Allan:
My older sisters and I once found the Andromeda galaxy just above the constellation Andromeda. We were very excited to see that faint, fuzzy little patch of light that we figured was the whole Andromeda galaxy which is 2.5 million light-years away from our own Milky Way galaxy. We had to look at it with averted vision to actually see it nicely. BUT, we were wrong. We were not looking at the whole Andromeda galaxy.
THAT was only the bright centre of the galaxy we were looking at, bright because the stars are densest in the centre of the galaxy. It has a cute name, the Galactic Bulge.
If your eyes could gather light like a time-lapse camera, and the faintest stars would become much brighter than you could actually see them, the Andromeda galaxy would look like this is the night sky beside the moon. What my sisters and I were actually looking at was the centre, the rest of the galaxy was too dim to be seen.
Can you imagine seeing this sight in the night sky? It’s there, you just can’t see it, the stars are too dim.
Another astonishing thing is that the Andromeda galaxy and our Milky Way galaxy are barrelling toward each other at 250,000 MPH OR 402,336 KPH. In around 4.5 billion years, the two galaxies will collide with each other. Devastating? Not really. The stars in the galaxies are so distant, there will be few if any colliding stars. The galaxies will pass through each other however, gravity will pull them back together and the two galaxies will form a giant, elliptical galaxy.
When the two galaxies collide, the Solar System will be swept out three times farther from the galactic core than its current distance. They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.
However, by that time, our sun would have gone through its red giant stage and would have already consumed Mercury and Venus. Earth will be very close but its water would have been boiled away long ago and Earth will be at that time devoid of all life. A crispy cinder would be all that is left of that majestic, life-filled world.
Hang on to your hats. Our solar system located in the Orion arm of our own Milky Way galaxy which is 100,000 light-years across and swirling around like a giant frisbee, travels at an average speed of 515,000 mph (828,000 km/h). Even at this rapid speed, the solar system would take about 230 million years to travel all the way around the Milky Way. That’s one hell of a merry go round ride!
Above. On a dark night far away from city lights, you can see a part of our own Milky Way galaxy. You are looking toward the centre of our galaxy where stars are the densest.
Our Milky Way Galaxy above shows where our solar system is located.
Okay, one more mind blow. The galaxies Andromeda and the Milky Way are actually now touching. Each galaxy has what is called a Galactic Halo, gas, dust and stray stars. It was discovered that the galactic halo of our galaxy and Andromeda stretch out a lot further than thought.
In other words, it’s the faint halos of the galaxies that indeed appear to have started to touch one another. Thus, in a manner of speaking, the collision between our two galaxies has already started.
Andromeda and our Milky Way are on a collision course.
When the galaxies do meet, it will make for a pretty sight from the earth. On approach, the Andromeda galaxy will warp the band of the Milky Way across our sky. Eventually, the galaxies' cores will merge. However, by then, there will be no one on earth to see this sight.
