Have you ever imagined your cosmic address in the Universe? If someone from another galaxy needs to send you mail, the address will look like this. Suppose you live in a village called Bhandari Gram, then your address would be like this– Village: Bhandari Gram, PO: Chatia, District: Biswanath, State: Assam, Country: India, Continent: Asia, Planet: Earth, Solar system, Oort Cloud, Local Interstellar Cloud, Local Cavity, Orion Arm, Milky Way, Local Group, Virgo Supercluster, Laniakea Supercluster, the Universe. Isn’t that exciting? Today we will explore all the names mentioned above hierarchically. Stay tuned to this blog post to discover fascinating things about the Milky Way!
Exploring the Milky Way Step by Step
Before exploring the Milky Way, we need to learn a few concepts and their location in the Universe. However, we will skip the address till your continent & start from planet Earth. Here we go:
- Planet Earth: We all know that we live on planet Earth. It’s a part of the Solar System. There are 8 other sister planets also continuously revolve around the star Sun.
- Solar System: It consist of 9 planets revolving around the star Sun in a cyclical motion. Our planet Earth is a part of the solar system that takes 365 days to revolve around the sun. The other 8 planets of the Solar System are Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. However, Pluto is a dwarf planet and keeps it busy on and off the list of planets.
- Oort Cloud: It is a vast cloud of icy bodies surrounding the Solar System. Dutch astronomer Jan Oort was the person who proposed the idea of icy ghost shell surrounding the Solar System.
- Local Interstellar Cloud (LIC): The LIC is where our Solar System entered 10,000 years ago and is expected to be exited in the next 1,900 years. The LIC has the same temperature as the Sun’s surface.
- Local Cavity: Also known as Local Bubble, it is a region of low-density gas within the interstellar medium. It is located at the Orion Arm of the Milky Way. It is estimated to be spread over an area of 1,000 lightyears.
- Orion Arm: Spanning over 3,500 lightyears, is a minor spiral arm also known as Orion-Cygnus Arm. our Solar System is surrounded by Orion Arm. It is named after Orion Constellation, one of the most prominent constellation of Northern Hemisphere (in winter) and Southern Hemisphere (in summer).
- The Milky Way: The galaxy, where we reside is known as the Milky Way. Our solar system is located within the 13 billion years old galaxy. The Milky Way contains between 100 to 400 billion stars and spread over1,00,00 lightyears, which we will explore in the next paragraph.
- Local Group: The Local Group includes many galaxies, including the Milky Way and Andromeda. It is spread over 10 million lightyears. In 1936, Edwin Hubble introduced the term “Local Group” in his book “The Realm of the Nebulae.”
- Virgo Supercluster: Also known as the Local Supercluster, contains the Virgo Cluster and the Local Group. At least 100 galaxies including our own Milky Way reside within Virgo Supercluster. It spans area of 110 million lightyears. The Virgo Supercluster or Local Supercluster is a component of the larger Laniakea Supercluster, which we will discuss in the next paragraph.
- The Universe: It comprises everything that we call space. Our Solar System, Galaxy, Local Supercluster, everything resides within the Universe. The exact area of the Universe is still unknown. The Sun is one of a few hundred billion stars and the Milky Way is one of the hundred billion galaxies of the Universe. Now you can imagine how vast the Universe is.
I hope you all have known your cosmic address. Now we will discuss the main subject of this blog, the Milky Way. Planet Earth & the Solar System is a part of the Milky Way. It is home to a hundred to four hundred billion stars and the same number of planets. The Galactic Centre is the Milky Way’s barycenter. A barycenter is a dynamic point that refers to the center of mass of two or more bodies that orbit one another. The solar system is situated at a radius of 27,000 lightyears from the Galactic Centre of the Milky Way. Arching the night sky, the Milky Way is a visibly hazy band of white lights. All the stars we see with the naked eye at night are part of the Milky Way. Due to its low surface light, background lights like light pollution & moonlight can highly reduce the Milky Way’s visibility. This makes it difficult to see the Milky Way from suburban areas compared to rural areas.
In 1610 AD, Galileo Galilei used a telescope to study the Milky Way and discovered that it consists of countless stars. In a document written in 1755, the German philosopher Immanuel Kant speculated based on an earlier research by English astronomer Thomas Wright, that the Milky Way is a rotating structure housing a huge number of stars, held together by gravity similar to the planets in the Solar System. For many years, there were controversies regarding the Milky Way’s composition and nature. This debater was settled in the year 1920 by Edwin Hubble at the Mount Wilson observatory, where he used 2.5 meter Hooker telescope. With this telescope, Edwin was able to produce astronomical photographs that allowed him to resolve the outer parts of the spiral nebulae into individual stars. Hubble also identified Cepheid variables, which he used as a benchmark to estimate the distance to these nebulae. Hubble made a landmark discovery when he determined that the Andromeda nebulae is approximately 2,75,000 parsecs away from the Sun, which is far too distant for it to be a part of the Milky Way.
Conclusion
The Milky Way is a vast galaxy that is home to our Solar System along with billions of other stars, planets, and celestial bodies. It is much more than just a smattering of light in the night sky. Gaining knowledge about the Milky Way helps us feel more connected to the immense cosmos of which we are a part. The complexity of space and time is revealed by the Milky Way, from its stunning spiral arms to its dense galactic core. We are not just learning about our past but also our position in the universe as we continue to investigate and analyze our galaxy. The next time you look up into the night sky, remember that you are gazing at your actual location in the universe, a part of a huge galaxy that is both beautiful and mysterious. There are many secrets of the mighty universe still waiting to be discovered. Do you think, there are other universes like the one we live in?
Call to Action
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