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PI DAY SOLAR WIND STREAM: A stream of solar wind flowing from a wide gash in the sun's atmosphere is approaching Earth. Estimated time of arrival: March 14 (3.14). Arctic sky watchers should be alert for auroras on Pi Day. Free: Aurora Alerts
EQUINOX CRACKS IN EARTH'S MAGNETIC FIELD: The vernal equinox is less than 10 days away. That means one thing: Cracks are opening in Earth's magnetic field. Researchers have long known that during weeks around equinoxes fissures form in Earth's magnetosphere. Solar wind can pour through the gaps to fuel bright displays of Arctic lights. One such episode occurred on March 9th. "The sky exploded with auroras," reports Kristin Berg, who sends this picture from Tromsø, Norway:
During the display, a stream of solar wind was barely grazing Earth's magnetic field. At this time of year, that's all it takes. Even a gentle gust of solar wind can breach our planet's magnetic defenses.
This is called the the "Russell-McPherron effect," named after the researchers who first explained it. The cracks are opened by the solar wind itself. South-pointing magnetic fields inside the solar wind oppose Earth's north-pointing magnetic field. The two, N vs. S, partially cancel one another, weakening our planet's magnetic defenses. This cancellation can happen at any time of year, but it happens with greatest effect around the equinoxes. Indeed, a 75-year study shows that March is the most geomagnetically active month of the year, followed closely by September-October--a direct result of "equinox cracks."
NASA and European spacecraft have been detecting
these cracks for years. Small ones are about the size of California, and many are wider than the entire planet. While the cracks are open, magnetic fields on Earth are connected to those on the sun. Theoretically, it would be possible to pick a magnetic field line on terra firma and follow it all the way back to the solar surface. There's no danger to people on Earth, however, because our atmosphere protects us, intercepting the rain of particles. The afterglow of this shielding action is called the "aurora borealis."
Stay tuned for more Arctic lights as spring approaches.
Realtime Aurora Photo Gallery
GET READY FOR MOTHER'S DAY: Are you looking for a far-out Mother's Day gift? Consider this: On March 5, 2018, the students of Earth to Sky Calculus flew a cosmic ray balloon to the stratosphere, more than 94,000 feet above Earth's surface. This pendant went along for the ride:
The students are selling these pendants as a fund-raiser for their cosmic ray monitoring program. You can have one for $99.95. Each pendant comes with a greeting card showing the jewelry in flight and telling the story of its journey to the stratosphere and back again. Mom-satisfaction guaranteed!
Far Out Gifts: Earth to Sky Store
All proceeds support hands-on STEM education
THE SUN IS BLANK: Sunspots are becoming scarce. So far in 2018, the sun has been blank--that is, without sunspots--for 36 days. That's more than half of the time. Inspect the face of today's sun:
Could you find any dark cores? Answer: No. The last time the sun was blank more than 50% of the time was in 2009, near the end of the deepest Solar Minimum of the Space Age. Now the sun is entering a new Solar Minimum, and it is shaping up to be even deeper than before.
Periods of spotlessness are a normal part of the 11-year solar cycle. However, the current Solar Minimum may be remarkable as the ambient solar wind and its magnetic field are weakening to low levels never before seen in the Space Age. The flagging pressure of the solar wind, in turn, is allowing more cosmic rays to penetrate the solar system. These rays are being detected not only by NASA spacecraft in the Earth-Moon system, but also by space weather balloons in Earth's atmosphere. Read "The Worsening Cosmic Ray Situation" to learn more about this phenomenon.
Realtime Space Weather Photo Gallery
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 Mar. 11, 2018, the network reported 1 fireballs.
(1 sporadic)
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]
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 March 11, 2018 there were 1882 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2003 EM1 | 2018-Mar-07 | 16.6 LD | 8 | 45 |
2017 VR12 | 2018-Mar-07 | 3.8 LD | 6.3 | 269 |
2018 ES1 | 2018-Mar-07 | 2.9 LD | 13.7 | 16 |
2018 BK7 | 2018-Mar-09 | 10.2 LD | 8.7 | 74 |
2015 DK200 | 2018-Mar-10 | 7 LD | 8 | 27 |
2018 DY3 | 2018-Mar-11 | 5.3 LD | 8 | 21 |
2018 EF1 | 2018-Mar-12 | 11.5 LD | 8.8 | 49 |
2018 EX | 2018-Mar-12 | 12.5 LD | 2.9 | 14 |
2018 EU1 | 2018-Mar-14 | 13.5 LD | 11.8 | 16 |
2018 EH | 2018-Mar-15 | 9.2 LD | 11 | 48 |
2018 ET1 | 2018-Mar-18 | 4.4 LD | 6 | 18 |
2018 EC1 | 2018-Mar-18 | 12.6 LD | 8.7 | 20 |
2018 EV1 | 2018-Mar-22 | 7.7 LD | 11.2 | 29 |
2018 DH1 | 2018-Mar-27 | 9.2 LD | 14.4 | 224 |
2016 SR2 | 2018-Mar-28 | 18.7 LD | 7.3 | 20 |
2010 GD35 | 2018-Mar-31 | 15.5 LD | 11.6 | 45 |
2004 FG29 | 2018-Apr-02 | 4 LD | 14.9 | 22 |
2018 ER1 | 2018-Apr-02 | 15.6 LD | 4 | 26 |
2018 EB | 2018-Apr-04 | 10.3 LD | 15 | 166 |
363599 | 2018-Apr-12 | 19.3 LD | 24.5 | 224 |
2014 UR | 2018-Apr-14 | 9.3 LD | 4.4 | 17 |
2016 JP | 2018-Apr-20 | 12 LD | 12.7 | 214 |
2012 XL16 | 2018-Apr-23 | 15.8 LD | 6.1 | 28 |
2013 US3 | 2018-Apr-29 | 10.1 LD | 7.7 | 214 |
2002 JR100 | 2018-Apr-29 | 10.8 LD | 7.7 | 49 |
1999 FN19 | 2018-May-07 | 9.7 LD | 5.7 | 118 |
2016 JQ5 | 2018-May-08 | 6.3 LD | 10.4 | 9 |
388945 | 2018-May-09 | 6.5 LD | 9 | 295 |
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. | Cosmic Rays in the Atmosphere |
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 13% 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.
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