as coached basketball at New Albany High School, Indiana, in 1914. The New Albany High School Yearbook "Vista" was dedicated to him. Look at the dedication page of the 1914 NAHS yearbook to see a picture of Coach Hubble and the winning basketball team, then use the back arrow at the top of your browser to return here. For more information about Edwin Hubble and his system of galaxy classification Click Here, then use the back arrow at the top of your browser to return here.

This page last updated December 12, 1997 Return to lesson

http://world.smv.mus.va.us/~hastings/edwin1.htm [5/25/1999 12:34:03 PM] Elliptical Galaxies 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 deal with this variation, Hubble divided the "E" classification into 8 sub-groups, which he called "E0", "E1", "E2", "E3", "E4", "E5", "E6", and "E7". E0 galaxies are nearly circular in shape. E1 galaxies are stretched out a little. E2 galaxies are more elongated, E3 galaxies even more elongated or flattened, all the way up to E7 galaxies, which are extremely elongated or stretched out. Look at these examples:"E1", "E2", "E3", "E4", "E5".

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http://world.smv.mus.va.us/~hastings/elipmain.htm [5/25/1999 12:34:07 PM] Spiral Galaxies Classifying Galaxies Spiral Galaxies When you looked at elliptical galaxies you saw that as the classification numbers progressed from E1 toward E7, their appearance was more and more flattened or elongated. Edwin Hubble observed other galaxies that were elongated, but they were different from elliptical galaxies because they had bright centers. He called the bright centers of galaxies "nuclei". He noted that many galaxies with bright nuclei also had "arms" spiraling out from the middle. He called these galaxies 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 tightly the 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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http://world.smv.mus.va.us/~hastings/sprlmain.htm [5/25/1999 12:34:11 PM] Barred Spiral Galaxies Classifying Galaxies Barred Spirals

In about a third of spiral galaxies, the arms spiral out, not from the center, but from a straight 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 increasing openness 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 the Day" 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

http://world.smv.mus.va.us/~hastings/bsmain.htm [5/25/1999 12:34:22 PM] Irregular Galaxies Irregular Galaxies Large Magellenic Cloud courtesy David Malin (© Anglo-Australian Telescope Board). Galaxies that can't be classified as either spiral or elliptical are called irregular galaxies. Every irregular galaxy is unique. It doesn't look like any other galaxy. It just isn't a spiral or an elliptical. Irr I galaxies have lots of young stars, gas, and dust, but do not have spiral arms. Irr II galaxies look strange. It seems likely that Irr II galaxies have been distorted by collisions with other galxies at some time in their history. South of the Equator, it is possible to see the Large and Small Magellanic Clouds, the two irregular galaxies closest to our own Milkey Way Galaxy. Astronomers predict that they will eventually collide with the Milkey Way and be incorporated into our own galaxy.

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Page last updated April 3, 1998

http://www.smv.mus.va.us/~hastings/irreg.htm [5/25/1999 12:34:41 PM] Hubble Tuning Fork Diagram Classifying Galaxies Hubble Tuning Fork Diagram

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

BACK

http://world.smv.mus.va.us/~hastings/tunfork.htm [5/25/1999 12:34:47 PM] Instructions for Classification Test 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 would have 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 to place the galaxy images on the Hubble Tuning Fork Diagram. To move the galaxy pictures onto the Hubble 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 you wish to move it again, you can follow the same directions. When you have finished placing all the galaxy images on the diagram, check your work by clicking on the the Galaxy Guy. Start Here: Classifying galaxies Page last updated on May 29, 1997

http://world.smv.mus.va.us/~hastings/direct.htm [5/25/1999 12:34:59 PM] Classification Check 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

http://world.smv.mus.va.us/~hastings/check.htm [5/25/1999 12:35:12 PM] Dwingeloo 1 Discovery of a Nearby Spiral Galaxy Behind the Milky Way

