The Sun
- Thread starter HBS Guy
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spaceweather.com:
Solar wind
speed: 318.0 km/sec
density: 0.66 protons/cm3
X-ray Solar Flares
6-hr max: C2 0629 UT Oct10
24-hr: M2 1231 UT Oct09
Sunspot number: 87
A STREAM OF SOLAR WIND IS APPROACHING EARTH: A hole has opened in the sun's atmosphere, and it is venting a stream of solar wind directly toward Earth. NASA's Solar Dynamics Observatory photographed the dark chasm on Oct. 9th:
This is a "coronal hole" -- a region in the sun's atmosphere where magnetic fields open up and allow solar wind to escape. Coronal holes look dark because the glowing-hot plasma normally contained there is missing.
A stream of solar wind flowing from this coronal hole should reach Earth on Oct. 12th. Its arrival could spark G1-class geomagnetic storms. The odds of storming are increased by the "Russell-McPherron effect," which links the magnetic fields of the sun and Earth during weeks around equinoxes.
spaceweather.com:
Solar wind
speed: 603.5 km/sec
density: 2.12 protons/cm3
X-ray Solar Flares
6-hr max: C6 0846 UT Oct14
24-hr: M2 0041 UT Oct14
Sunspot number: 122
THE CMEs ARE COMING: Active sunspot 4246 has hurled at least two CMEs toward Earth, possibly more. None of them appears to be a major storm cloud, but their combined effect could spark a geomagnetic storm. NOAA forecast models suggest a G1-class event on Oct. 16-17. CME impact alerts: SMS Text.
A POTENTIALLY DANGEROUS SUNSPOT: It's big, and a little weird. Sunspot 4246 has grown rapidly into one of the largest sunspots of Solar Cycle 25. Moreover, it has an unusual mixed-polarity magnetic field, shown in this Oct. 14th magnetic map from NASA's Solar Dynamics Observatory:
Most sunspots have a simpleor
magnetic configuration, like that of an ordinary bar magnet. Nearby sunspot 4248 is a good example. Sunspot 4246 is different, though. It has multiple magnetic poles crowded together in a disorganized fashion.
And that's why this sunspot is potentially dangerous. When opposite polarities mix together too closely--boom!--magnetic reconnection can power strong solar flares. Don't be surprised if there's an X-flare on Oct. 14th
spaceweather.com:
Solar wind
speed: 546.2 km/sec
density: 2.47 protons/cm3
X-ray Solar Flares
6-hr max: M4 0415 UT Oct15
24-hr: M4 0415 UT Oct15
Sunspot number: 108
A POTENTIALLY DANGEROUS SUNSPOT: It's big, and a little weird. Sunspot 4246 has grown rapidly into one of the largest sunspots of Solar Cycle 25. Moreover, it has an unusual mixed-polarity magnetic field, shown in this Oct. 14th magnetic map from NASA's Solar Dynamics Observatory:
Most sunspots have a simpleormagnetic configuration, like that of an ordinary bar magnet. Nearby sunspot 4248 is a good example. Sunspot 4246 is different, though. It has multiple magnetic poles crowded together in a disorganized fashion.
And that's why this sunspot is potentially dangerous. When opposite polarities mix together too closely--boom!--magnetic reconnection can power strong solar flares. Don't be surprised if there's an X-flare on Oct. 14th.
spaceweather.com:
Solar wind
speed: 410.3 km/sec
density: 1.37 protons/cm3
X-ray Solar Flares
6-hr max: C3 0508 UT Oct23
24-hr: C3 0508 UT Oct23
Sunspot number: 117
FARSIDE EXPLOSION (UPDATED): Late on Oct. 21st, something exploded on the farside of the sun. The blast produced a fast and potent CME, shown here in an animation from the Solar and Heliospheric Observatory (SOHO):
The USAF reported Type II radio emissions from this CME with high-velocity drift rates: 2474 km/s--a sign of fast-moving shocks inside the CME. Only a handful of CMEs in the Space Age have moved significantly faster, such as the great CME of Aug. 1972 (2850 km/s) and a CME propelled by an X8 flare in Sept. 2017 (2600--3300 km/s).
Update: New 3D models of this CME from NASA's Moon to Mars Space Weather Analysis Office suggest a lower speed, around 1320 km/s. This is still very fast, but not the record-setter indicated by Type II solar radio emissions.
According to a NASA model, the CME just hit Venus. Venus does not have an internally generated global magnetic field to protect it, so the impact probably eroded some gas from the planet's cloudtops. Venus's crushingly-thick atmosphere won't notice.
The source of the explosion approximately matches the location of old sunspot 4246, currently transiting the farside of the sun. Only a week ago, that dangerous sunspot was facing Earth. ==> We dodged a bullet.
