The Site is in Under construction
Our Galaxy
Well, you must have known about the solar system. it has one sun, eight planets, moons, asteroids, comets etc and our earth is also part of this solar system on which you and we live, so this whole solar system is a very small part of the Milky Way Galaxy. So now you must have understood that the Solar System is much bigger than the earth and the Galaxy is much bigger than the Solar System. Galaxies are a huge collection of gases, dust, planets, black holes, moons, comets, dark matter, stars and all of them in the galaxy are connected to each other through gravity. There are about 100 billion to 400 billion stars in this Milky Way and it also has the possibility of having about 50 billion planets. Our Solar System is situated in the outer region of the Milky Way and is revolving around its center. It takes about 22.5 to 25,00,00,000 years to complete one revolution. That means a long time. By the way, how many galaxies are there in the universe? This question must have come in your mind, then you may be surprised to know that there are so many galaxies in the universe that we cannot even count them.
Long ago it was believed that only the Milky Way Galaxy exists in the Universe, but in the 18th century Philosopher Immunal Kant told that the Milky Way is not the only Galaxy in the Universe, but many such galaxies exist. The Hubble Space Telescope observed a small patch of space for 12 days and detected 10,000 galaxies. These Galaxy are of different sizes, colors and shapes. Some scientists also believe that the total number of galaxies in space is so high that their number can be 100 billion, that is, very high. By the way, all this is fine, but why is our galaxy called Milky Way? Interesting question and the answer is that our galaxy is named Milky Way from the Greek. The Romans named this galaxy which means Road of Milk. The Romans called our Galaxy Road of Milk because this galaxy looks like a patch of milk in the sky when viewed from the night side. Now you must be wondering why this galaxy looks white and bright like milk? So the reason for this is that there are billions of stars in our galaxy, that is, there are many stars whose light combined together creates such a sight that white and bright light is visible when viewed from Earth at night. That is why the Galaxy is called the Milky Way Galaxy.
So let's go ahead and talk about what happens in the center of the Galaxy. A black hole is found in the center of most galaxies and a black hole is also present in the center of our Galaxy Milky Way. Black hole is the place where no rule of physics affects because its gravity is very strong. If the light enters the black hole, then it cannot come out, because the black hole absorbs all the light flying towards it. By the way, after knowing this interesting thing lets talk about how many types of galaxies are there, Galaxies are found in many shapes. That's why astronomers divide them into three basic classes.
​
The very first Spiral Galaxies: Spiral Galaxy consists of three visible parts. Disc, bulge and halo. Disc stars are made of gas and dust. The central bulge contains older stars and the spherical halo contains older stars and massive star clusters. Our Galaxy also fall under the Spiral Galaxy. This type of galaxy has curved arms, due to which this galaxy looks like a spin wheel.
In the second type are elliptical galaxies: Elliptical galaxies are smooth and round shaped galaxies. Because the orbits of the stars present in these galaxies are oriented in every direction. They contain little gas and dust and young stars are not present in them. In this galaxy globular, star clusters and dark matter are found around it.
The third is Irregular Galaxy. There are many such galaxies which are neither oval nor spiral, so such galaxies are called Irregular Galaxies.
So after knowing the types, now the next question is, do galaxies collide with each other too? Because there are so many of them, yes, sometimes it also happens that the galaxy comes very close to each other and there is a collision between them. The name of the closest galaxy to our Milky Way Galaxy is Andromeda and when these two galaxies collide with each other, both these galaxies can be destroyed, but at the moment we do not need to worry because at least Nothing like this is going to happen till Five Billionaires. So every now and then you hear that the world is going to end or something like this is going to happen, then just chill.
Elements of our Galaxy
Galaxy dust: The space between the starts is filled with gas and tiny pieces of solid particles or dust. Most of this gas and dust result from the death of starts which either exploded or blew off their outer layers, returning their material to space. From this material, new stars are born. Mostly, this gas and dust can be detected using infrared light.
​
Spiral arms: This Milky Way has spiral arms coming out of its central bulge. These arems are made up of young, bright, blue starts and older, white stars as well as dust and gas. There are stars that lie between these spiral arms; however, they are not as bright. These stars slowly orbit the central bulge following their own path. They take several hundred millions years to complete their orbit.
Image Illustrating Spiral Arms
Star Nursery: Stars are formed within clouds of hydrogen gas. A part of the cloud then forms a dense ball of gas. More gas is attracted because of gravity, thereby compressing the ball into a tighter and hotter mass. As a result, a nuclear fusion is triggered, which converts hydrogen into hellium and radiates energy as a very bright star.
