INBOUND EARTH DIRECTED---X-FLARE! Big sunspot AR1520 unleashed an X1.4-class solar flare

[Mary]

Should I bring in the laundry?

That's funny...!!!

fwiw I couldn't get online last night - I didn't use the phone or teevee so I don't know if anything went wrong there. Radio station seemed okay - seeing as it goes in and out on a good day

M~~

[rhughe13]

The CME took the light rail here. Expected to arrive tonight (Friday) 8:00 p.m. - 10:00 a.m. Saturday Central time.

[ainitfunny]

http://www.spaceweather.com/

REVISED FORECAST: The CME launched toward Earth by yesterday's X-flare is moving faster than originally thought. Analysts at the Goddard Space Weather Lab have revised their forecast accordingly, advancing the cloud's expected arrival time to 09:17 UT (5:17 am EDT) on Saturday, July 14th. Weekend auroras are likely.

[almost ready]

I seem to recall during the last solar maximum some of the biggest CME's traveled faster than expected.

hmmmm

will look for auroras tonight

[Heliobas Disciple]

http://www.washingtonpost.com/blogs/...06hW_blog.html
(fair use applies)

Solar storm incoming: Federal agencies provide inconsistent, confusing information
By Jason Samnow
Posted at 12:31 PM ET, 07/13/2012

A wave of plasma stoked by an X-class solar flare, the most intense type, is headed towards Earth. This blast of charged particles, known as a coronal mass ejection (CME), is forecast to ignite a geomagnetic storm on Earth over the weekend. NOAA predicts it will be minor, maybe moderate. NASA says it will be moderate to severe.

I ask: which intensity will it be and why aren’t these two science agencies on the same page?

The intensity of the inbound CME matters.

If NOAA’s right, and the ensuing geomagnetic storm is minor, it’s no big deal. It means the high latitudes could be treated to some brilliant auroras over the weekend with few, if any, negative effects on earth-orbiting satellites or the power grid.

On the other hand, if NASA’s right, and the geomagnetic storm is strong to severe, Earth-orbiting satellites could get disoriented and the electrical grid, according to NOAA, could experience “widespread voltage control problems” among other issues. Aurora could be seen as far south as Alabama and northern California.

NOAA and NASA’s predictions about the CME also differ on timing. Last night, NOAA was forecasting a 1 a.m. Saturday arrival of the CME while NASA projected a 6:20 a.m arrival. NOAA has since revised its estimate to 9:00 a.m. NASA tweaked its estimate to 5:17 a.m.

The differences in these predictions raise the question why two government agencies aren’t coordinating and issuing one clear, consistent forecast along with estimates of the uncertainty.

Consider this scenario: A hurricane is approaching the East Coast. What if one U.S. government agency predicted the storm would make landfall as a category 1 to maybe category 2 storm, at worst, while another agency forecast the storm to reach the category 2, 3 or even 4 level? Imagine the widespread confusion that would ensue. How would anyone know if and how to prepare?

There’s a reason the National Hurricane Center closely works with local National Weather Service offices to coordinate hurricane and tropical storm information.

This needs to happen with NOAA and NASA and space weather.

The differences in the geomagnetic storm forecasts for the weekend probably reflect different roles and responsibilities in space weather at the two agencies. NOAA is the nation’s official source of alerts, watches and warnings about space weather and its impacts. NASA’s primary motivation for space weather forecasting is more specialized for “addressing the space weather needs of NASA’s robotic missions”.

Based on these different functions, it would appear NOAA’s information should be considered the most authorative and credible for impacts on Earth and NASA the go-to source for spacecraft. But while NOAA may well be the “official” source of information for our planet, the public and media take what NASA says seriously and NASA’s issuing Earth-based forecasts.

Citing NASA information, the very popular SpaceWeather.com website writes [bold text conveys my added emphasis] “According to a forecast track prepared by analysts at the [NASA] Goddard Space Weather Lab, the CME will hit Earth on July 14th around 10:20 UT (+/- 7 hours) and could spark strong geomagnetic storms.”

Contrast this with NOAA’s statement on its public Facebook page last night to expect [bold text conveys my added emphasis] “only minor geomagnetic storming here when the blast arrives likely Saturday, with few impacts noticeable to most people.”

