Touch the Universe: A Nasa Braille Book of Astronomy

Touch the Universe A NASA Braille B o o k o f Astronom y

b y N o r e e n G r ice

The Joseph Henry Press 500 Fifth Street, NW Washington, DC 20001

Joseph Henry Press • 500 Fifth Street, NW • Washington, DC 20001 The Joseph Henry Press, an imprint of the National Academ ies Press, w a s c r e a t e d w i t h t h e g o a l o f m a k i n g b o o k s o n s c i e n c e , t e c h n o l o g y, a n d h e a l t h m o re widely available to professionals and the public. Joseph Henry was one of the early founders of the National Academ y o f S c i e n c e s a n d a l e a d e r in early A m e r ican science. Any opinions, findings, conclusions, or recomm e n d a t i o n s e x p r e s s e d in this volume are those of the author and do not necessarily reflect the v iew s o f t h e N a t i o n a l A c a d e m y o f Sciences or its affiliated institutions. Library of Congress Cataloging-in-Publication Data G rice, Noreen. To u c h t h e u n i v e r s e : a N A S A B r a i l l e b o o k o f a s t r o n o m y / b y N o r e e n G rice. p.cm . C a p t ions also in Braille; im a g e s e m b o s s e d to be perceivable to the v ision im p a ired. I S B N 0 - 3 0 9 - 0 8 3 3 2 - X ( p b k . : a lk. paper) 1 . A s t r o n o m y — P ictorial works. 2. Braille books— S p e c i m e n s . I. Title. QB68.G75 2002 520’.22’2— d c 2 1 2002010769 C o p y r i g h t © 2 0 0 2 b y N o r e e n G r i c e . A l l rights reserved. P rinted in the United States of Am e rica by the Reese Press, Baltim o re, M a ryland.

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Table of Contents

D e d i c a t i o n a n d A c k n o w l e d g m e n ts . . . . . . . . . . . v A b o u t the A u thor . . . . . . . . . . . . . . . . . . . . . . . . vii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 T h e H u b b l e S p a c e Te l e s c o p e . . . . . . . . . . . . . . 3 T h e H u b b l e S p a c e Te lescope (illustration) . . . . 5 H S T o rbits Earth . . . . . . . . . . . . . . . . . . . . . . . . 7 H S T o rbits Earth (illustration) . . . . . . . . . . . . . . 9 Jupiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Jupiter (illustration) . . . . . . . . . . . . . . . . . . . . . 1 3 S a turn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 S a turn (illustration) . . . . . . . . . . . . . . . . . . . . . 1 7 U ranus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 U r a n u s ( illustration) . . . . . . . . . . . . . . . . . . . . . 2 1 T h e R i n g N e b u la . . . . . . . . . . . . . . . . . . . . . . . 2 3 T h e R i n g N e b u la (illustration) . . . . . . . . . . . . . 2 5 The Hourglass Nebula . . . . . . . . . . . . . . . . . . . 27 T h e H o u rglass Nebula (illustration) . . . . . . . . . 2 9 NGC 2392—The Eskimo Nebula . . . . . . . . . . 31

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N G C 2 3 9 2 — T h e E s k imo Nebula (illustration) E ta C a rinae . . . . . . . . . . . . . . . . . . . . . . . . . . E ta C a rinae (illustration) . . . . . . . . . . . . . . . . G a s e o u s P illars i n M 1 6 — T h e E a g le N e b u la . G a s e o u s P illars i n M 1 6 — T h e E a g le N e b u la (illustration) . . . . . . . . . . . . . . . . . . . . . . . . . G lobular Cluster NG C 6 0 9 3 . . . . . . . . . . . . . G lobular Cluster NG C 6 0 9 3 ( illustration) . . . . G a laxy NGC 4603 . . . . . . . . . . . . . . . . . . . . . G a l a x y N G C 4 6 0 3 ( illustration) . . . . . . . . . . . G a l a x y C luster Abell 2 2 1 8 . . . . . . . . . . . . . . . G a l a x y C luster Abell 2 2 1 8 ( illustration) . . . . . H u b b le N o rthern D e e p F ield . . . . . . . . . . . . . H u b b le N o rthern D e e p F ield (illustration) . . . Final Thoughts . . . . . . . . . . . . . . . . . . . . . . . .

