X-class flares per solar cycle

[Jay-B]

I read that the average amount of x-class solar flares is about 11 per solar cycle. I am assuming that most of them are during solar maximum. So does that mean we usually only get 3-4 per year during the top 3 years of heightened solar activity?

[Jesterface23]

The number might be mixed up there. Solar cycles last roughly 11 years. The SWPC has an estimated flare count here per cycle, https://www.swpc.noaa.gov/noaa-scales-explanation#radio-blackouts, or here, https://www.spaceweatherlive.com/en/help/what-are-solar-flares.html.

X-Class solar flares are less likely during solar minimum as activity is low, then the other way around, X-Class flares are most likely around the years where the solar cycle reaches its peak. X-Class flares can occur at almost any time though like in September 2017 when we were declining to solar minimum and we had the strongest flares measured of solar cycle 24.

We just need sunspots with strong magnetic complexity and a bit of luck.

Edited January 11 by Jesterface23

[SpaceWeather5464]

2 hours ago, Jay-B said:

I read that the average amount of x-class solar flares is about 11 per solar cycle. I am assuming that most of them are during solar maximum. So does that mean we usually only get 3-4 per year during the top 3 years of heightened solar activity?

There are 175 X1 flares per cycle and 8 X10+ flares per cycle according to NOAA, And that's just on the earth side which is only like 30% of the Sun, It doesn't count all the powerful flares that happen on the backside of the sun.

[Philalethes]

6 hours ago, SpaceWeather5464 said:

There are 175 X1 flares per cycle and 8 X10+ flares per cycle according to NOAA, And that's just on the earth side which is only like 30% of the Sun, It doesn't count all the powerful flares that happen on the backside of the sun.

We can see virtually half the Solar surface at any given time, if I'm not mistaken. See this post I wrote in a different context, which concludes that we can see ~49.76% of the surface at 1 au.

But your point still remains of course, we're not even seeing all of the flares; right at the limb it might be hard to tell what's what, but if we naively assume that there's roughly the same on the other half too, we get roughly the same amount of X-flares in a cycle as there are days in a year, so conversely if we assume an average of ~11 years per cycle, that means an average cycle would have an X-flare somewhere on the surface every ~11 days, and if evenly distributed that there'd be one on the visible side every ~22 days, roughly every three weeks. Will be interesting to see how SC25 stacks up in that regard when all is said and done.

[Jesterface23]

We can get weaker measurements of flares slightly over the limbs as well, just depending on how far over the limb and the size of the flare

[Drax Spacex]

Slicing and dicing the visible solar disk further, it's helpful to keep in mind that the white and red areas in our 2D perspective view are equal areas on the 3D Sun.

https://ibb.co/xCTgzZZ

We will see slightly more flares in (or beyond) the red area compared to the white area, since some flares will be seen from behind the limbs, as Jesterface23 noted.
 

Edited January 11 by Drax Spacex

[Sam Warfel]

Are the stronger flares more likely to extend higher from the surface, and thus be visible further past the limb, than are the smaller flares?  Or does flare strength not necessarily correlate with altitude 

[Vancanneyt Sander]

3 uren geleden, Sam Warfel zei:

Are the stronger flares more likely to extend higher from the surface, and thus be visible further past the limb, than are the smaller flares?  Or does flare strength not necessarily correlate with altitude 

The bigger the region, the bigger the loops as they connect to spots over longer distances. More spots more loops so big regions many loops and bigger loops. During a flare loops break unleashing the mass of the Sun that flows along them into space, after that magnetic reconnection. Conclusion: big regions, bigger loops, higher altitude.

[Sam Warfel]

15 hours ago, Vancanneyt Sander said:

The bigger the region, the bigger the loops as they connect to spots over longer distances. More spots more loops so big regions many loops and bigger loops. During a flare loops break unleashing the mass of the Sun that flows along them into space, after that magnetic reconnection. Conclusion: big regions, bigger loops, higher altitude.

So perhaps indirectly, as many of the strongest flares come from some of the largest ARs. But not directly, and certainly not always. 
Thanks!

[Vancanneyt Sander]

1 uur geleden, Sam Warfel zei:

So perhaps indirectly, as many of the strongest flares come from some of the largest ARs. But not directly, and certainly not always. 
Thanks!

The X28 (X40) was just behind the limb, it was a huge region and we still registered a saturation event (X17+ with correction factor) . The big loops where still towering from behind the limb still registering the very strong event (and the associated CME still had a glancing blow)

[Jay-B]

There will not be any x-class solar flares today. As you can see there have been zero on this day in recorded history!!

[tniickck]

36 minutes ago, Jay-B said:

There will not be any x-class solar flares today. As you can see there have been zero on this day in recorded history!!

that’s not how it works) 

[Jay-B]

34 minutes ago, tniickck said:

that’s not how it works) 

I know. I just thought that might make people laugh. Although there's not much time left for the sun to prove me wrong!! 

Edited January 25 by Jay-B
Clarity

[arjemma]

I really want a satellite that always stays at the farside of the sun that measures solar flares, solar wind and even a coronagraph. I hope that will happen in the future. We at least need a new STEREO A and B.

I am very interested in how many X-eruptions that happens on the farside. Sure I know that it isn't a priority for scientists as those eruptions won't affect earth and therefore that money is better spent elsewhere. However, I think it would bring scientific value and it would help us understand the solar cycles better. Point being, the sun probably has way more X-eruptions than what we can see on our side of the sun. Thankfully we have the Solar Orbiter which happens to be at the farside every now and then because of it's orbit. I just wished we had more.

Edited January 27 by arjemma
Typo