R.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. Summary

The disk of the Milky Way contains a lot of gas and dust, which obscures about 20% of the extragalactic sky. Galaxies hidden behind the Milky Way may have an important influence on the dynamics of the Local Group and its peculiar motion relative to the cosmic microwave background radiation. Here we report the discovery of a large spiral galaxy, which we call Dwingeloo 1, during the course of a search for 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 a subsequent optical image suggests that it is of type SBb. The detection of Dwingeloo 1 early in the course of this survey suggests that many more galaxies hidden behind the Milky Way remain to be discovered. Harry Ferguson [email protected]

http://icarus.stsci.edu/~ferguson/research/dogs/dogs.html [5/25/1999 12:35:19 PM] HST Imagesby Subject

Hubble SpaceTelescope Images 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 System

■ Venus ■ Mars ■ Jupiter and its satellites ■ Saturn, its rings and satellites ■ Uranus, its rings and satellites ■ Neptune ■ Pluto/Charon ■ Comets

http://oposite.stsci.edu/pubinfo/subject.html (1 of 13) [5/25/1999 12:35:30 PM] HST Imagesby Subject ■ Asteroids (Minor Planets) ■ Other

Venus

■ Venus in Ultraviolet Light Mars

■ Colossal 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 satellites

■ Hubble 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

http://oposite.stsci.edu/pubinfo/subject.html (2 of 13) [5/25/1999 12:35:30 PM] HST Imagesby Subject ■ Comet/Jupiter Encounter ■ Jupiter and Io Saturn, its rings and satellites

■ Telescope 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 satellites

■ Huge 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 is Warming Up (STScI-PR98-23) ■ Hubble Watches Uranus ■ Color image of Uranus ■ Uranus: Rings, Satellites and Clouds Neptune

■ Hubble Helps Find Evidence that Neptune’s Largest Moon is Warming Up (STScI-PR98-23 June 24, 1998) ■ Hubble Provides A Moving Look At Neptune's Stormy Disposition (STScI-PR98-34) ■ Hubble Makes Movie Of Neptune's Rotation And Weather ■ New Neptune Clouds ■ Neptune

http://oposite.stsci.edu/pubinfo/subject.html (3 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject Pluto and Charon

■ Surface of Pluto ■ Pluto and Charon Comets

■ Comet 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 Objects

■ Hubble Shoots the Moon ■ Leonid Meteor Storm ■ Kuiper Belt Comets ■ Gas Cloud Around the Sun

Stars

■ Vast 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

http://oposite.stsci.edu/pubinfo/subject.html (4 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject ■ 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 the Most Massive ■ 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

Nebulae

■ Multiple 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

http://oposite.stsci.edu/pubinfo/subject.html (5 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject ■ 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 the Most Massive ■ 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 Clusters

■ Nearby 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

http://oposite.stsci.edu/pubinfo/subject.html (6 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject ■ Star Birth in NGC 1850

Novae and Supernovae

■ SN1987A 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 Evolution

■ Vast 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

http://oposite.stsci.edu/pubinfo/subject.html (7 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject ■ Star Birth in M16 ■ "Proplyds'' in Orion Nebula

Nearby Galaxies

■ Ring 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

http://oposite.stsci.edu/pubinfo/subject.html (8 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject ■ Gas Disk in Active Galaxy M87 ■ Supernova 1987A Rings ■ Supernova in Galaxy M51 ■ Galaxy M100

Distant Galaxies

■ 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) ■ 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) ■ Hubble Finds Most Of Visible Light In The Universe ■ World's Most Powerful Telescopes Team Up With A Lens In Nature To Discover Farthest Galaxy In The Universe ■ 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

http://oposite.stsci.edu/pubinfo/subject.html (9 of 13) [5/25/1999 12:35:31 PM] HST Imagesby Subject ■ Quasar PKS 2349 ■ QSO 1229+204

Cosmology (The Universe)