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D E D ICATION T h e s p a c e p r o g r a m is bringing our universe into focus. This book is dedicated to science enthusiasts of all visual abilities - enjoy!

ACKNOWLEDGMENTS T h e ideas that led to the creation of Touch the Universe: A NASA Braille Book of Astronomy, w e r e d e v e l o p e d j o i n t l y b y N o r e e n G r i c e a n d D r. B e r n h a r d B e c k - W i n c h a t z ( D e P a u l U n iversity), who gratefully a c k n o w ledge fundi n g b y N A S A’s H u b b le S p a c e Te l e s c o p e C y c l e 9 E d u c a t i o n a n d P u b lic O u treach G rant. The tactile illustrations were created by N o r e e n G rice w ith evaluation by Benning W e n tworth, Disney’s 2001 Te a c h e r o f t h e Year, and his students at the Colorado School for the Deaf and B lind.

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T h e text w a s c h e c k e d for scientific accuracy by Dr. B e c k - W i n c h a t z a n d D r. D e n n is D a w s o n ( W e s t e r n C o n n e c ticut S tate University). T h a n k s t o S h i r l e y K e ller and Irm a G o ldberg, of C reative Adaptations for Learning, who e n thusiastically assisted the author with the design a n d p roduction of the prototype tactile illustrations, a n d to Pauline Gobeil for assistance with the design of the cover illustration. S p e c ial thanks to Steve M a r a n a n d R a y V illa r d o f N A S A , S k i p B a r k e r, t h e J o s e p h H e n r y P r e s s , R e e s e P r e s s , a n d N a t i o n a l Braille Press for their unique collaboration during the final production phase, and to the astronom e r s w h o a llo w e d their celestial images to be part of this book.

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ABOUT THE AUTHOR N o r e e n G r i c e h o l d s a B a c h e lor of A r t s d e g r e e in A s tronom y f r o m B o s t o n U n i v e r s i t y, a M a s ter of S c ience degree in A s tronom y from S a n D iego State U n iversity, a P rofessional Certificate in M u s e u m S tudies from Tufts University, a n d a C e r t ificate in Nonprofit M a n a g e m e n t t h r o u g h t h e B o s t o n C e n t e r for Adult Education. She has taught astronom y courses for students of all ages, from g ram m a r s c h o o l t h r o u g h c o lle g e , a n d h a s w o r k e d in the planetarium fie ld since 1984. Her first book on astronom y, Touch the Stars , is a Braille/print edition using tactile illustrations.

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INTRODUCTION T h e u n iverse exi s t e d l o n g b e f o r e t h e d a y y o u w e r e b o rn! In fact, astronom e rs believe that it is billions of years old. W h a t you m a y n o t k n o w is that our u n d e r s t a n d i n g o f t h e u n iverse has com e a b o u t only fairly recently. T h o u s a n d s o f y e a r s a g o , a n c ient sky w a tchers o b s e r v e d t h e o b jects of the night sky. T h e y s a w tiny stars, “w a n d e r ing” stars (w h i c h w e c a l l planets), and the changing moon. F o u r hundred years ago, telescopes were first p o inted at the night sky, b ringing into view distant stars that w e r e n o t v i s ible to the unaided eye. M o o n s w e r e s e e n o r b iting Jupiter, a n d c r a t e r s w e r e s e e n o n o u r o w n m o o n . Larger telescopes allow e d observers to glim p s e fuzzy patches of light; som e w e re large groups of stars, som e w e re rem n a n ts of stars’ d e a ths, and others were “citie s o f stars” called g a laxies.

