If Andromeda Were Brighter, This is What You’d See (2014)
waitbutwhy.com
waitbutwhy.com
1. https://www.reddit.com/r/spaceporn/comments/1u0dxs/andromeda...
My reaction on seeing this, probably like that of many other people, was, “wow, that would be so cool”. But of course if it looked like this normally we wouldn’t think much of it at all, just like all the other gorgeous sci-fi skies we see in movies or read about in books: multiple moons, two suns, close proximity to a ringed planet, etc. If these were our sky, they would be unremarkable.
We are surrounded by incredible beauty and so rarely stop to contemplate it. But the beauty is there nonetheless.
Your idea is a great reminder to pause and look up. There are deep lessons in the sky.
The former is physically unlikely although we'd see a very bright core if we lived next to a quasar. But the latter would turn the entire sky into a blaze of stellar glory. Far more stars would be visible, and we'd also see more nebulas between them. And other galaxies.
So the entire sky would be much busier. The Moon would be blindingly bright, the Sun would be unbearable - unless we had HDR eyes and maybe protective membranes for daylight - and Andromeda wouldn't stand out as much among all the other sky candy.
We now know the Milky Way is probably nearly 200,000 light years across[1]. And that it's not only much larger, but much more massive - probably larger than Andromeda[2].
When we talk about these collisions being billions of years away, we're also really only talking about the main portions of the galaxy - all of the globular clusters are going to start interacting way sooner. We're already seeing star formation in the Milky Way's globular clusters as a result of interaction with the Large Magellanic Cloud, even though we're 2.4ish billion years from the primary collision occurring [3].
Last year NASA also came out with a bunch of images on what the night sky will look like as the Andromeda collision occurs: https://kottke.org/19/10/behold-our-dazzling-night-sky-when-...
1. https://www.nbcnews.com/mach/science/milky-way-galaxy-may-be... 2. https://www.businessinsider.com/milky-way-is-much-more-massi... 3. https://www.universetoday.com/144556/an-upcoming-impact-with...
See, if my lifespan is 4.5 billion years, then I can just sit here and wait until Andromeda become a daily light show when it finally got close enough.
Look through a live telescope yourself will give you a very VERY different feeling when compare to look at a picture on NASA website.
I have an amateur telescope, 130EQ. I still remember the feeling it give to me when the first time it brought Saturn into my view, and then again for Jupiter, stars and clusters ...
For me, the best way to get over all the unhappiness, anger and depressions, is to sit down in the pitch dark of the night, setup the telescope and hunting for the stars.
Sadly I managed to broke it's tripod few years back :(
It took forever to get it in frame, and I wasn't even sure what I was looking for until I finally centered it. I knew it was brighter than the other stars and that it was probably a planet but not sure which one it was.
Finally got it in frame and focused, saw the rings and jumped up and down exclaiming "it's Saturn, it's Saturn!". I was super excited and kept having to readjust the telescope because of Earth's rotation as it moved out of frame.
It was great night with my family and they still remember it to this day.
To someone who don't have it before, we're basically looking at a blur dot slightly larger than a peanut. But when you do it yourself, the memory you'll receive is priceless.
I strongly recommend everybody try it out when they have chance.
Well, not quite. It’d be quite static as the merger would take a long time on the scale of a human lifetime.
With the exponential growth rate in technological sophistication, we could, in the forseeable future, have levels of personal safety and medical care that are many orders of magnitude greater than they are now.
If the humans alive today make it to the point where the average life expectancy is pushed to, say, 1000 years, then they stand a decent chance of living to see technology advance to levels that provide extreme (e.g. billions of years) life extension.
If you got a ramscoop engine, maybe you'd be able to grab enough propellant to push you at 1g for years at a time while cleaning your path of particles that'd impact your shielding.
There's been a lot of speculation about scooping up hydrogen from the interstellar medium as fuel, but I think it's mainly wishful thinking.
And while at the speed of light time passes infinitely slow for you, it passes infinitely fast for the universe, which would very abruptly end your exploration.
We will not be exploring any significant portion of our galaxy without rewriting our current theory, inventing a game changing technology, or maybe discovering some phenomena.
