14: The Milky Way Galaxy
- Page ID
- 64064
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)“See yonder, lo, the Galaxyë
Which men clepeth the Milky Wey,
For hit is shyt. ”
Geoffrey Chaucer
The House of Fame, Circa 1380
Upon completion of this module, the student will be able to:Upon completion of this module, the student will be able to:
- Identify the characteristics of the Milky Way Galaxy
- Identify the contributors to our understanding of the Milky Way Galaxy
This module presents an overview of our home galaxy, the Milky Way Galaxy, its characteristics, satellite galaxies, and how it compares to other galaxies.
- 14.1: What do you think?
- This page examines how ancient civilizations revered the heavens and questions whether modern people would do the same if they experienced clear night skies devoid of light pollution. It invites exploration of the reasons behind the worship of celestial objects, suggesting that contemporary beliefs and values are likely different from those of ancient cultures.
- 14.2: The Milky Way — Our Home Galaxy
- This page discusses the Milky Way Galaxy, estimated to have 100 billion to 400 billion stars, classified as a barred spiral galaxy. Its vastness is hard to verify from within. Initially, astronomers misidentified galaxies as “nebulae.” The Milky Way is part of the Local Group and Virgo supercluster, resembling NGC 6744 with its dust lanes, spiral arms, and central bar, often described as a 'picture postcard' representation of itself.
- 14.3: Milky Way Galaxy Satellites
- This page discusses the Milky Way Galaxy, highlighting its two main satellite galaxies, the Large and Small Magellanic Clouds, and at least ten dwarf galaxy satellites, with the possibility of hundreds more. The Milky Way measures about 100,000 light-years in diameter and 1,000 light-years thick, appearing as a thin disc. Observing the galaxy is challenging due to the Interstellar Medium, but methods like radio astronomy and infrared observation aid in understanding its structure and components.
- 14.4: Milky Way Galaxy Research
- This page discusses the historical understanding of the Milky Way Galaxy, beginning with Aristotle's theory of atmospheric ignition and contrasting views from his contemporaries. It highlights Persian astronomer Abū al-Rayhān al-Bīrūnī's suggestion that the Milky Way consists of numerous star-like fragments. Additionally, it features a photograph of the Milky Way from Yosemite Valley, showcasing the galaxy's dust lanes.
- 14.5: Galileo Galilei, First to See the Milky Way Galaxy
- This page discusses Galileo's 1610 observations of the Milky Way Galaxy through a telescope, revealing numerous stars that were previously unseen. His work, "Sidereus Nuncius," documented these findings and represented a major leap in astronomy, demonstrating the power of telescopic technology to enhance our understanding of the universe.
- 14.6: The Milky Way Galaxy’s Shape
- This page discusses the historical understanding of the Milky Way Galaxy, starting with Immanuel Kant's 1755 proposal that it is a gravity-bound collection of stars, influenced by Thomas Wright. It then mentions William Herschel's 1785 sketch of the Milky Way's shape, derived from his star counts, which suggested that the Solar System is near the galaxy's center.
- 14.7: Andromeda Galaxy
- This page outlines significant astronomical observations and theories regarding the Milky Way and neighboring galaxies. Heber Curtis's 1917 discovery of a nova in Andromeda led to the identification of galaxies, corroborated by Edwin Hubble. Harlow Shapley advanced our understanding of the Solar System's position and the Milky Way's size but overlooked Hubble's spiral galaxy insights.
- 14.8: X-Ray and Gamma-Ray of the Milky Way Galaxy
- This page presents findings from 2010 when the Fermi Gamma-ray Space Telescope observed two large high-energy emission bubbles near the Milky Way's core, each about 25,000 light years across. Furthermore, a 2014 estimate by Ray Villard indicated that the galaxy hosts around 100 billion planets, averaging one planet per star among the estimated 100 billion stars in the Milky Way.
- 14.9: Earth’s Position within the Milky Way Galaxy
- This page explains that the Solar System's location is advantageous for observing space, as it is free from dense dust of the Interstellar Medium and not too close to the Milky Way's center, which would expose it to constant daylight and harmful radiation from Sagittarius A*, the supermassive black hole.
- 14.10: A Spinning Spiral
- This page discusses the differential rotation of the Milky Way Galaxy, noting that the Solar System takes 230 million years to orbit it. It highlights the approaching Andromeda Galaxy, which may collide with the Milky Way in 3 to 4 billion years, eventually merging into an elliptical galaxy over a billion years. Additionally, it reflects on themes of curiosity and exploration inspired by Edgar Allan Poe.