Unpopular opinion time

@Philweasel  
I find it hard to believe it took her over a millennium to find anypony, but then she got two in as many decades.

That or there are “Celestial”/Major alicorns and “Ascended”/Minor ones.
 
Celestia and Luna had parents which passed on their celestial status to them, giving them ethereal manes and immortal lives, alicorn magic and the ability to ascend anyone worthy into a non-immortal and more restricted form that couldn’t ascend or spawn more themselves… until Cadance… but I guess this is what happens when you cross-breed an alicorn with a family of privileged and magic-infused prodigies.
 
Though it would imply that for them to truly retire they’d have to give up their own immortality and probably die as a result… ack. Though this separation sure makes more sense that there being no ascensions during the Thousand Years of Nothing (TM), with some rando pegasus being given a horn for beating one villain a couple years before the pilot takes place.

@Latecomer  
She probably just wasn’t looking as hard until she started planning her retirement. Like, she probably alicornized Cadance and Twilight because she was planning on retiring in the first place :D
 
@Poison Trail  
It could just be that Celestia and Luna are crazy powerful because they’ve had so much time to amass power and learn magic. Twilight didn’t get much of a power boost from becoming an alicorn (if she even got any at all) aside from growing a set of wings, but if she were to live for like 3000 years:  

 
We actually saw her pop a little bit of a Celly-like mane when she gained the power to own Sombra, which also kind of hints at that :D  

@Poison Trail  
Well it depends how likely it is in the first place, isn’t it? I mean, Twilight is obviously a deliberate experiment on Celestia’s part, so Cadance is the only “natural” example, and could well have been the only one in millenia if Celly hadn’t taken it as inspiration.

@Latecomer  
Man, how ballsy would it have been of them to have made Sombra’s origin story be that he was Celestia’s first attempt at making an alicorn? :D

@Badumsquish
 
But then where are the other alicorns? Are they all hiding under a rock somewhere? Cause that sure sounds way more plausible than “Well, Celestia just hadn’t been ascending ponies for…. a thousand years… no biggie!”.
 
Though… now that I remember we do see the Tree of Harmony in it’s initial form having Twilight’s cutie mark, so it’s possible that Celestia saw it a thousand years ago and went “Okay, I’m not gonna ascend anyone until I see someone with that mark on it’s ass”, then when she found her ascended a random pony to serve as her babysitter to groom her into being one too.
 
This then leads into the whole “All of Equestria orbits around Twilight Sparkle” theory. Guhhhhhh

@Poison Trail  
I think you give Celestia too much credit in the process. I should clarify - I think Twilight was an experiment in as much as it was her attempt to copy Cadance’s ascension which took her completely by surprise. (Of course, that would require that she and Luna not having ascended via any similar method.)

I still really dig the idea that Celestia’s method of tutoring Twilight was her overcompensating for her failure with Sunset.

@Poison Trail  
Another way to look at it though is that symbol is the symbol of harmony, which Twilight has as her cutie mark because her talent is harmony itself. Like, Celestia and Luna have a sun and moon cutie mark because their talent revolves around the sun and moon; not because the sun and moon are Celestia and Luna shaped :D

I honestly believe Celestia realised Cadance would be important to restoring the Crystal Empire and alicorned her as a possible resource. Twilight similarly, Celestia realised that she was close to harmony and so arranged for Cadance to be her babysitter and tried to tutor her towards becoming the forth alicorn.
 
Celestia’s basically trying to establish a dynasty.

@Badumsquish  
Yeah - I figure star marks are pretty common as representations of magic, and even that one has appeared now and again through the ages.

@Dustcan
 
…Who? ;)
 
@Badumsquish
 
Way I like to think of it, alicorns grow stronger as they get older.
 
No matter what the exact headcanon is, I think it’s essentially inevitable for Twilight to surpass Star Swirl in terms of power, if she hasn’t already done it by blocking Sombra’s attacks successfully. (We don’t know how those two unicorns compare though)

@AC97  
I think she’s past him in raw power (being an alicorn helps)… BUT he has a long lifetime of experience… BUT she has access to over a millenium of magical learning he lacks. So it’s close.

