In this article, we will explore the Milky Way and galaxies, and how they differ from each other. Join us for a detailed discussion.
What is the Milky Way?
The Milky Way is a galaxy in which our Solar System is located. It appears in the sky as a faint band of light stretching from the constellation Cassiopeia in the north to the constellation Crux in the south. The Milky Way is brighter towards the constellation Sagittarius, which is the center of the galaxy. A noteworthy fact is that the Milky Way divides the sky into two approximately equal parts, indicating that the Solar System is very close to the plane of this galaxy.
The Milky Way.
The Milky Way is a barred spiral galaxy classified as SBbc according to the Hubble classification (this type of galaxy is disk-shaped with loosely connected arms and a prominent bulge near the center) with a mass approximately 10^12 times that of the Sun (M☉), containing about 200-400 billion stars (not counting faint stars). The Milky Way has a diameter of about 100,000 light-years. The distance from the Sun to the center of the Milky Way is approximately 27,700 light-years.
The term “Milky Way” refers specifically to the galaxy that contains our Solar System. The Milky Way is a spiral galaxy with a diameter of approximately 100,000 to 120,000 light-years, containing around 100 to 400 billion stars.
Like many other galaxies, the Milky Way also harbors a supermassive black hole at its center known as Sagittarius A*.
What is a Galaxy?
Spiral Galaxy.
A galaxy is a large system of celestial bodies and matter bound together by gravitational forces, including stars, stellar remnants, interstellar medium containing gas, cosmic dust, and dark matter, an important yet poorly understood component.
Classification of Galaxies
Andromeda Galaxy.
Galaxies are primarily classified into three main morphological types: elliptical, spiral, and irregular. Additionally, a more detailed description of galaxy structures based on their shapes is provided in Hubble’s classification scheme.
- Elliptical Galaxies: Hubble’s classification evaluates elliptical galaxies based on their elliptical shapes, ranging from E0, which are nearly spherical galaxies, to E7, which are elongated. These galaxies resemble ellipsoids, appearing elliptical when viewed from an angle. This morphology displays very few structural characteristics and generally contains relatively little interstellar matter.
- Spiral Galaxies: These galaxies have stars arranged in a spiral pattern towards the center. Although stars and most other visible matter in this type of galaxy lie on a plane, the majority of the mass in spiral galaxies is concentrated in a spherical region of dark matter that envelops the visible matter.
- Irregular Galaxies: These galaxies have unusual structures due to tidal interactions with other galaxies.
Dwarf Galaxies
While many galaxies stand out with spiral or elliptical structures, the majority of galaxies in the universe are quite small. These dwarf galaxies are relatively tiny compared to some other galaxies; for instance, they may have a diameter one percent that of the Milky Way and contain only a few billion stars.
