Space Weather Update: 10/24/2016
By Spaceweather.com, 10/24/2016
CHANCE OF STORMS THIS WEEK: NOAA forecasters estimate a 45% chance of polar geomagnetic storms on Oct. 25th when Earth enters a stream of high-speed solar wind flowing from a coronal hole on the sun. Analysts say storm levels could reach category G2, which means bright auroras are likely around the Arctic Circle. The glow might even be visible from northern-tier US states such as Minnesota and Michigan Free: Aurora Alerts.
This image from NASA’s Solar Dynamics Observatory shows the outlines of the coronal hole on Oct. 24th:
Coronal holes are, essentially, gaps the sun’s atmosphere where the magnetic field opens up and allows solar wind to escape. They typically appear once or twice a month. This coronal hole is, however, larger than usual, and the emerging stream of solar wind is broad. Earth could be inside it for 3 days or more. Stay tuned for updates as the solar wind approaches.
SINUSOIDAL GROUND CURRENTS IN NORWAY: On Saturday night in the Lofoten Islands of Norway, electrical currents began to flow through the ground, back and forth with a sinusoidal period of 74 seconds. Rob Stammes recorded the phenomenon at his geomagnetic observatory:
“Just after midnight UTC and around 02.36 local time, my ground current instruments picked up these very stable pulsations,” says Stammes.
Currents in the ground are connected to events high overhead. Earth’s magnetic field above the Lofoten Island was also swinging back and forth, inducing amperage in the soil beneath Stamme’s observatory.
These are natural ultra-low frequency oscillations known to researchers as “pulsations continuous” (Pc). The physics is familiar to anyone who has studied bells or resonant cavities. Earth’s magnetic field carves out a cavity in the surrounding solar wind. Pressure fluctuations in the solar wind can excite wave modes in the cavity–usually in a noisy cacophany of many frequencies, but sometimes (like last night) with monochromatic purity. In a sense, Earth’s magnetic field “rings like a bell,” with slow tones that reach all the way down to the ground. References: #1, #2, #3.
Cosmic Rays in the Atmosphere
Updated: Sept. 29 2016 // Next Flight: Oct. 1, 2016
Sept. 20, 2016: Readers, thank you for your patience while we continue to develop this new section of Spaceweather.com. We’ve been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:
This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. Dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.
What is this all about? Approximately once a week, Spaceweather.com and the students of Earth to Sky Calculus fly space weather balloons to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly “down to Earth” form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Our latest measurements show that cosmic rays are intensifying, with an increase of more than 12% since 2015:
Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth’s magnetic field, which helps protect us from deep-space radiation.
The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
The data points in the graph above correspond to the peak of the Reneger-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth’s atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
All Sky Fireball Network
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA’s Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth’s atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On Oct. 24, 2016, the network reported 30 fireballs.
(18 sporadics, 11 Orionids, 1 Leonis Minorid)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Near Earth Asteroids
Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.
On October 24, 2016 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:Asteroid
Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
speed: 397.1 km/sec
density: 9.5 protons/cm3
more data: ACE, DSCOVR
Updated: Today at 2036 UTX-ray Solar Flares
6-hr max: B1 1815 UT Oct24
24-hr: B1 1241 UT Oct24
explanation | more data
Updated: Today at: 2000 UTDaily Sun: 24 Oct 16Sunspot AR2603 is quiet and stable. Solar flare activity remains very low. Credit: SDO/HMI
Sunspot number: 14
What is the sunspot number?
Updated 24 Oct 2016
Current Stretch: 0 days
2016 total: 21 days (8%)
2015 total: 0 days (0%)
2014 total: 1 day (<1%)
2013 total: 0 days (0%)
2012 total: 0 days (0%)
2011 total: 2 days (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)
Updated 24 Oct 2016
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/OvationPlanetary K-index
Now: Kp= 3 quiet
24-hr max: Kp= 4 unsettled
explanation | more data
Interplanetary Mag. Field
Btotal: 5.2 nT
Bz: -4.8 nT south
more data: ACE, DSCOVR
Updated: Today at 2036 UTCoronal Holes: 24 Oct 16
A large coronal hole is turning toward Earth. Solar wind flowing from this structure could reach Earth as early as Oct. 25. Credit: NASA/SDO.Noctilucent Clouds NASA’s AIM spacecraft has suffered an anomaly, and a software patch is required to fix it. As a result, current noctilucent cloud images will not return until late September 2016.
Switch view: Europe, USA, Asia, PolarUpdated at: 08-06-2016 16:55:02
Updated at: 2016 Oct 23 2200 UTC
Probabilities for significant disturbances in Earth’s magnetic field are given for three activity levels: active, minor storm, severe stormUpdated at: 2016 Oct 23 2200 UTCMid-latitudes