The discrepancies between NOAA and NASA’s information are made worse by the fact their main website updates (on SpaceWeather.gov and the NASA Goddard Space Weather Center) are seldom accessible to the layperson.

Consider NOAA’s latest update, replete with acronyms and technical terms that non-specialists are likely to have trouble understanding:

The latest model run now indicates the CME associated with yesterday’s R3 (Strong) Radio Blackout event will impact the earth’s magnetic field around 9:00 a.m. EDT (1300 UTC) on Saturday, July 14. SWPC is forecasting category G1 (Minor) Geomagnetic Storm activity then, with a chance of G2 (Moderate) levels at times through July 15. The S1 (Minor) Solar Radiation Storm persists just above event threshold. Region 1520 has decayed in the past 12 hours, but is still potentially eruptive.

Here’s an excerpt from NASA’s latest update - which is no better:

Based on preliminary heliospheric modeling carried out at NASA GSFC Space Weather Center, it is estimated that the CME may impact Earth, Messenger, Spitzer, MSL, Mars. Simulations indicate that the leading edge of the CME will reach Earth at about 2012-07-14T09:17Z (plus minus 7 hours). The roughly estimated expected range of the Kp maximum (Kp is a measure of geomagnetic disturbance levels ranging 0 - 9) is 6-8 (moderate to severe).

Why don’t these agencies prominently publish forecasts and explanations in plain English on their main websites for events attracting media attention?

This is a sorry state of affairs and I’d have to give NOAA and NASA very low marks for their space weather communication efforts.

I fully recognize forecasting space weather events is in*cred*ibly challenging and complex and that these two agencies have different scientists with different sets of expertise and different tools in their toolboxes.

But this does not absolve these Federal agencies from working together to provide clear, consistent information.

At some point in the future - especially with the solar cycle nearing its peak, it’s possible that a severe geomagnetic storm could threaten Earth with serious implications for satellite-based navigation and our power grid.

Related: Are we ready yet for potentially disastrous impacts of space weather?

The stakes are high, and it’s unfortunate, at the moment, we cannot rely on Federal government to provide particularly helpful, harmonized information.

(Note: This morning, I contacted both NOAA and NASA to comment on these issues, and have not yet received responses except from NOAA to affirm they are the official source of space weather forecasts. I will publish anything more substantive I hear back from either agency.)

[Warthog]

X-Class Solar Flare, Strongest Kind, Erupts From Giant Sunspot 'AR1520'


Posted: 07/13/2012 8:36 am Updated: 07/13/2012 2:24 pm


By: Tariq Malik
Published: 07/12/2012 02:36 PM EDT on SPACE.com

The sun unleashed a huge flare Thursday (July 12), the second major solar storm to erupt from our star in less than a week.

The solar flare peaked at 12:52 p.m. EDT (1652 GMT) as an X-class sun storm, the most powerful type of flare the suncan have.

"It erupted from Active Region 1520, which rotated into view on July 6," NASA officials said in an alert. Active Region 1520, or AR1520, is a giant sunspot currently facing Earth.

According to NASA and the Space Weather Prediction Center (SPWC), which is operated by the U.S. National Oceanic and Atmospheric Administration, today's sun storm registered as an X1.4-class solar flare. It is more powerful than the X1.1 flare that erupted on July 6 from another giant sunspot known as AR1515, making this latest tempest the strongest solar storm of the summer so far.

The sunspot region AR1520 could be up to 186,411 miles (300,000 kilometers) long at its peak, solar astrophysicist C. Alex Young of NASA's Goddard Space Flight Center told SPACE.com. It is about 50 percent larger than last week's sunspot AR1515

"It's quite extensive," Young said, adding that sunspots the size of AR1520 are normal as the sun nears its peak of its weather cycle in 2013.

But while sunspot AR1520 may sound like a solar behemoth, it is actually a relatively modest sunspot example, and promises more sun storms to come, Dean Pesnell, project scientist for NASA's Solar Dynamics Observatory, told SPACE.com.

"It's certainly not done. It's only halfway across the face of the sun right now," Pesnell said from the Goddard center in Greenbelt, Md., which oversees the sun-watching SDO mission. "We'll be able to watch it from the Earth for at least another week."

The SDO spacecraft captured a video of the huge X1.4 solar flare and is one of several spacecraft keeping a constant watch on the sun's weather cycle.