■ Hubble Completes Eight-Year Effort to Measure Expanding Universe (STScI-PR99-19) ■ 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) ■ 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 Discover Farthest Galaxy In The Universe ■ 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

http://oposite.stsci.edu/pubinfo/subject.html (10 of 13) [5/25/1999 12:35:32 PM] HST Imagesby Subject Catalog Numbers

■ Hubble 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

Messier

■ M57 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 NGC

■ NGC 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

http://oposite.stsci.edu/pubinfo/subject.html (11 of 13) [5/25/1999 12:35:32 PM] HST Imagesby Subject ■ 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) ■ 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 Clusters

■ A2218 Gravitational Lens in Galaxy Cluster Abell 2218 Herbig-Haro Objects

■ Stellar Jets and Disks PKS Radio Galaxies

■ HST Observes Radio Galaxies ■ Quasar PKS 2349 Gliese Stars

■ Brown Dwarf Gliese 229B ■ Low-Mass Companion to Gl105a ■ Inside Red Dwarfs (Gl752b) ■ Small Star (Gl623b)

General

❍ Maryland 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

http://oposite.stsci.edu/pubinfo/subject.html (12 of 13) [5/25/1999 12:35:32 PM] HST Imagesby Subject

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❍ Most Recent Public Images ❍ 1999 Releases ❍ 1998 Releases ❍ 1997 Releases ❍ 1996 Releases ❍ 1995 Releases ❍ 1994 Releases ❍ First 1994 Post-Servicing Images ❍ Pre-Servicing Mission Images

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❍ About these Images ❍ Text of Press Releases ❍ Additional Background Text ❍ Animations ❍ Public Outreach Home Page ❍ Space Telescope Science Institute

color_rule.gif (369 bytes) The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, 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 the European Space Agency (ESA). Office of Public Outreach -- [email protected]

http://oposite.stsci.edu/pubinfo/subject.html (13 of 13) [5/25/1999 12:35:32 PM] Amazing Space Web-Based Activities

Educator wanted for Academic Year 1999-2000 The Space Telescope Science Institute's Office of Public Outreach is seeking a full time teacher from any academic level, grades 6-12, to participate in their Internship Program. The intern will be actively involved in the development of interactive activities for the World Wide Web; as well as, conducting pilot programs to encourage partnerships and distribution of materials nationwide.

Amazing Space is a set of web-based activities primarily designed for classroom use, but made available for all to enjoy. Current activities include:

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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 Telescope through 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.

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http://amazing-space.stsci.edu/ (2 of 2) [5/25/1999 12:35:49 PM] The Online Planetarium Show: The Life of Hubble The Life of Edwin Hubble

(1889 - 1953)

Edwin Hubble was an American astronomer who made vital contributions to the study of galaxies, establishing the existence of galaxies outside of the Milky Way and proving that the universe is expanding. For his revolutionary contributions to our understanding of galaxies and of the scope of the universe, Hubble was recognized by the astronomical community in 1983, thirty years after his death, when the Space Telescope 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 both his parents and his grandparents. At a young age, Hubble had a taste for books and an interest in astronomy, 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 to work hard nonetheless to pay the balance of his expenses. Perhaps his most interesting job during this time was as a lab assistant to Robert Millikan -- well known for determining the charge of an electron in his Nobel prize-winning oil drop experiment. Hubble received his B.S. degree from the University of Chicago and was offered a Rhodes Scholarship to study law at Queens College in Oxford. Though Hubble started a law practice after returning to the United 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 in an observatory. From the time he began his doctorate work at the University of Chicago's Yerkes Observatory in 1914 to his death, Hubble worked with many observatories and was influential in the construction 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 the Mount Wilson Observatory with its 100-inch telescope. Above all, his research there demonstrated the need 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 his research. Mount Palomar. Most of Hubble's work was done at the Mount Wilson Observatory, but he was intimately involved with the Mount Palomar Observatory, part of the committee that oversaw its