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T h e largest telescopes on Earth are located on m o u n taintops, far from c ity lights and high above m a n y o f the Earth’s cloud layers. H o w e v e r, Earthb a s e d t e l e s c o p e s s u ffer from the haze of the Earth’s atm o s p h e r e a n d a r e a t t h e m e r c y o f c h a n g e a b l e w e a ther patterns. N A S A’s H u b b l e S p a c e Te l e s c o p e d o e s n ’t have these problems; it orbits the Earth a b o v e t h e c l o u d s a n d t h e a t m o s p h e r e a n d is able to s e e c e lestial objects w ith incredible clarity. It is w ith t h e H u b b le S p a c e Te l e s c o p e t h a t w e b e g i n o u r v o y a g e o f d iscovery, starting at Earth and m o v ing to t h e e d g e o f o u r u n d e r s t a n d ing. Prepare to be a s t o n i s h e d a s y o u t o u c h t h e u n iverse! N o te: The Saturn, N G C 4 6 0 3 , a n d A b e ll 2 2 1 8 tactile illustrations m u s t b e v i e w e d h o r izontally. Please turn t h e b o o k c lockwise so that the binding is at the top.

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F igure 1. THE HUBBLE SPACE TELESCOPE T h e H u b b l e S p a c e Te l e s c o p e ( H S T ) w a s n a m e d after the A m e rican astronom e r E d w in H u b b le. It is 4 3 .5 feet (13.1 m e ters) long and 14 feet (4.27 m e ters) w ide. The telescope w e i g h s 2 5 , 5 0 0 p o u n d s (11,000 kilogram s ) . T h e H S T w a s c o n s t r u c t e d o n E a r t h a n d d e p loyed into space by the space shuttle in 1990. Two solar p a n e ls, one on either side of the telescope, provide p o w e r for the telescope’s equipm e n t. A s tro n o m e rs o n E a r t h c o n t r o l the telescope. Im a g e s a r e r e layed b y s a t e llite s d o w n to the control center in Baltim o re, M a ryland.

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F i g u r e 1 s h o w s t h e H u b b l e S p a c e Te l e s c o p e in space. The solar panels have a checkered texture. T h e t e l e s c o p e a n d s o lar panels are raised by a tactile outline.

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Figure 2. HST ORBITS EARTH T h e H S T o r b its a b o u t 3 7 0 m ile s ( 6 0 0 k m ) above the Earth’s surface. Because it is above the Earth, it d o e s n o t h a v e t o s e e t h r o u g h t h e h a z e o f t h e E a r t h ’s atm o s p h e r e . H u b b le is not affected by clouds, rain, o r o t h e r t y p e s o f b a d o b s e r v i n g c o n d itio n s c a u s e d b y E a r t h ’s atm o s p h e r e . W ith its c l e a r v i e w o f s p a c e , t h e H S T h a s p r o v i d e d s o m e o f the m o s t am a z ing views of distant celestial o b jects. From n e ighboring planets, to the birth and d e a th of stars, to groups of stars and galaxies b e y o n d t h e M ilk y W a y, H u b b le is helping us to better u n d e r s t a n d o b jects of our universe and our place w ithin it.

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F i g u r e 2 d e p icts the HST orbiting the Earth. The Earth’s edge (lim b ) i s s h o w n a s a b r o k e n c u r v e . T h e b o rder of A frica is show n b y a d o tte d lin e . This image also appears on the cover of this book.

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Figure 3. JUPITER Jupiter is the largest planet in our solar system . It h a s a d i a m e ter over eleven tim e s that of Earth. O v e r o n e t h o u s a n d E a r t h s c o u ld fit inside Jupiter! T h is giant planet orbits the sun five tim e s farther out than Earth. It takes about tw e lve years for Jupiter to c o m p lete one trip around the sun. Jupiter is a gas planet, m a d e m o s tly of hydrogen, h e liu m , am m o n ia, and m e thane. To t h e n a k e d e y e , i t a p p e a rs as a bright white star. T h r o u g h a t e l e s c o p e , it reveals stripes called bands. The planet rotates o n c e i n a b o u t 1 0 h o u r s a n d t h is m a k e s the planet v e r y w indy. A s t h e b a n d s m o v e p a s t e a c h o t h e r, th e y w h irl a r o u n d c ircular storm s .