Because the solar flare erupted toward Earth, it sent a wave of charged particles toward our planet that could slightly amp up northern lights displays. It caused a strong radio blackout for some high-frequency communications systems, according to SWPC officials.

NASA and SWPC officials said the flare did trigger a huge eruption of solar plasma, known as a coronal mass ejection or CME, which is expected to reach Earth at 1 a.m. EDT (0500 GMT) on Saturday (July 14).Young said that an early analysis suggests the coronal mass ejection sent a wave of plasma toward Earth at a speed of 3.1 million mph (5 million kph or about 1,400 km per second). While it may spark a minor geomagnetic storm, power planets, satellites and astronauts need not worry, he added.

"At this point, I think the impact is going to be relatively minor," Young said.

X-class solar flares are the strongest type of storms that occur on the sun. When aimed at Earth, the most powerful X-class flares can endanger satellites and astronauts in space, interfere with navigation and communications signals, and damage power system infrastructure on our planet.

Today's solar flare marks the sixth X-class solar flare of the year. While it is the strongest yet of the summer season, which began in late June, it is not the most powerful sun storm of 2012. That title is currently held by a March event that unleashed an intense X5.4-class solar flare.

The sun is currently in the midst of an active phase of its 11-year solar weather cycle. The current cycle is called Solar Cycle 24.
http://www.huffingtonpost.com/2012/0...6pLid%3D178696

[Countrymouse]

So when---exactly---can the folks in EST (EDT) expect this thing to hit?

I need to know because my son's having a bunch of his friends here overnight for a party, and I may need to tell them they need to turn off and unplug the computer from the video games by a certain time (I'm thinking 2 am at this point---is that safe?)

Need some help here....anyone?

[Be Well]

I keep checking to find out too....

[NBCsurvivor]

So when---exactly---can the folks in EST (EDT) expect this thing to hit?

I need to know because my son's having a bunch of his friends here overnight for a party, and I may need to tell them they need to turn off and unplug the computer from the video games by a certain time (I'm thinking 2 am at this point---is that safe?)



Need some help here....anyone?

It wasn't that bad of an X-Flare. If you want to run a drill for around 2am that would be a good preparedness exercise though. Then, later, you might be able to see some aurora if you're lucky.

[NBCsurvivor]

dup.

[NBCsurvivor]

CME Update: The WSA-Enlil Solar Wind Prediction has been updated and is calling for the CME Plasma Cloud to sweep past Earth by 12:00 UTC (8:00am EST) early Saturday morning (July 14). The Goddard Space Center prediction has it forecast for 3 hours earlier. The latest model shows a Solar Wind increase to near 700 km/s. Visit the following LINK to watch the latest animation.
http://www.solarham.net/cmewatch2.htm

[homecanner1]

interesting, is that roughly 7:14 am on 7/14 Tehran time?

[Countrymouse]

interesting, is that roughly 7:14 am on 7/14 Tehran time?

Now, if true, that WOULD be interesting indeed....

[ainitfunny]

So when---exactly---can the folks in EST (EDT) expect this thing to hit?

I need to know because my son's having a bunch of his friends here overnight for a party, and I may need to tell them they need to turn off and unplug the computer from the video games by a certain time (I'm thinking 2 am at this point---is that safe?)

Need some help here....anyone?

I told you, a couple posts above your post:

http://www.spaceweather.com/



REVISED FORECAST: The CME launched toward Earth by yesterday's X-flare is moving faster than originally thought. Analysts at the Goddard Space Weather Lab have revised their forecast accordingly, advancing the cloud's expected arrival time to 09:17 UT (5:17 am EDT) on Saturday, July 14th. Weekend auroras are likely.

[Countrymouse]

I told you, a couple posts above your post:

Yes, aif, but then the following posts were all about how there are major discrepancies and disagreements between the "major" sources giving out information on the flare, so it was very confusing as to which one I should listen to or believe.

[SIRR1]

Ainitfunny who are we suppost to believe to have the most accurate forcast?

Goddard or Space Weather who both have different times and forcasts?

This time it's ok to have different forcasts and ETA's because IMO it will be a minor event.

What about in the future when the sun does launches a big damaging CME towards earth, will we still have two .gov agencies giving different forcasts with one saying to go play at the beach while the other agency says to hunker down...

