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CHANCE OF STORMS TODAY: NOAA forecasters estimate a 55% chance of G1-class geomagnetic storms today, March 25th, as a stream of solar wind blows around Earth. The gaseous material is flowing from a southern hole in the sun's atmosphere. Polar sky watchers should be alert for auroras. Free: Aurora Alerts
'TIS THE SEASON FOR 'STEVE': Last night, something happened at the edge of space over Alaska. More than 200 km above Anchorage, a hot ribbon of ionized gas snaked through Earth's magnetosphere, creating a luminous arc that rivaled the Moon in brightness. Sanjana Greenhill witnessed the apparition:
"We noticed this perfect arc developing across the sky," says Greenhill. "It didn't seem like the aurora since it wasn't moving much. The arc got brighter and then faded and then got brighter again. And then it dawned on me, this is STEVE!"
STEVE is an aurora-like phenomenon that researchers are only beginning to understand. For many years, northern sky watchers reported the form occasionally dancing alongside auroras. It was widely called a "proton arc" until researchers pointed out that protons had nothing to do with it. So members of the Alberta Aurora Chasers group gave it a new name: "Steve" (since upgraded to STEVE, an acronym for 'Strong Thermal Emission Velocity Enhancement.')
The first clues to the nature of STEVE came in 2016 when one of the European Space Agency's Swarm satellites encountered the phenomenon. "As the satellite flew straight though 'Steve,' the temperature jumped by 3000°C and the data revealed a 25 km-wide ribbon of gas flowing westwards at about 6 km/s (13,000 mph)," reports Eric Donovan from the University of Calgary.
This ESA animation shows Swarm satellites orbiting Earth above ground cameras observing STEVE
Donovan and a team of colleagues led by Elizabeth MacDonald of NASA's Goddard Space Flight Center have just published a paper on STEVE. In it, they confirm that STEVE is distinct from ordinary auroras, usually forming to the south of active Northern Lights. The mauve and purple colored arcs, they say, are related to supersonic rivers of gas called "subauroral ion drifts" (SAIDs), which flow through Earth's magnetic field. Earth-orbiting satelites have tracked thousands of SAIDs: they tend to appear near latitude +60 degrees, and occur more frequently during spring and fall than summer and winter.
This last point means that now is the season for STEVE. The onset of northern spring seems to lure the arc out of winter hiding.
"I saw STEVE for the first time on March 18th," reports Giuseppe Petricca , who took this sequence of pictures from the Isle of Lewis in Scotland:
"It was an ever-changing tornado, with violet tones, always in movement, always with different shapes," he says. "Another wonder of Nature!"
The mystery of STEVE is far from solved. Researchers still don't understand why STEVE is purple--or for that matter why the underlying rivers of gas should glow at all. "Further spectral analysis and modeling are needed," say MacDonald et al.
In other words, keep an eye out for STEVE.
Realtime "Steve" Photo Gallery
OUT OF THIS WORLD GIFT: It's sterling silver and it comes from space. 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 Mother's Day pendant went along for the ride:
You can have one for $119.95. The students are selling these pendants as a fund-raiser for their cosmic ray monitoring program. All proceeds support atmospheric radiation measurements and hands-on STEM education.
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
Realtime Aurora Photo Gallery
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. 25, 2018, the network reported 3 fireballs.
(3 sporadics)
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 25, 2018 there were 1882 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2018 FX4 | 2018-Mar-20 | 4.1 LD | 22.4 | 27 |
2018 FG1 | 2018-Mar-21 | 4.5 LD | 9.7 | 12 |
2018 FU4 | 2018-Mar-21 | 17 LD | 8.4 | 29 |
2018 ED9 | 2018-Mar-21 | 1.6 LD | 6.1 | 14 |
2018 FR3 | 2018-Mar-22 | 3.2 LD | 7.7 | 13 |
2018 EV1 | 2018-Mar-22 | 7.7 LD | 11.2 | 28 |
2018 FF3 | 2018-Mar-23 | 1.1 LD | 12 | 17 |
2018 FL2 | 2018-Mar-23 | 9 LD | 17.7 | 27 |
2018 FA2 | 2018-Mar-23 | 11.2 LD | 8.2 | 15 |
2018 FZ3 | 2018-Mar-23 | 0.5 LD | 14.1 | 11 |
2018 FC3 | 2018-Mar-23 | 5.3 LD | 15.3 | 11 |
2018 FW1 | 2018-Mar-24 | 9.2 LD | 7.3 | 34 |
2018 FB3 | 2018-Mar-25 | 9.3 LD | 15.9 | 33 |
2018 FQ1 | 2018-Mar-25 | 5.7 LD | 5.9 | 15 |
2018 FR1 | 2018-Mar-26 | 6.2 LD | 12.2 | 17 |
2018 DH1 | 2018-Mar-27 | 9.2 LD | 14.4 | 224 |
2016 SR2 | 2018-Mar-28 | 18.7 LD | 7.3 | 20 |
2018 FU1 | 2018-Mar-28 | 12.3 LD | 5.9 | 15 |
2018 FO4 | 2018-Mar-28 | 7.7 LD | 6.3 | 11 |
2018 FU3 | 2018-Mar-29 | 17.7 LD | 8.4 | 20 |
2018 FE4 | 2018-Mar-29 | 13.3 LD | 20.7 | 35 |
2018 FB | 2018-Mar-29 | 4.9 LD | 8.5 | 61 |
2018 FB2 | 2018-Mar-30 | 10 LD | 6.7 | 26 |
2010 GD35 | 2018-Mar-31 | 15.5 LD | 11.6 | 45 |
2018 EM4 | 2018-Apr-01 | 6.2 LD | 6.2 | 31 |
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 | 10.4 LD | 15.1 | 165 |
2018 FW4 | 2018-Apr-05 | 9.8 LD | 11.6 | 32 |
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 |
2018 FV4 | 2018-Apr-29 | 17.7 LD | 6.5 | 60 |
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 |
1999 LK1 | 2018-May-15 | 13.3 LD | 10 | 141 |
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.
| The official U.S. government space weather bureau |
| The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| Realtime and archival images of the Sun from SOHO. |
| from the NOAA Space Environment Center |
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