Hot blue star: Stars get their color depending on their temperature. The coolest stars appear red, while the hottest ones are blue. For a star, its temperature is determind by its mass. Blue stars have at least three times the mass of the Sun or even more. Interestingly whether a star has 10 times the mass of the Sun or 150 solar masses, it appears blue to our eyes.
Image Illustrating Stars display different colors in space based on their temperature and mass.
Solar System: Our solar system was formed about 4.6 billions years ago. it includes the eight planets and their natural satelites, dwarf planets such as Pluto and Ceres, asteroids, comets and Meteoroids. The Sun contains almost all the mass present in the solar system and exerts a tremendous gravitational pull on the celestial bodies.
Central Bulge: A Galaxy contains stars, gas and dust. In a spiral galaxy such as the Milky Way, the stars, gas and dust are organised into a "bulge" and "disc", containing "spiral arms" and a "halo". The bulge is a round structure primarily made of old stars, gas and dust. The outer parts of the bulge are difficult to distinguish from the halo. The bulge of the Milky Way is roughly 10000 light year across.
Black hole: Black holes are huge but surprisingly cover only small region. Because of their mass, they have an extremely powerful gravitational force. Mothing can escape them; even light is trapped by a black hole. Black holes have three layers: the outer and inner event horizon, and the singularity. The event horizon of a black hole is the boundry around the mouth of the black hole, where light loses its ability to escape. The Singularity lies at the centre of the black hole. it is a one-dimensional point that contains infinite mass in a considerably small space.
Image Illustrating Massive Black Hole in Orion Nebula
Dark Matter: Dark matter is a kind of matter that cannot be seen using telescopes. However, it accounts for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effect on visible matter, radiation and large-scale structure of the universe. Dark matter accounts for 23 per cent of the universe.
Active Galaxies
From a normal galaxy, most of the light is emmited from the stars that are evenly distributed throughout the galaxy. However, there are some galaxies that emit intense light from their nuclei (the centre). If these same galaxies are viewed in the X-ray, ultraviolet, Infrared and radio wavelengths, they seem to be giving off significant amounts of energy from their nucleus. Such galxies are called active galaxies. They represent a very small percentage of all galaxies. There are four main types of active galaxies, which are given as follows
Radio Galaxy: A radio galaxy serves as a strong source of electromegnetic radiation or radio waves. Their discovery provides proof that the universe can expand, contradicting the steady state theory, suggetsing that the universe would remain steady. Compared to ordinary galaxies, a radio galaxy emits as much as a thousand to a million times more energy per unit time. The giant elliptical galaxy M87 in the Virgo cluster is an example of a nearby radio galaxy.
Quasar: Quasars are the farthest objects that can be seen from our galaxy, and are extremely bright masses of energy and light. Quasar is shorrt for "quasi-stellar radio source" or "quasi-steller object". They are the brightest objects in our universe, although when seen through a telescope they do not appear that bright. This is because quasars are extremely far away. They emit radio waves, X-rays and light waves. They appear as faint red stars to us. Some are belived to produce 10-100 times more energy than our entire galaxy and is only as big as our solar system.
Blazar: A blazar is a dense energy source fuelled by supermassive black holes. They are considered to be one of the most dangerous phenomena in space. These extragalactic objects were first seen and discovered around 1972, because of the technology of "A Very Long Baseline Interferometry". The name was coined by astronomer Ed Spiegel in 1978. They are usually divided into two, the BL Lacertae objects (BL Lac) and optically Violent variable (OVV) quasars. There are also a few intermediate blazers, which have the properties of both the BL Lac and the OVV. They emit high-energy plasma jets as quick as the speed of light. They are a type of compact quasars. They are characterised by their high speed and energy. They are also extremely powerful.
Image Illustrating The power of a quasar originates from supermassive black holes
Seyfert galaxy: Almost all Seyfert galaxies are spiral galaxies and are named after the American astronomer Carl Seyfert, who identified them in 1943. They are among the most intensively studied objects in astronomy because they are thought to be nearby low-luminosity versions of the same phenomenon as observed in quasars. They have cores that emit as much energy at wavelength as the total radiation output of our own Mily Way. However, they do not contain well-defined radio lobes. A striking feature of these galaxies is that their luminosity can change rapidly. In the constellation Pegasus, NGC7742 is known to be a Seyfert galaxy. it is about 72 million light years away. it resembles a fried egg with a very bright nucleus that is visible all wavelengths. it is ringed by blue-tinte stars forming regions and faintly visible spiral arms. The yolk - its yellow centre is about 3000 light years across.