Maybe its good to have two agencies giving inbound space forcasts just to keep the other honest but it would be nice for one of the two agencies come out and speak in laymen's terms saying it will hit around 9 am est and it may be a good idea to be inside for a few hours, not this mumbo jumbo plus or minus universal time crap with a k-2 level impact?

Come up with a time most Americans can understand with one scale that determins good, bad and oh shit it's going to hit the fan scales and stop giving forcasts that only scientists can figure out.

And thats all I have to say on the subject mam!

SIRR1

[Hansa44]

Ainitfunny who are we suppost to believe to have the most accurate forcast?

Goddard or Space Weather who both have different times and forcasts?

This time it's ok to have different forcasts and ETA's because IMO it will be a minor event.

What about in the future when the sun does launches a big damaging CME towards earth, will we still have two .gov agencies giving different forcasts with one saying to go play at the beach while the other agency says to hunker down...

Maybe its good to have two agencies giving inbound space forcasts just to keep the other honest but it would be nice for one of the two agencies come out and speak in laymen's terms saying it will hit around 9 am est and it may be a good idea to be inside for a few hours, not this mumbo jumbo plus or minus universal time crap with a k-2 level impact?

Come up with a time most Americans can understand with one scale that determins good, bad and oh shit it's going to hit the fan scales and stop giving forcasts that only scientists can figure out.

And thats all I have to say on the subject mam!SIRR1

Did I miss something? Is it a good idea to be indoors for a few hours. In my case it doesn't matter. I'll be asleep. But I should tell my DD and SIL.

[ainitfunny]

Ainitfunny who are we suppost to believe to have the most accurate forcast?

Goddard or Space Weather who both have different times and forcasts?

This time it's ok to have different forcasts and ETA's because IMO it will be a minor event.

What about in the future when the sun does launches a big damaging CME towards earth, will we still have two .gov agencies giving different forcasts with one saying to go play at the beach while the other agency says to hunker down...

Maybe its good to have two agencies giving inbound space forcasts just to keep the other honest but it would be nice for one of the two agencies come out and speak in laymen's terms saying it will hit around 9 am est and it may be a good idea to be inside for a few hours, not this mumbo jumbo plus or minus universal time crap with a k-2 level impact?

Come up with a time most Americans can understand with one scale that determins good, bad and oh shit it's going to hit the fan scales and stop giving forcasts that only scientists can figure out.

And thats all I have to say on the subject mam!

SIRR1

Did I miss something? Is it a good idea to be indoors for a few hours. In my case it doesn't matter. I'll be asleep. But I should tell my DD and SIL.

Spaceweather is quoting Goddard, Goddard IS A BRANCH OF NASA.

AT First they (Goddard) said 9am EDTSat, then they(Goddard) moved it up to 7am EDT, NOW it is 5:17am EDT Sat (tomorrow) Soaceweather just relayed NASA(Goddard's) figures as they became revised and more accurate.

THIS CME is only an X 1.4 , WAIT till we get another X28 to get worried.
The most I am going to do is make sure I have a flashlight within reach when I go to bed TONIGHT, if the power goes out for a while.

[Hansa44]

Spaceweather is quoting Goddard, Goddard IS A BRANCH OF NASA.

AT First they (Goddard) said 9am EDTSat, then they(Goddard) moved it up to 7am EDT, NOW it is 5:17am EDT Sat (tomorrow) Soaceweather just relayed NASA(Goddard's) figures as they became revised and more accurate.

THIS CME is only an X 1.4 , WAIT till we get another X28 to get worried.
The most I am going to do is make sure I have a flashlight within reach when I go to bed TONIGHT, if the power goes out for a while.

Thanks aif. The flashlight thing is a good idea.

[Dusty Lady]

Why hasn't anybody mentioned the fact that we get bombarded with solar radiation from this solar belch? The plasma mentioned in the articles is in fact radiation. Good, bad or indifferent I have no idea, maybe it changes our dna, maybe it effects our behavior or lack of. Maybe the radiation heating our Earth is what caused the earthquakes which always follow these things.

Just thinking outloud....the Lab is looking at me now like I really am nuts.

[Heliobas Disciple]

Ainitfunny who are we suppost to believe to have the most accurate forcast?

Goddard or Space Weather who both have different times and forcasts?

