Credit: NASA, H. Ford(JHU), G. Illingworth(UCSC/LO), M. Clampin(STScI), G. Hartig(STScI), the ACS Science Team and ESA Structure of the Universe I 宇宙的結構 I

Credit: Watanabe Tsuyoshi

Credit: Space Imaging Uluru 世界中心 3.6 km Ayres Rock 艾爾斯岩

Credit: NASA Goddard Space Flight Center km

Credit: JHU/NASA 30 Earth Earth 地球 Moon 月球 km In scale

Credit: Claire C Smith Earth 地球 Sun 太陽 k m 1 Astronomical Unit (AU) 天文單位 8 light minutes 光分

Credit: Addison Wesley 1 AU 50 AU 6.8 light hours 光時

Credit: KAGAYA Kuipler Belt 凱伯帶 ~ AU Kuiper belt objects (KBOs)

Oort Cloud 奧爾特雲 50,000 to 100,000 AU

Credit: Akira Fujii Milky Way 銀河 Crux 南十字座 α Cet 半人馬 α Rigel Kentaurus 南門二 Proxima Centauri 比鄰星 4.22 light years 光年

Credit: NASA/JPL-Caltech/R. Hurt (SSC) The Milky Way Galaxy 銀河系

Credit: NASA/JPL-Caltech/R. Hurt (SSC) The Milky Way Galaxy 銀河系 light years 400 billion stars Spiral arms 旋臂

Credit: Pearson Prentice Hall, Inc.

Galactic Environment in 10 light years Credit: P. C. Frisch, University of Chicago

Credit: Linda Huff

Credit: NASA/JPL-Caltech/W. Reach (SSC/Caltech) 恆星際空間 Interstellar Medium (ISM) Ions 離子 Atoms 原子 Molecules 分子 Dust grains 塵粒 Electromagnetic radiation 電磁波 Cosmic rays 宇宙射線 Magnetic fields 磁場 99% gas; 1% dust 90% H; 10% He IC 1396

N44 Credit: European Southern Observatory 恆星際空間 Interstellar Medium (ISM) Component Fractional Volume Temperature (K) Density (atoms/cm³) State Molecular clouds< 1 % hydrogen molecules Cold Neutral Medium (CNM)1-5% neutral hydrogen atoms Warm Neutral Medium (WNM)10-20% neutral hydrogen atoms Warm Ionized Medium (WIM)20-50% ionized hydrogen H II regions~10% ionized hydrogen Coronal gas, Hot Ionized Medium (HIM) 30-70% highly ionized (both hydrogen and trace metals)

NGC1999 Credit: NASA and The Hubble Heritage Team (STScI) Nebula 星雲

Credit: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA M17 Omega Nebula 奧米加星雲 Nebula 星雲 Gas 氣體 Dust 塵埃 Interstellar Clouds 星際雲

Credit: NASA/JPL-Caltech/E. Churchwell (University of Wisconsin-Madison) Interstellar Cloud 星際雲 Molecular Cloud 分子雲 － H 2 H I Region － H H II Region － H +

Credit: NASA, The Hubble Heritage Team (AURA/STScI) Keyhole Nebula 鑰匙孔星雲 Molecular Cloud - Star Birth

M16 Eagle Nebula 鷹狀星雲 Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) H II Region - Stellar Nursery 星際育嬰室

Credit: NASA and The Hubble Heritage Team (STScI/AURA) IC4406 Retina Nebula 視網膜星雲 Planetary Nebula 行星狀星雲

Ring Nebula 戒指星雲 Credit: NASA/JPL-Caltech/J. Hora (Harvard-Smithsonian CfA)

Credit: Anglo-Australian Observatory/ Royal Observatory Edinburgh Vela Supernova Remnant 船帆座超新星殘骸 Supernova Remnant 超新星殘骸

C34 Veil Nebula (West) 面紗星雲 ( 西段 ) Credit: N.A.Sharp, REU program/NOAO/AURA/NSF

Credit: Linda Huff Galactic Environment in 1500 light years

Credit: National Geographic

Credit: Axel Mellinger All Sky - Optical

Credit: Jerry Lodriguss Milky Way 銀河

Credit: N.A. Sharp, REU Program/NOAO/AURA/NSF M7 Ptolemy's Cluster 托勒密星團 Star Cluster 星團 Open Cluster 疏散星團 Young stars

The Pleiades 七姊妹星團 Credit: Matthew T. Russell

Credit: Russell Croman NGC1435 Merope Nebula 昴宿五星雲 Reflection Nebula 反射星雲

NGC 3603 Credit: Wolfgang Brandner (JPL/IPAC), Eva K. Grebel (Univ. Washington), You-Hua Chu(UNiv,. Illonis Urbana-Champaign), NASA

Credit: Russell Croman M13 Hercules Great Globular Cluster 武仙座球狀星團 Globular Cluster 球狀星團 1,000,000 Stars Old Stars

M80 Credit: NASA and the Hubble Heritage Team (AURA/STScI)

Credit: NASA/JPL-Caltech/S. Stolovy (SSC/Caltech)

Credit: Farhad Yusef-Zadeh et al., VLA, NRAO Galactic Center Radio Arc

Credit: NASA/CXC/MIT/UCLA/UMass/D.Wang, F.K.Baganoff, M.Muno

Credit: NASA/CXC/MIT/F.K.Baganoff et al. Sagittarius A* 人馬座 A* 3,000,000 Solar Mass

Credit: CXC/A. Hobart Supermassive Black Holes 特大質量黑洞