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Jupiter boasts the largest storm in the solar system . It is called the Great Red Spot and has been observed for hundreds of years. T h is photograph of Jupiter w a s t a k e n b y R i t a B e e b e ( N e w M e x ico State U n iversity) and Am y S i m o n ( C o r n e ll U n iversity) w ith t h e H S T i n F e b r u a r y 1 9 9 5 . F i g u r e 3 s h o w s t h e o u t l ine of Jupiter. T h e b a n d s a r e displayed as tactile lines that cross the planet. The b r o k e n c u r v e d l ines indicate different currents in the b a n d s o f g a s . T h e G reat R e d S p o t is r a i s e d a long w ith a few s m a ller storm s ( s h o w n a s h o llo w c ircles).

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F igure 4. SATURN S a turn, the sixth planet from the sun, is often called the “ringed planet.” It is not the only planet with rin g s , but it does have the m o s t num e r o u s a n d s p e c t a c u lar rings. The rings are m a d e o f ice and s m a ll rocks. S a turn is the second largest gas-giant planet in our solar system . It h a s a d iameter of alm o s t n i n e a n d a h a lf tim e s that of Earth. Saturn orbits the sun at a distance that is m o r e t h a n n ine and a half tim e s the distance betw e e n t h e E a r t h a n d s u n . To t h e n a k e d e y e , S a t u r n a p p e a r s a s a d im yellow star; but when s e e n t h r o u g h a s m a ll b a c k y a r d t e lescope, Saturn a p p e a rs as a disk with elongations that resem b le e a rs!

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F igure 4 is an im a g e o f Saturn that was taken with the HST in January 1998 by E. Karkoschka (University of Arizona). D iffe r e n t s h a d e s o f b l u e indicate variations of cloud p a rticle s i z e s a n d c h e m ical com p o s itio n s . G r e e n a n d y e llo w indicate haze. The diffe rent colors are represented by tactile stripes across the planet. The rin g s a r e s h o w n w ith a b u m p y texture.

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F igure 5. URANUS U r a n u s is the seventh planet from the sun. It is about half the size of Saturn and orbits t h e s u n a t o v e r n ineteen tim e s t h e d i s t a n c e b e t w e e n t h e E a r t h a n d s u n . T h e p l a n e t c o m p letes one full orbit around t h e s u n e v e r y e ighty-four years. U r a n u s is a “tipped” planet because its poles s o m e tim e s face directly tow a rd the sun. M a n y astronom e r s b e lie v e t h a t U r a n u s w a s tip p e d o n its s i d e w h e n a n o t h e r o b ject collided w ith it b illio n s o f years ago. U r a n u s is not visible with the naked eye. Through a large telescope, the planet appears as a blue-green disk.

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F igure 5 is an im a g e o f U r a n u s t h a t w a s c a p t u r e d b y E . K a r k o s c h k a ( U n iversity of A rizona) u s i n g t h e H S T in A u g u s t 1998. A b right ring is visible and the planet a p p e a r s t o a l s o h a v e a f e w f a inter rings. Blue and green colors indicate clear layers of the atm o s p h e r e . Yello w indicates reflective layers and orange/red colors are the highest layers of the atm o s p h e r e . The b o u n d a r ies betw e e n the different colors are represented with raised lines across the planet. The brightest ring is shown with a dotted tactile line. B a s e d o n o b s e r v a t ions of Uranus, astronom e rs b e lieve that som e c louds orbit this gas planet at s p e e d s g r e a t e r t h a n 3 0 0 m ile s ( 4 8 0 k ilo m e ters) per hour!