SIRR1,

It's NOAA and NASA/Goddard/Space Weather who have different times and forecasts. NOAA is the official 'watcher of the sun' but NASA/Goddard, which has the spaceweather page, does its own calculations and the two don't always match.

From the article I quoted in Post 45 above:

NOAA is the nation’s official source of alerts, watches and warnings about space weather and its impacts. NASA’s primary motivation for space weather forecasting is more specialized for “addressing the space weather needs of NASA’s robotic missions”.

Based on these different functions, it would appear NOAA’s information should be considered the most authorative and credible for impacts on Earth and NASA the go-to source for spacecraft. But while NOAA may well be the “official” source of information for our planet, the public and media take what NASA says seriously and NASA’s issuing Earth-based forecasts.

Excerpt from http://www.washingtonpost.com/blogs/...06hW_blog.html (fair use applies)

HD

[NBCsurvivor]

The latest geomagnetic storm predictions "would indicate aurora down to the northern US," C. Alex Young, a solar astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., told SPACE.com in an email update.

Earlier forecasts had hinted that this weekend's light shows could reach as far south as Alabama. But further number-crunching today scaled back estimates of the coming geomagnetic storm's severity, Young said, suggesting a more limited auroral reach.

http://www.space.com/16572-northern-...e-fallout.html

[NBCsurvivor]

Ya know what's neat though? Comet 96P/Maccholz is going to be within 0.13 AU of the sun here in the next day or so. We've all seen how the sun reacts to comets sometimes.

Interesting times...


Periodic comet 96P/Maccholz is passing by the sun today deep inside the orbit of Mercury. At closest approach, the icy visitor from the outer solar system will be less than 12 million miles (0.13 AU) from the solar surface. Coronagraphs onboard the Solar and Heliospheric Observatory are monitoring the encounte

http://www.sott.net/articles/show/24...-the-Sun-Today

[sthrnfriedrocker]

I'll be up to see what can be seen from my neck of the woods in Northern OK, why not.

[NBCsurvivor]

I'll be up to see what can be seen from my neck of the woods in Northern OK, why not.

If you see anything try to get a pic and post it please. We would all enjoy that I'm sure.

[Shinmen Takezo]

For those of us with little knowledge,
..what's it mean?

In short--it means absolutely nothing.

These flares occur quite often.
Sometimes they are huge, most times they are not.

A massive, massive CME is rare--and they do happen.
It will affect radio transmission, etc. They will affect sattelites and so on.
It would have to be a super massive CME to affect the electrical grid... one such thing occured in the 1800's when a CME knocked down telegraph communications.

http://en.wikipedia.org/wiki/Solar_storm_of_1859

But would one like this affect the power grid?!
Hard to tell. The system is more robust than a simple telegraph array/system.
It would affect radio communications, that's for sure... and television transmitted.

There is not much to worry about.
What you really have to worry about is a nearby star exploding--and then pulsing the Earth with X and Gama rays.
Yes this could happen. Stars explode most every day in this galaxy.
Even something within 10 light years would have a massive effect on the Earth.

[VesperSparrow]

Why is it....EVERYTIME there is one of these doohickies going on...it is raining and cloudy? I got woke up with arrows and daggers stabbing my head again and here is a another chance to see something epic in the sky but NO...rain and stormy.....

[NBCsurvivor]

Why is it....EVERYTIME there is one of these doohickies going on...it is raining and cloudy? I got woke up with arrows and daggers stabbing my head again and here is a another chance to see something epic in the sky but NO...rain and stormy.....

Same here if it makes you feel any better.

[NBCsurvivor]

Updated 7/14/2012 @ 07:20 UTC
Incoming CME Watch
An incoming Coronal Mass Ejection (CME) is expected this morning and could lead to Geomagnetic Storming at high latitudes. The plasma cloud was generated by an X1.4 Solar Flare on Thursday around Sunspot 1520. Continue to monitor the ACE Spacecraft Data for detection of the expected interplanetary shock. In the graph below, you will be looking for a sharp increase in solar wind speed (yellow line).

http://www.solarham.net/

[sthrnfriedrocker]

Can't really see squat in my current locale, too much in the city right now, dangit.

[NBCsurvivor]

Thanks for trying for us anyway sthrnfriedrocker.

