Exploring the Milky Way: Our Galactic Home and Beyond
Written on
Chapter 1: Introduction to the Milky Way
The Milky Way Galaxy serves as our celestial abode, a remarkable stellar landscape that has captivated humanity for eons.
Thousands of years ago, our early human ancestors gazed at the vast, dark sky from the plains of Africa, their imaginations sparked by the twinkling stars. Various cultures crafted myths around the luminous band that stretched across the night. Little did they know, the Milky Way consists of hundreds of billions of stars, part of a broader cosmos containing trillions of galaxies. Later in the program, we will engage with Dr. Joe Pesce, an astrophysicist from the National Science Foundation, who will delve into the supermassive black hole situated at the heart of our galaxy.
Chapter 2: Historical Perspectives on the Milky Way
In 1610, coincidentally the same year Henry Hudson discovered Hudson Bay, astronomer Galileo Galilei aimed his telescope at the Milky Way, marking the first instance of an individual observing distinct stars within this hazy band of light. For centuries, humanity believed that the stars of the Milky Way encapsulated the entirety of the universe. The Andromeda Galaxy, the nearest significant galaxy to our own, can even be seen with the naked eye; it is the farthest object observable without a telescope. For a long time, this blurry patch was thought to be a local nebula filled with gas and dust.
In 1920, The New York Times criticized rocket pioneer Robert Goddard, suggesting he lacked the foundational knowledge taught in schools. Yet, science marched on, culminating in what is known as the Great Debate. This intellectual contest between Harlow Shapley and Heber Curtis addressed the nature of “spiral nebulae” like Andromeda. Shapley maintained that these entities were relatively small and part of the Milky Way, while Curtis argued they were actually island universes akin to our galaxy. Spoiler: Curtis was correct.
Today, we recognize that galaxies vary greatly in size and shape, but a commonality among them is the presence of a supermassive black hole at their core. Sagittarius A* (pronounced Sag A Star), the supermassive black hole located at the center of the Milky Way, boasts a mass exceeding four million times that of our Sun. Recently, astronomers utilizing the Event Horizon Telescope—a global network of radio telescopes—captured the first detailed images of Sagittarius A*.
Chapter 3: The Structure and Future of the Milky Way
Galaxies are broadly categorized into four primary types: spiral, elliptical, irregular, and my personal favorite—peculiar galaxies, which I can relate to. The Milky Way is classified as a barred spiral galaxy, featuring distinctive bars within its spiral arms. We believe our star system resembles the barred spiral galaxy UGC 12158, located nearly 400 million light-years away.
Our stellar family is ancient, having formed over 13.5 billion years ago, making the Milky Way approximately three times older than Earth and the Sun, and nearly as old as the universe itself. Despite its longevity, nothing endures indefinitely. In over four billion years, the Milky Way is predicted to collide with the Andromeda Galaxy—the significant neighbor next door—resulting in a merger to form a new, oddly shaped megagalaxy, humorously dubbed Milkdromeda. Don’t worry; we have billions of years before we have to finalize that name.
Join us next week on The Cosmic Companion for an exploration of Robots in Space! We will be talking with Jason McKenna, the Director of Educational Strategy at VEX Robotics. Be sure to tune in starting June 14.
To catch up on all our episodes, visit TheCosmicCompanion.tv or find us online at The Cosmic Companion. James Maynard, founder and publisher of The Cosmic Companion, has a background in physics, chemistry, and history, and resides in Tucson, Arizona, with his wife, Nicole, and their cat, Max.
Did you enjoy this episode? Subscribe to receive every episode of The Cosmic Companion via email on Medium! You can also support The Cosmic Companion by subscribing to the exceptional writing featured on Medium. Join us on The Cosmic Companion Network for our podcast, weekly video series, informative newsletter, and news briefings on Amazon Alexa, and more!