The Milky Way is a barred spiral galaxy, which means that it is a spiral galaxy with a bar-shaped structure that consists of stars. The Milky Way is just one of the several galaxies in the universe. However, it is important for us because it is home to our solar system. You will find it interesting to know that the Earth is situated on one of the arms of our galaxy.
Intriguing Facts about the Milky Way
As seen from the Earth, the Milky Way appears as a hazy band of white light in the sky during the nights. It divides the night sky into two somewhat equal hemispheres.
It is nearly impossible to estimate the exact age of the Milky Way. However, the age of the oldest star in the galaxy is about 13.2 billion years.
Our galaxy is composed of a disk of gas, dust, and stars that surround a bar-shaped region. The disk forms four arm structures that take a spiral shape. The galactic center of the Milky Way is in the direction of Sagittarius. The galactic disk bulges outwards at the galactic center. It has a diameter of a value between 70,000 to 100,000 light years.
The bulge, disk, spiral arms, and the halo can be identified as parts of the Milky Way. The bulge is round in shape and composed of old stars, dust, and gas. It is 10,000 light years wide.
The flattened region surrounding the bulge is the disk. It consists of young stars, gas, and dust. The gas is mainly hydrogen and helium. The dust makes many regions of the disk opaque. It's because of the dust clouds that the center of the galaxy cannot be seen in visible light. The disk has a weak magnetic field which affects the movement of the charged particles in the galaxy and can change the path of or trap cosmic rays. The disk lacks a sharp boundary which is why astronomers believe that there are multiple disks in our galaxy.
Arm-like extensions that begin at the bulge of the Milky Way are called spiral arms. They are named as the Perseus Arm, the Scutum-Crux Arm, the Carina and Sagittarius arm, and the Norma and Cygnus Arm. It has been discovered that there is an outer extension to the Cygnus Arm. The Orion Arm, which is a relatively smaller arm, houses our solar system.
The halo in the galaxy consists of individual old stars and clusters of old stars, as well as dark matter. These clusters are called globular clusters which may be 15 billion years old, and are the oldest components of the Milky Way. The halo is more than 130,000 light years wide.
The largest star in the Milky Way is the Pistol star. It is believed to be 100 times as big as the Sun and 10,000,000 times as bright. It was known to lie in the Pistol nebula in our galaxy.
The ALMA radio telescope detected the presence of a large molecular cloud in the Norma spiral arm of the Milky Way, about 24,000 light years from Earth. Carbon emissions were observed in the center of this cloud. This discovery was of a star in formation, a protostar, which is believed to be one of the brightest stars in the galaxy.
The mass of the Milky Way is estimated to be 5.8x1011 solar masses. Most of its mass is dark matter, a hypothetical matter that is not reactive towards electromagnetic forces. But the existence of dark matter is apparent through the study of the effects of gravity on visible matter.
The Sun is a huge star central to our solar system. It traverses through the space in the Milky Way. The Sun's galactic motion is in the direction of star Vega and is tilted at an angle of 60 sky degrees to the galactic center. The Sun oscillates up and down relative to the galactic plane.
For the solar system to complete one orbit around the galaxy, it takes as many as 225 to 250 million years! This time period is referred to as a galactic year.
These facts and figures pertaining to the Milky Way make us realize the insignificance of our existence in relation to the infinite expanse of the universe.