[NBCsurvivor]

Roughly 30 minutes to go for impact if the latest forecasts hold true.

[Wise Owl]

Well they are ALL wrong. It's not here yet. All this hyperventilating about a low level X class event and such.

This is where I watch for the incoming.

http://www.swpc.noaa.gov/pmap/index.html

It shows the current Auroral Oval and right now, we are still at a very low level of 3. Yawn.

Until we get slammed with a big one, people need to relax a bit. This one is not going to do much that I can see unless they were lying to us about the size of the CME.

OK?

[Wise Owl]

Ok, it finally arrived. A bit later than advised about but it's here. Currently a level 6. (see pic above from NOAA, which will update when you hit refresh.)

Let's see how stirred up things get.

[Wise Owl]

Looks like it's heading to the SE right towards Maine...maybe we will see the northern lights tonight. Clear skies for a change.

[ItsJustMe]

The Most Powerful Solar Flares Ever Recorded

http://www.spaceweather.com/solarflares/topflares.html

This list is based in part on "Large Solar Flares Since 1976" compiled by IPS Radio & Space Services. The two most recent entries (Dec. 5, 2006; Sept. 7, 2005) are highlighted in red.

----------------------------------------------
Ranking Day/Month/Year X-Ray Class
----------------------------------------------

1 04/11/03 X28+
2 02/04/01 X20.0
2 16/08/89 X20.0
3 28/10/03 X17.2
4 07/09/05 X17
5 06/03/89 X15.0
5 11/07/78 X15.0
6 15/04/01 X14.4
7 24/04/84 X13.0
7 19/10/89 X13.0
8 15/12/82 X12.9
9 06/06/82 X12.0
9 01/06/91 X12.0
9 04/06/91 X12.0
9 06/06/91 X12.0
9 11/06/91 X12.0
9 15/06/91 X12.0
10 17/12/82 X10.1
10 20/05/84 X10.1
11 29/10/03 X10
11 25/01/91 X10.0
11 09/06/91 X10.0
12 09/07/82 X 9.8
12 29/09/89 X 9.8
13 22/03/91 X 9.4
13 06/11/97 X 9.4
14 24/05/90 X 9.3
15 05/12/06 X 9.0
15 06/11/80 X 9.0
15 02/11/92 X 9.0

[NBCsurvivor]

Is it normal for NASA to launch during a geomagnetic storm?

NASA astronaut Suni Williams, Japan Aerospace Exploration Agency astronaut Aki Hoshide and Russian cosmonaut Yuri Malenchenko are set to launch aboard their Soyuz TMA-05M spacecraft from Baikonur on July 14 and dock July 17 to begin a four-month tour of duty aboard the orbiting complex.

http://www.nasa.gov/home/index.html

[NBCsurvivor]

"All eyes are on the solar wind data to note the expected passage on Saturday of a Coronal Mass Ejection (CME) from Thursday's solar event," center officials wrote in an update late Friday (July 13).

The solar storm is not expected to pose a major risk to satellites and spacecraft in orbit, or power systems on Earth, officials have said.

http://www.space.com/16587-solar-sto...earth-now.html

Guess it's no big deal. WHATEVER!! You couldn't pay me to do what they do on a calm day, much less during this.

[Heliobas Disciple]

Looks like it finally got here. A little later than predicted. And not very strong.

BTW, this graphic is real time as of the time I posted it, it does not update.


http://www.n3kl.org/sun/images/noaa_kp_3d.gif?
(fair use applies)

[Heliobas Disciple]

And the update from Spaceweather:

http://www.spaceweather.com/
(fair use applies)

GEOMAGNETIC STORM: A fast-moving CME hit Earth's magnetic field on July 14th at approximately 1800 UT. The impact was not as strong as forecasters expected. Nevertheless, the blow compressed Earth's magnetosphere and sparked a mild (Kp=5) geomagnetic storm, in progress. So far, few sightings of auroras have been reported.

The arrival of the CME shook Earth's magnetic field, which in turn induced electrical currents in the ground at Arctic latitudes. Rob Stammes measured the effect from his magnetic observatory in Lofoten, Norway:



Stammes has observed many CME strikes from his laboratory at the Polar Light Center. He says this one was not particularly strong, at least in terms of ground currents. Relatively weak ground currents are consistent with the muted displays of auroras in the aftermath of the strike.