Although it may be one of the closest galaxies to our own, since the Andromeda Galaxy is 2.5 million light years distant it would take 2.5 million years to get there if (and it's a huge 'if') we could travel at the speed of light.
To reach M31, the Andromeda galaxy, in a human lifetime would require a velocity of 0.99999 c. Behind the relativistic spacecraft on Earth, millions of years would have passed, but the same crew that departed would reach their destination.
The technology required to travel between galaxies is far beyond humanity's present capabilities, and currently only the subject of speculation, hypothesis, and science fiction. However, theoretically speaking, there is nothing to conclusively indicate that intergalactic travel is impossible.
In the Andromeda galaxy, it is generally accepted that humans originated from the Core World of Coruscant, but they have been found present as the dominant species on relatively unknown planets such as Ahch-To and Reylea, though the latter are more imbued with special properties than the rest of the galaxy.
If Andromeda was standing still, it would take roughly 4,000 earth years for every 1 light year, at current propulsion speeds. That means we can traverse the 2.5 million light years in 1x10^10 years or about 10 billion years (give or take).
Accordingly, the galactic “accident” will occur in about 3-4 billion years. This event will have catastrophic consequences for both: The Milky Way and Andromeda will first be torn apart by the gravitational interaction, and then merge into one huge Milkomeda galaxy with a bright core.
For most space objects, we use light-years to describe their distance. A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!
Andromeda–Milky Way collision
The merger will totally alter the night sky over Earth but will likely leave the solar system unharmed, according to NASA.
Can the Andromeda Galaxy support life? Since we can't yet say for certain whether there are any other stars in our own galaxy that host life, it is even harder to say whether there might be life, or at least the conditions for life, in another galaxy.
According to the research, the halo of both the Milky Way and the Andromeda galaxy have started touching each other. The halo of a galaxy is essentially a large layer of gasses, space dust and outlier stars that surrounds a galaxy. These halos determine the true extent of a galaxy.
So, while Earth will eventually leave the solar system one way or another, it's not something we will have to worry about for a few billion years yet.
The trite answer is that both space and time were created at the big bang about 14 billion years ago, so there is nothing beyond the universe. However, much of the universe exists beyond the observable universe, which is maybe about 90 billion light years across.
So, to leave our Galaxy, we would have to travel about 500 light-years vertically, or about 25,000 light-years away from the galactic centre. We'd need to go much further to escape the 'halo' of diffuse gas, old stars and globular clusters that surrounds the Milky Way's stellar disk.
In August 2012, Voyager 1 became the first spacecraft to cross into interstellar space. However, if we define our solar system as the Sun and everything that primarily orbits the Sun, Voyager 1 will remain within the confines of the solar system until it emerges from the Oort cloud in another 14,000 to 28,000 years.
While Voyager 1 lacks the velocity necessary to escape the Milky Way galaxy, it doesn't actually need to. Because the Milky Way galaxy itself will collide and begin to merge with the Andromeda galaxy within about 4.5 billion years. It's unlikely any objects within either galaxy will collide with something in the other.
If you could view the full extent of the Andromeda Galaxy, it would appear shockingly large in the sky. The galaxy's disk appears as a fuzzy smudge about one-quarter of a degree wide (about half the width of the full Moon) to the naked eye, and just slightly larger through binoculars.
The black hole was hidden within the star cluster B023-G078, in the Andromeda galaxy. It was originally thought to be a cluster of stars, but researchers now believe it is a stripped nucleus - a remnant of small galaxies that fell into bigger ones and had their outer stars stripped away by gravitational forces.
It is estimated that there are roughly 200 billion galaxies (2×1011) in the observable universe. Most galaxies are 1,000 to 100,000 parsecs in diameter (approximately 3,000 to 300,000 light years) and are separated by distances on the order of millions of parsecs (or megaparsecs).
Our Milky Way is on a collision course with another spiral galaxy called Andromeda. Today Andromeda is visible as a speck of light in the night sky, but about 5 billion years from now, it will be tangled up with us. Our galaxy's spiral arms will disappear, and so will our supermassive black hole.
So the short answer is 0 < P < 1. Andromeda is around 2–3 times more populous in terms of star composition - It contains upwards of 1 trillion stars, compared to the to 200–400 billion stars within the Milky Way. There's a possibility for several million Earth like planets each with the potential to harbour life.
When you're wondering what happens when two galaxies collide, try not to think of objects smashing into each other or violent crashes. Instead, as galaxies collide, new stars are formed as gasses combine, both galaxies lose their shape, and the two galaxies create a new supergalaxy that is elliptical.
The scale of a human is less than 1/5,000,000 the scale of Earth, but Earth is just a proverbial drop in the cosmic ocean, with a diameter of only a little over 10,000 kilometers.
1 Light Year in Days
As defined by the International Astronomical units (IAU), A light year is the distance traveled by light in a vacuum in one Julian year is equal to 365.25 days. Therefore, one light - year = 365.25 days.
Constant Speed
So what does this sentence really mean? Surprisingly, the answer has nothing to do with the actual speed of light, which is 300,000 kilometers per second (186,000 miles per second) through the "vacuum" of empty space.