Solar X-Flare Blasts Directly Toward Earth

Freshly Exhumed writes with this excerpt from Space Weather: "Big sunspot AR1520 unleashed an X1.4-class solar flare on July 12th at 1653 UT. Because this sunspot is directly facing Earth, everything about the blast was geoeffective. For one thing, it hurled a coronal mass ejection (CME) directly toward our planet. According to a forecast track prepared by analysts at the Goddard Space Weather Lab, the CME will hit Earth on July 14th around 10:20 UT (+/- 7 hours) and could spark strong geomagnetic storms. Sky watchers should be alert for auroras this weekend."

Revised Forcast

[rminsk]

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.

Strong geomagnetic storms?

[Anonymous Coward]

While the news before the fact is great for those of us living some place with a chance of catching the aurora, I don't think there is any indication there will be strong geomagnetic storms. NOAA Space Weather Center [noaa.gov] is predicting only storm level of G1 with a chance of G2, which happens quite frequently. Usually if something big is coming, their alert timeline [noaa.gov] lights up with a lot more than a G1 or warning of A > 20. I've made a habit of taking the 10 seconds to check their alert page every time a relative links or talks about a story of some massive geomagnetic storm coming, and pretty much every time it shows (both before and after) that it was something minor that happens with a frequency of more than once a month.

Not considered a threat to the US power grid

[Animats]

Just checked the PJM [pjm.com] dashboard, which shows what's going on for the power grid in the northeastern US. They haven't put up a Solar Magnetic Disturbance Warning for this event.

NOAA predicts a maximum A index of 25 and a maximum K index of 3 at low latitudes, 6 at high latitudes (Canada, roughly). [noaa.gov] PJM says they issue an alert when there's an A index of 40 or above or a K index of 5 or above. K=6 and 7 level events aren't serious problems; trouble occurs around 8 and 9.

The last event that caused a blackout was in 1989. Since then, more monitoring gear has been added and plans made for when this problem occurs. The basic effect is that the solar wind induces DC currents in the earth, causing a huge ground loop between distant grounding points. This causes DC current to flow through AC high tension lines, which heats up transformers and causes some confusion in measurements. Those DC currents are constantly monitored. When DC flows are observed, the AC currents on the line have to be reduced to prevent transformer overheating. It's an operational problem, but not a disaster.

(If you're really interested in this topic, here's the PJM training presentation that covers solar and magnetic disturbances. [pjm.com] This is the perspective from the people who operate the power grid. "When solar magnetic disturbance is confirmed, Salem 1 and 2 units will reduce to 80% power and Hope Creek to 85% power...")

Re:Is it so wrong?

[amorsen]

Solar irradiation of the earth is 1600 EJ

This is wrong. Solar irradiation at 1 AU is somewhere in the region of 1350W/m^2. The Earth has a diameter of approximately 6371000m, which is a disc of 1.27*10^14 m^2. This gives 1.72*10^17W or 0.172EW. Over a year, 365.25*86400s, this comes to 5.400.000EJ.

Wikipedia is wrong.

In fact, from a different page on Solar energy [wikipedia.org], "Photosynthesis captures approximately 3,000 EJ per year in biomass." Pretty impressive if solar irradiation is only 1,600EJ. And unlike the 1,600 EJ figure, this one actually comes with a useful citation.

The cited page, FAO on Energy conversion by photosynthetic organisms, chapter 2 [fao.org] has this to say:

"Approximately 5.7 x 1024 J of solar energy are irradiated to the earth's surface on an annual basis. Plants and photosynthetic organisms utilize this solar energy in fixing large amounts of CO2 (2x1011 t = 3x1021 J/year), while amounts consumed by human beings are relatively small, (3 x 1020 J/year) (1), representing only 10% of the energy converted during photosynthesis."

So, it is time for you to revise your ideas about how humanity should live.