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F igure 6. THE RING NEBULA W e n o w l e a v e o u r s o lar system a n d travel tow a rd a c o n s t e llation called Lyra. W ithin this star pattern is a planetary nebula called the Ring Nebula. This cloud is the rem a ins of a star, near the end of its life, w h ich i s s h e d d i n g its o u ter layers. Early astronom e rs using t e l e s c o p e s o b s e r v e d s u c h “ p lanet-shaped” clouds in s p a c e a n d n a m e d them p lanetary nebulae, but they are not really related to planets. T h e R i n g N e b u la resem b les a “sm o k e r ing” in s p a c e . T h e d y ing star is visible in the center. A telescope is required to see the Ring Nebula.

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T h e H u b b le Heritage Te a m u s e d t h e H S T to im a g e t h e R i n g N e b u l a i n O c t o b e r 1 9 9 8 , a s s e e n i n F igure 6 . T h e t r u e c o lors in this im a g e indicate different layers of gases: helium (blue), oxygen (green), and nitrogen (red). The outline of the outer layer of cool nitrogen is represented by a dotted texture, the m iddle hot layer w ith o x y g e n h a s a t e x t u r e o f p a r a lle l lin e s , a n d t h e v e r y h o t c e n t e r a r e a o f h e liu m , with a star, has no texture.

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F igure 7. THE HOURGLASS NEBULA T h e H o u rglass Nebula is a planetary nebula located about 8,000 li g h t y e a r s a w a y, m e a n ing that its light takes 8,000 years to reach Earth. A dying star in the c e n t e r o f t h e n e b u la is ejecting gaseous m a terial into space. The first astronom e rs to view this collection of star debris through a telescope thought it resem b l e d t h e s h a p e o f a n h o u r g lass, so they g a v e it that nam e . T h is January 1996 picture, taken by R . S a h a i a n d J . Trauger of the Jet Propulsion Laboratory, re v e a ls the n e b u la’s detailed wispy structure and a pair of intersecting elliptical rings at the center.

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In this photograph, different colors are used to represent layers of gases: nitrogen (red), hydrogen ( g r e e n ) , a n d o x y g e n ( b l u e ) . T h e d y ing star is seen in t h e c e n t e r. T h e c u r v e d h o u r g l a s s - s h a p e d g a s e o u s structure is raised as curved solid lines and incom p lete lines.

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F igure 8. NGC 2392 - THE ESKIMO NEBULA A s a s tar’ s g a s e s u n d e r g o n u c lear reactions, they are converted from low e r m a s s e lem e n t s i n t o h i g h e r mass ones. When a star can no longer create new elem e n ts, it b e c o m e s u n s table. A b o u t 1 0 , 0 0 0 y e a r s a g o , a s u n - like star in the c o n s t e llation of G e m ini becam e u n s t a b l e a n d b e g a n to fling its gases into space. The gaseous relic of this star is called the Eskim o N e b u l a b e c a u s e it resem b les the shape of a head surrounded by a fur h o o d fro m a w inter coat. The “head” is a bubble of g a s s u r r o u n d i n g t h e d y ing star, and the “fur” is g a s e o u s m a terial m o v ing away from the star. T h e E s k imo Nebula, also called NGC 2392, is visible o n ly w ith a telescope.

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A . Fruchter and the Early Release O b s e rvation ( E R O ) Te a m u s e d t h e H S T i n J a n u a r y 2 0 0 0 t o t a k e this im a g e ( F igure 8) of the Eskim o N e b u la. The n e b u l a ’ s g l o w i n g g a s e s p r o d u c e t h e c o lors used in this im a g e : nitrogen (red), hydrogen (green), oxygen (blue), and helium (violet). T h e “ h e a d ” a n d s u r r o u n d ing gases are raised w ith tactile lines. G a s e s in the “fur” shell are shown as raised curved lines.