The distance from the Milky Way to Andromeda is only about 25 Milky Ways, but the distance from the Sun to Alpha Centauri is about 29 million Suns.
Also 266,900 earth orbits away
Other interpretations of the GP would imply the GP thought 267,000 / 5,000 is about 1.5. I'm pretty sure the GP isn't making that mistake.
That said, I think you might be interestested in the sister post I made to yours.
Or the RL version in Sweden: http://www.swedensolarsystem.se/en/
To quote Douglas Adams, Earth is "Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy". Intersteller distances are much smaller in galactic cores. For example, at the center of Andromeda, the average intersteller distance is 860 AU (compared to 266,900 for Earth-Centauri)[1].
Alternatively, Andomeda huge and on a colision course with the milky way, but not our closest neighbor. Both the Milky Way and Andromoeda have many smaller and closer neighbors, Some of which are of appreciable size. For example, the Large Magellanic Cloud is a "smaler" galaxy with about 30 billion stars and is 170kly or about one milky way diameter away from us.[2]
https://astronomy.com/magazine/ask-astro/2006/01/how-close-c...
Think of all the human history that occurred over 100,000 years — that’s how long it takes for light to go from one side of the Milky Way to another.
The Gaia telescope has helped us revise a lot of numbers around the Milky Way - we're actually likely the biggest kid on the block. The estimate the size of the Milky Way to be 170,000 to 200,000 light years across.
Well, not really. I mean, that doesn't tell me anything about its hugeness, because apparent size is based on a ratio. They're making a ratio with light years on both sides, so they effectively cancel out. 2.5 million / 140,000 is 17.8. So Andromeda is only 17.8 times as far away from us as its diameter. (which is, to me, a very interesting takeaway)
You could substitute "millimeters" for "light years" and it would appear the same size, i.e. a 459 foot diameter object that is 8200 feet away would have the same apparent size as Andromeda.
Not trying to criticize the article, but thought it was an interesting way they put it.
It's more or less obvious that such an object cannot be very close, and thus it's apparent size in our sky really does convey something about its size.
That was my interpretation, at least.
I could imagine ancient people seeing a galaxy that size (if it was bright enough), and guessing it was a few hundred miles away and under a hundred miles across.
This comment is too persnickety to actually be asked in good faith imho.
Of course, there can be plenty of stars outside of that radius, but in a comparatively small number.
You’ve joined people like her grandma and grandpa, a ‘pleese ossifer girl’ who wrote me a speeding ticket and gave her a tattoo, and her paediatrician in the realm of ‘really cool dudes’. In my wildest dreams, one day I’ll become a really cool dude too. :)
Seriously, thank you. You made today’s home daycare really really cool. And you’re infinitely less expensive than the ‘pleese ossifer girl’ so you even get old dad bonus marks.
Edit - If you happen to work in a role where an absolutely glowing thank you letter from a very happy parent would help your career, my email address is in my profile.
My four year old has lost a lot during the pandemic. I like to show her things that I know she will like and space is one of her passions. Unfortunately, she’s four so her questions can go from low level, to profound, to areas where I just don’t have a bloody clue.
You have already really helped me help her. Can I ask for a favour? If you have any links you like, videos you enjoy or films/book recommendations, would you mind sharing them? My kid’s interest in astronomy far exceeds my knowledge and at this point, I don’t even know what questions to ask! :)
Edit - Sorry not to add this originally, but don’t worry about things like age appropriateness or what have you. She’s into lots of things that I’m baffled by, from My Little Pony to astronomy.
https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g/fea...
Their relatively low density and distance from the main portion of the galaxy means that even if you brightened them, they'd largely just look like other stars in the sky and would be hard to distinguish from being part of the general background of stars our galaxy provides, so there wouldn't necessarily be much point in doing so.
https://youtube.com/watch?v=4disyKG7XtU
Most stars and matter will become part of the fused galaxy, "Milkomeda" is one proposed name. Some will be flung int intergallactic space.
The Sun will have entered its white dwarf phase. Earth will either be a cinder, or have been subsumed by or possibly be nova ejecta of the Sun.
So I can only think about interstellar and intergalactic distances relative to this measure, which itself I can't comprehend.