NGC 224 - Heaven in Sky - Andromeda Galaxy

 

 NGC 224

When we look up, on a clear moonless night, away from any city lights, we can see thousands of stars glistening above us. But these are only a tiny portion of the stars that make up the Milky Way Galaxy, our galactic home. Beyond what we can see in the night's sky are hundreds of billions of other stars and beyond the Milky Way are billions of other vast galaxies. That bright smudge of light ahead is our sister Galaxy, Andromeda, the closest large Galaxy to ours and the most distant thing most of us humans can see with the unaided eye. From Earth, it is around 2.5 million light-years away, an incredibly vast distance. But luckily, by using this simulation, we can travel faster than the speed of light. We can leave our solar system within a blink of an eye. The planet that every single human has ever existed upon is now just a tiny speck. The Sun, just another star in a sea of bright dots.  

 

To understand the sheer scale of the Milky Way Galaxy, however, we need to travel more than 500 light-years vertically, a journey that will allow us to see our Galactic home in all its glory. The Milky Way is a barred spiral galaxy and is around 13.6 billion years old. Large pivoting arms can be seen stretching out across the cosmos, creating a disk shape that spans an area more than 100,000 light-years. It's incredible to think that our star, the Sun, is just one of an uncountable number of stars that make up this Galaxy. Although it has been estimated to contain between 100 billion and 400 billion stars. As we drift ever further from the Milky Way’s bright glare, look into the distance, and you will see many mysterious glowing dots.

 

These are entire galaxies scattered across the observable universe. You may notice that the galaxies are not scattered randomly, instead, they are grouped in gravitationally bound clusters, interspersed with vast dark voids, giving the universe a magnificent cobweb-like structure. The observable universe contains at least one hundred billion galaxies, but there are possibly trillions, and they come in all kinds of different shapes and sizes. Most of these galaxies are extremely far away, however, and can only be seen with powerful telescopes.  But there are some that are, cosmically speaking, relatively close to the Milky Way, close enough to be part of what's called the local group. This group is a vast cluster of more than 30 galaxies, all within a space of around 10 million light-years or so. The Milky Way is just one of  three large galaxies in the local group, but it's not the largest, that would be the one that we are  currently heading towards the Andromeda Galaxy.

 

The magnificent cosmic structure is named after  the area from which it can be seen in the Earth's sky, the Andromeda constellation, which itself  is named after the Ethiopian princess who, according to Greek mythology, was saved  from certain death by the hero, Perseus. Like the Milky Way, Andromeda is a  barred spiral galaxy with enormous circling arms containing a wealth of gas, dust  and bright stars. Andromeda is significantly bigger than the Milky way, however, spanning  an area more than 200,000 light-years across. It also contains many more stars,  estimated to be around the 1 trillion mark. At its center, within that bright bulge hides  a mysterious supermassive black hole that is estimated to have a diameter of 516 million  miles, which is 830 million kilometers, larger than Jupiter's orbit. It contains enough  mass to equal that of 140 million Suns. Compared to Sagittarius a*, the supermassive black hole at  the center of the Milky Way, which only contains the same amount of mass as 4 million Suns however, it’s not just individual stars that orbit the center of this enormous Galaxy. 

That bright yellowish object just off to the side is called M110 and is one of many satellite galaxies that are gravitationally bound to Andromeda. These less massive galaxies have their own impressive collection of stars, all of which orbit their own center, but the galaxies and everything in them also orbits Andromeda. Like how the moon orbits the Earth, yet the Earth and the moon orbit the Sun. The Andromeda Galaxy is roughly 2.5 million light-years from the Milky Way, but that won't always be the case. Because both are on a collision course that will ultimately alter the structure of each galaxy forever. The galaxies are rushing closer to one another at about 70 miles per second, which is 112 kilometers per second, and it is estimated that the collision will begin in around 4.5 billion years from now. While this collision might seem like it could only end in destruction, galaxy mergers often lead to extreme bursts of star formation, leaving the nights sky awash with bright, new stars. Although unfortunately, humans probably won't be around long enough to see this majestic cosmic show play out. Regardless of what we will miss in the future, one thing we can do right now, is go outside on   a clear night and look up into the sky. Find the constellation of Andromeda, then the Galaxy and marvel at the only thing that we can see with the unaided eye that isn't part of the Milky Way. But that will one day join our galactic home and create a new Galaxy, the Milkomeda Galaxy.