@Latecomer  
Here’s my theory. Twilight’s cutie mark represents three things: power, harmony, and friendship. The purple is power, the white is harmony, the small stars are friendship. Power and harmony are more or less the same size since she values them more or less equally, and they are in the center of the small stars since she uses power and harmony for the sake of friendship:  

 
The Tree of Harmony has only the purple and white star because it only understands power and harmony. Power is smaller and in the center of the much larger harmony since it uses power for the sake of harmony, with no concern or understanding for friendship:  

 
Finally, Mean Twilight has a corrupted all purple-star surrounded by smaller stars. She knows and values only power,  
and she uses her “friends” to obtain it :D  

@Latecomer
 

 
But still, being anywhere near the level of power that one of the greatest wizards that’s ever lived has attained when you’re presumably in your early 20s is not an accomplishment to scoff at, because as you said, she’s way less experienced, for one thing.
 
As for Twilight’s former protege, ironically enough, I like to think she’s around five years older than her, which doing as well as she has at a still relatively young age is still a great feat. (I tend to think that while she’s absolutely not a joke in power by any stretch, she’s less powerful than Twilight in raw power, like say, 70-80% as strong. She’s never lifted an Ursa Minor, in any case)

@GenericArchangel  
If that’s so how does starswirl know how to turn ponies into alicorns?

@Badumsquish  
A detailed theory!
 
 
@AC97  
And beating an alicorn in that area makes Star Swirl more impressive too. (Or perhaps just more aggressive?)
 
And if you’re talking about Starlight, I agree about the age difference. Dunno what benchmarks we have for her strength - what was her biggest casting besides the timespell?

@Hali the Emoji girl  
Does he? Or had he stumbled on something even he didn’t understand?

@Latecomer
 
Possibly the banishing spell on Discord (which did amount to absolutely nothing, so… meh, I don’t put much stock into it, so maybe her best accomplishment is something along the lines of helping Twilight beat back the Pony of Shadows’ attack, and swapping cutie marks seems like it’s less dependent on raw power, in that I strongly suspect you could stop her from doing that if you shielded the attack; I think Celestia and Luna absolutely could’ve kicked her ass right after she switched their marks, hence part of why she was scared immediately afterwards), but power levels aren’t something generally spelled out in this show in terms of “hey, this guy is x times stronger than you,” I just tend to think she’s a more skilled combatant than Twilight, though perhaps Twilight has improved in that regard as of recent seasons.

I don’t think anyone else was made an alicorn while Luna was on the moon. Think about it- if they turn evil, it’s a one v one for Celestia, and that’s not a risk worth taking. So, a few years before Luna returned, she took an opportunity to line up a ruler for the soon to return Crystal Empire, and to line up a replacement for her and her sister once Luna got back. She deliberately waited until Luna had settled back in as a failsafe if Twilight’s ascension went poorly. Why? Sunset Shimmer. She was supposed to be the replacement for the Sisters, but she went rogue- fortunately, before being given wings, but Celestia learned her lesson anyway.

I feel like the EQG staff are actually making the shipping wars worse with the Rarijack teases.

@icey wicey 1517  
Yeah.

@icey wicey 1517  
Anyone legitimately bothered by those is beyond help.

@GenericArchangel
 
Celestia probably was getting some form of premonitions hinting for her to wait somewhere close to 1,000 years to do anything. She had destiny giving her hope throughout that millennium, probably was one of the only things keeping her going at times. On a related topic, if she were an utterly shitty ruler, I don’t think Equestria would’ve still been standing after all that time.
 
That being said, chances were high that if another alicorn came about, Celestia had great odds of being more than powerful enough to kill them or otherwise defeat them if they became a problem.

@icey wicey 1517
 
Even without the war, the rarijack at times felt that it has overstayed their welcome.