Lights Over Lapland is excited to announce that our aurora webcam will be up and running 365 days per year! You can now enjoy watching the Midnight Sun and all of the other drama in the sky above Abisko National Park, Sweden here. | | |
INTERPLANETARY SHOCK WAVE: An interplanetary shock wave hit Earth's magnetic field on April 19th around 23:50 UT. When the disturbance arrived, the density of solar wind flowing around our planet abruptly quadrupled and a crack opened in Earth's magnetic field. The resulting G2-class geomagnetic storm sparked unusual "electric blue" auroras.
"I've been flying airplanes for 20 years and photographing aurora for 10 years, but I've never seen anything like this before," reports pilot Matt Melnyk who photographed the display from 39,000 feet:
"Electric blue auroras!" he says. "This was while on a red eye flight from Edmonton to Toronto around 4 am over northern Manitoba. Unbelievable sky. I was able to grab some hasty shots with a cell phone."
Auroras are usually green--a sign of oxygen. Rare blue auroras are caused by nitrogen molecules. Energetic particles striking N2+ at the upper limits of Earth's atmosphere can produce an azure glow during intense geomagnetic storms.
During the storm, Northern Lights spilled across the Canadian border into the United States as far south as Indiana. Hongming Zheng, a student at Purdue University, saw the blue glow just five miles from his dorm:
"I was preparing for bed at 1:32 am on April 20th when I read that there was an Interplanetary Shockwave," says Zheng. "I immediately started driving north to see the show. A weak green wisp showed up at 2am and faded, but shortly after 5am a sudden outburst occurred. Purple pillars were easily visible to the naked eye. It's funny how one minute you are in a humid dorm struggling to get the laundry door closed, and the next minute you are chasing one of the most spectacular phenomenon known to man."
What is an interplanetary shock wave? It is a supersonic disturbance in the gaseous material of the solar wind. These waves are usually delivered by coronal mass ejections (CMEs). Indeed, this one might have been a minor CME that left the sun unrecognized earlier this week.
Alternately, it might have been an unusually sharp co-rotating interaction region (CIR). CIRs are transition zones between slow- and fast-moving streams of solar wind. They contain plasma density gradients and magnetic fields that often do a good job sparking auroras.
High latitude sky watchers should remain alert for auroras on April 20-21 as Earth's magnetic field continues to reverberate from the impact. Free: Aurora Alerts
Realtime Aurora Photo Gallery
MOTHER'S DAY IS JUST 3 WEEKS AWAY: Nothing says "I love you" like a heart-shaped pendant from the edge of space. On March 18, 2018, the students of Earth to Sky Calculus launched an array of cosmic ray sensors to the stratosphere onboard a helium balloon. This Mother's Day gift went along for the ride:
You can have it for $199.95. The students are selling these sterling silver 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
HUBBLE TRANSITS THE MOON: Everyone loves pictures taken by the Hubble Space Telescope. On April 19th, Leo Caldas of Brasilia, Brazil, took a rare picture of the Hubble Space Telescope. He caught the iconic spacecraft transiting the Moon:
With some guidance from Calsky.com, "I was in the right place and time so see this unusual encounter," says Caldas. "At the time of the transit, Hubble was 891 km from me shining like a star of magnitude +3.5."
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 Apr. 20, 2018, the network reported 15 fireballs.
(15 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 April 20, 2018 there were 1907 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2018 GE3 | 2018-Apr-15 | 0.5 LD | 29.6 | 61 |
2018 HM | 2018-Apr-15 | 2.9 LD | 9.3 | 12 |
2018 GC2 | 2018-Apr-17 | 9 LD | 4.9 | 15 |
2018 GP4 | 2018-Apr-17 | 11.4 LD | 9.3 | 18 |
2018 GK4 | 2018-Apr-17 | 5.9 LD | 10.8 | 20 |
2018 GS3 | 2018-Apr-20 | 8.5 LD | 19.8 | 24 |
2016 JP | 2018-Apr-20 | 12 LD | 12.7 | 214 |
2018 GR1 | 2018-Apr-21 | 18.3 LD | 16.4 | 53 |
2018 HN | 2018-Apr-21 | 8 LD | 9.8 | 37 |
2018 GG4 | 2018-Apr-23 | 9.8 LD | 14.9 | 20 |
2012 XL16 | 2018-Apr-23 | 15.8 LD | 6.1 | 28 |
2018 GH | 2018-Apr-25 | 14.6 LD | 10.7 | 89 |
2018 HP | 2018-Apr-26 | 11.6 LD | 10.3 | 19 |
2018 GH5 | 2018-Apr-27 | 12.2 LD | 12.7 | 32 |
2018 GB2 | 2018-Apr-27 | 17.1 LD | 14.6 | 94 |
2013 US3 | 2018-Apr-29 | 10.1 LD | 7.7 | 214 |
2018 GO4 | 2018-Apr-29 | 11.8 LD | 8.6 | 46 |
2018 GY1 | 2018-Apr-29 | 13.2 LD | 16.7 | 139 |
2018 FV4 | 2018-Apr-29 | 17.7 LD | 6.5 | 59 |
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 |
2018 GR2 | 2018-May-11 | 13.4 LD | 9.8 | 110 |
1999 LK1 | 2018-May-15 | 13.3 LD | 10 | 141 |
2018 GL1 | 2018-May-18 | 14.3 LD | 5.2 | 66 |
68347 | 2018-May-29 | 9.5 LD | 13.3 | 389 |
2013 LE7 | 2018-May-31 | 17.8 LD | 1.7 | 12 |
2018 EJ4 | 2018-Jun-10 | 5.6 LD | 6.2 | 195 |
2015 DP155 | 2018-Jun-11 | 9 LD | 4.4 | 170 |
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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| 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
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