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Figure 9. ETA CARINAE Travelin g to the constellation of Carina, w e s e e a star called Eta Carinae, one hundred ti m e s m o r e m a s s ive than our sun. This star becam e v e r y unstable and had a tremendous explosion when, o n e h u n d red fifty years ago, it becam e o n e o f the brightest naked-eye stars in the southern h e m isphere. In Septem b e r 1995, J. M o rse (University of C o lorado) used the HST to image Eta Carinae. Huge “blobs” of gases are seen on each side, m o v i n g a w a y f r o m the center at speeds of 1.5 m illio n m iles (2.5 m illio n k ilo m e ters) per hour. T h e central star, not visible in this im a g e , radiates five m illio n tim e s m o r e p o w e r t h a n o u r s u n !

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In Figure 9, Eta Carinae is shown as a tactile o u tlin e . G a s e s a r e r e p r e s e n t e d b y b r o k e n c u r v e d lines.

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Figure 10. G A S E O U S P ILLARS IN M16 THE EAGLE NEBULA N o t all n e b u lae are the result of dying stars. W ithin t h e c o n s t e llation of Serpens is M 1 6 , also called the E a g le N e b u la. This is an area of gases that r e s e m b l e s t h e s h a p e o f a n e a g l e ’s wing. W e a p p roach the tip of a wing and see pilla r s o f g a s , thousands of li g h t y e a r s a w a y, in space! (A light year is the distance that light travels in one year, about 6 trillio n m iles or 9.5 trillion kilom e ters.) This is the a s t o n ishing discovery m a d e b y J . H e s t e r a n d P. S c o w e n o f Arizona State University, using the H S T, w ith w h ich they captured this im a g e in April 1995. T h e p illar-like structures are actually colum n s o f cool interstellar hydrogen gas and dust that act as incubators for new stars.

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U ltraviolet radiation from n e a r b y s tars is eroding the pillars. Young stars will eventually em e rge from the pillars. F i g u r e 1 0 s h o w s t h e E a g le Nebula pillars with a m ixture of colors that represent different layers of g a s : s u lfu r (red), hydrogen (green), and oxygen (blue). The pillars are outlined by a solid tactile line w ith broken curved lin e s i n s ide representing the m ixing gas layers.

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F igure 11. GLOBULAR CLUSTER NGC 6093 N o w let’s step back from o u r local area of the g a laxy. G a laxies are som e tim e s c a lled “star cities.” A lmost every star visible to the naked eye in our night sky is located within our M ilk y W a y G a laxy. O n the clearest night, far from c ity lig h ts, it is possible to s e e a f e w t h o u s a n d s t a r s , a p p e a r i n g a s p i n p o ints of lig h t against the black night sky. T h e M ilk y W a y c o n t a ins hundreds of billio n s o f stars, so w e a c tually o n l y s e e a h a n d f u l of th e g a laxy’s population. O u r Milky Way Galaxy is called a spiral galaxy b e c a u s e it has spiral arm s i n a p i n w h e e l s h a p e . W e d o n ’t live in the center of the galaxy; we live near a spiral arm , about two thirds of the distance from the c e n t e r.

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S w a rming like bees around the center of our M ilky W a y a r e d e n s e g r o u p s o f s t a r s c a lle d g lobular c lusters. These star clusters contain hundreds of thousands of stars, all b o u n d together by gravity. T h r o u g h a s m a ll telescope, they look like “ s n o w b a lls” of stars w ith bright centers so that the individual stars seem to “blend” together. N G C 6 0 9 3 (also called M 8 0 ) is a g lobular cluster l o c a t e d 2 8 , 0 0 0 lig h t years from E a rth. W h a t w e s e e t o d a y i s h o w t h e g lobular cluster looked 28,000 years ago! T h e H u b b le Heritage Te a m a t N A S A u s e d t h e H S T to capture this im a g e o f N G C 6 0 9 3 in early 1999. The stars in N G C 6 0 9 3 a r e b e lie v e d t o b e s o m e o f the oldest stars in the universe, with ages up to 15 billio n y e a r s . I n F igure 11, the stars are shown as raised dots.

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Figure 12. GALAXY NGC 4603 L e a v ing our M ilk y W a y G a laxy, w e tra v e l to another spiral galaxy called NG C 4 6 0 3 . It lies 108 m illio n lig h t years from u s .