Colliding Galaxies
Several galaxies are members of a group or a cluster. As groups and clusters contain many galaxies that are close together, galaxies tend to collide with each other. In fact, the Milky Way galaxy is colliding with the Sagittarius Dwarf galaxy right now. Galaxy collisions are common but stars in each galaxy are so far apart that star collisions are extremely rare. Even if galaxies do not actually collide, they can still cause harm to each other.
When galaxies interact: When two galaxies pass close to each other, the gravity that they exert can cause both of them to bend out of shape. Both crashes and near misses between the galaxies are referred to as "Interactions"
What happens when they collide?
When two galaxies interact, the clouds of gas inside each galaxy may compress. Compressing the clouds can cause them to collapse under their own garavity, transforming them into stars. This process can lead to a burst of star formation in the interacting galaxies. A new generation of stars may form in a galaxy where the normal star formation may have stopped long ago. Galaxy collision takes place over hundreds of millions of years, so we cannot see them occur. The various types of galaxies are given as follow:
Cartwheel galaxy:
The cartwheel galaxy is also known as "ESO 350-40". This galaxy is a lenticular and ring galaxy. it is about 500 million light year away in the constellation of Sculptor. it as an estimated 150000 light year across. it also has a mass of about 2.9-4.8 x 109 solar masses. Scientists have observed that it rotates at 217 km per second. it was discovered in 1941 by a Swiss astronomer Fritz Zwicky. Zwicky considered his discovery to be "one of the most complicated structures awaiting its explanation on the basis of steller dynamics". it is slightly larger than the Milky Way.
Black Eye galaxy:
The Black Eye galaxy, also known as Messier 64 (M64), Evil Eye galaxy or Sleeping Beauty galaxy, is a famous spiral galaxy that is located in the constellation Coma Berenices. it lies at a distance of 24 million light years from Earth. It is known for the enormous light-absorbing dust band in front of its central region, which has earned the galaxy the names "black eye" or "evil eye". Because of the dust band, the stars in the galaxy's bright core are blurry. This galaxy is a popular target for amateur astronomers because its bright nucleus can be observed even through aa small telescope. Messier 64 is also notable for being composed of two counter-rotating discs, almost equal in mass. The inner disc contains spectacular dust clouds and lanes. All the stars in this galaxy rotate in the same direction as the gas in M64's core region i.e. clockwise, while the gas in the outer regions rotates in an anti clockwise direction.
Mice galaxies:
These galaxies which are also known as NGC 4676, are a pair of interacting galaxies that are located around 300 million light years away towards the constelletion Coma Berenices. These galaxies get their name because the long streams of stars, gas and dust thrown off of each other as a result of their interaction resemble the tails of a pair of mice. These galaxies will eventually merge to form a single galaxy. The tails are the remains of their spiral arms.
ARP 272:
ARP 272 is a pair of colliding galaxies, which consist of two spiral galaxies NGC 6050 and IC 1179. it is around 450 million light years from Earth in the constelletion Hercules. The galaxies are a part of the Hercules Cluster, which is a part of the Great Wall - one of the largest known structures in our universe. The two galaxies in ARP 272 are in physical contact through their spiral arms.
 |  |  |
|---|---|---|
 |  |  |
Antennae galaxies:
The Antennae Galaxies, also known as NGC 4038/NGC 4039 are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starbust phase. Here the collision of couds of gas and dust, with knotted magnetic fields, causes rapid star formation. They were discovered in 1785 by William Herschel. These galaxies are locked in a fatal embrace. Once normal, calm spiral galaxies like the Milky Way, the pair has spent the past few hundred million years bickering with each other. This clash is so fierce that stars have been ripped from their host galaxies to form a streaming arc between the two. In wide-field images of these galaxies, the reason behind their name is clarified - far-flung stars and sreamers of gas stretch into space, which create long tidal tails suggestive of antennae. These two galaxies are known as the Antennae Galaxies because the two long tails of the stars, gas and dust ejected from them due to the collision resemble an insects antennae. The nuclei of these two galaxies will eventually join to become one giant galaxy.
UGC 8335:
UGC 8335 is an interacting pair of spiral galaxies that resembles two ice skaters. it is located in the constellation of Ursa Major, the Great Bear, around 400 million light years from Earth. The interaction has united the galaxies through a bridge of material and has pulled together two curved tails of gas and stars from the outer parts of their bodies. Both galaxies show dust lanes in their centres. It ranks 238th in the Arp's Atlas of Peculiar Galaxies.