http://tqd.advanced.org/3461/hubble_i.htm (1 of 3) [5/25/1999 12:35:53 PM] The Online Planetarium Show: The Life of Hubble construction. Even more importantly, he advised and assisted in the construction of the Mount Palomar 200-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 in the field of astronomy over great clusters of stars, called "nebulae." At the time, there was no evidence that 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 years than 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 away from the earth. In fact, he concluded that these star systems are each "island universes," not part of our own galaxy. This was an enormously important discovery, for it opened up a great new realm of research and 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 looking at the wavelengths of their light. If the wavelengths are longer and towards the red end of the spectrum, then the galaxy is going away from us; but if the wavelengths are shorter and bluish, then the galaxy is coming towards us. Later in 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 these galaxies were moving away from Earth.

Diagram. Red shift and Blue shift. Hubble used the wavelengths of light to determine whether galaxies were moving towards or away from us. Galaxies with wavelengths in the red regions are moving away while those with wavelengths in the 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 away more quickly than those closer to us. The very notion that these galaxies were actually receding is an important one because it is a central tenant of the Big Bang theory, in which a powerful explosion initiates 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-reaching discoveries. Hubble grouped galaxies into three main categories:

http://tqd.advanced.org/3461/hubble_i.htm (2 of 3) [5/25/1999 12:35:53 PM] The Online Planetarium Show: The Life of Hubble ● 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 we regularly use these terms to describe galaxies and though this terminology is exceedingly important to astronomy, 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 instrument for astronomical purposes. For all of Edwin Hubble's incredible discoveries that are discussed in this biography -- particularly his proof of the very existence of galaxies outside of the Milky Way -- it would seem that the leaps in astronomy's understanding of the universe made by his work are comparable to those made by the studies Galileo or Copernicus. Yet for all of his accomplishments, Hubble's name is relatively obscure; even when we hear about the Space Telescope that was named in his honor, we rarely learn about his contributions or life. According to several biographers, he should be looked upon as an astronomer who "revolutionized" our understanding of the universe -- much like Galileo or Copernicus. Perhaps in several hundred years we will.

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http://tqd.advanced.org/3461/hubble_i.htm (3 of 3) [5/25/1999 12:35:53 PM] Galaxy Hot Links to other Astronomy Resources 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 general interest regarding the Hubble Space Telescope (HST) and the Space Telescope Science Institute (ST ScI). This includes information or interest to educators, students, the media and the general public; pictures resulting from observations by HST 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 a NASA-sponsored partnership of museums, researchers and educators. SEG-way is the public user interface of the Science Information Infrastructure (SII), funded by NASA's Information Infrastructure

http://world.smv.mus.va.us/~hastings/links.htm (1 of 4) [5/25/1999 12:36:33 PM] Galaxy Hot Links to other Astronomy Resources Technology and Applications (IITA), a component of the Federal High Performance Computing and Communications program (HPCC). What is a galaxy? - To continue your study of galaxies, visit this site. It is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC) at the NASA Goddard Space Flight Center in Maryland.

StarChild: A learning center for young astronomers a COOL site for kids, includes Level I and Level 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 world wide web. Many of them have more information about galaxies.

Students for the Exploration and Development of Space - Internet Space Archive LPL/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 at SEDS (Students for the Exploration & Development of Space). It contains open and globular star clusters, 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 the Internet allowing students to interact with scientists and engineers while they work. A project of the National Aeronautics and Space Administration (NASA), IITA is working on all of this and more by funding 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 galaxies contains 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 and charged particles that exist in each galaxy. If you are interested in background information about types of galaxies, or the origin of the radiation, links will give you this information at a high school or undergraduate 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

http://world.smv.mus.va.us/~hastings/links.htm (2 of 4) [5/25/1999 12:36:33 PM] Galaxy Hot Links to other Astronomy Resources What's New Curriculum materials and on-line courses. Newsletters and magazines, Images and Animations, 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 nearby galaxies or distant galaxies

Space Hotlist at NASA.

Lots of space links

STAR HUSTLER Home Page