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T h is 1999 im a g e w a s t a k e n b y J . N e w m a n (University of C a lifo r n ia, Berkeley) using the HST. In F igure 12, w e s e e a b r ight galactic center and the spiral arm s o f s t a r s . T h e g a l a x y, w ith s p iral arms, is in tactile outline. Stars are show n a s r a i s e d d o t s a n d b u m p y texture.

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Figure 13. GALAXY CLUSTER ABELL 2218 G a laxies com e in different shapes. O u r M i l k y W a y G a laxy is spiral-shaped. Som e g a l a x i e s h a v e o n ly c ircular or slightly elongated shapes; these are called elliptical galaxies. Som e g a l a x i e s a r e s h a p e d lik e S a turn, with a circular center and elongated s ides; these are called lenticular galaxies. Som e g a laxies look like spirals but have a line of stars (calle d a b a r ) c r o s s ing their centers; these are called b a rre d s p ira l galaxies. Som e g a l a x i e s h a v e n o n s y m m e trical shapes; they are called irregular or p e c u lia r g a laxies. G a laxies are gravitationally bound together in groups. O u r Milky Way is part of the Local Group w h ich, w ith o ther clusters of galaxies, form s the L o c a l Supercluster.

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I n J a n u a r y 2 0 0 0 , A . F r u c h t e r a n d t h e E R O team u s e d t h e H S T t o image a cluster of galaxies called A b e ll 2 2 1 8 , located in the constellation of Draco. T h is galaxy cluster is shown in Figure 13. This group of galaxies lies 2 billion light years from E a rth. The c luster contains spiral, lenticular, a n d e lliptical g a laxies. The spiral galaxies are raised to show the spiral arms, the lenticular galaxies are raised to s h o w e longations, and the ellip tic a l g a laxies are filled circles and elongated circles.

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Figure 14. HUBBLE NORTHERN DEEP FIELD H o w far can our telescopes see into space? In 1995, R . Williams (NASA) and the Hubble Deep Field Te a m u s e d t h e H S T t o i m a g e a n a r e a a b o v e t h e fam o u s B ig D ipper star pattern--an area that a p p e a red devoid of stars. The astronom e r s t o o k 3 0 0 i m a g e s o f t h e s a m e a rea of the sky over a period of 10 days, hoping to see objects four billio n tim e s fainter than the lim it o f hum a n v ision. W h e n the p h o t o g r a p h s w e r e c o m b ined, astronom e rs w e re a s t o n ished to find that they had discovered t h o u s a n d s o f p r e v i o u s l y u n d e t e c t e d g a laxies, lying billio n s o f lig h t y e a r s a w a y ! S o m e o f t h e s e g a laxies are seen in the process of form a tion. The final image is called the Hubble Northern Deep Field (of G a laxies).

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Figure 14 shows the Hubble Northern Deep Field. G a laxies in a variety of shapes are visible and have b e e n r a ised in tactile form . The field of view in this image is tiny, only about 1/30th the diam e ter of the full m o o n . This im a g e s h o w s o n ly 25% o f the entire H u b b le N o rthern D e e p F ield, just a sm a ll s a m p le of the m a n y g a laxies in the view !

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Final Thoughts T h e i m a g e s a n d p h o t o g r a p h s i n t h is book are only a s m a ll sa m p le of the m a n y o u tstanding views taken w ith the H S T. T h e y p r o v i d e s t e p p i n g - s t o n e s o f travel, from E a rth orbit to galaxies billions of light y e a r s a w a y. T h e H u b b l e S p a c e Te l e s c o p e h a s b r o u g h t a s h a r p e r v iew of the night sky. O ther orbiting telescopes and n e w innovative ground-based technologies will continue to expand the limits of our understanding. O n l y a h u n d r e d y e a r s a g o , w e b e g a n t o e x p lore the s ize and structure of our ow n G a laxy. W h o k n o w s w h a t w o n d e r s a w a it us as w e c o n t i n u e o u r v o y a g e of discovery into the universe?

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