Solar minimum is here - but even now strangely beautiful auroras are dancing around the poles. Deep inside the Arctic Circle, the expert guides of Aurora Holidays in Utsjoki, Finland, can help you chase them. Book now! | | |
GEOMAGNETIC UNREST EXPECTED: A large hole in the sun's atmosphere is facing Earth and spewing a stream of solar wind in our direction. Estimated time of arrival: May 2nd. Minor geomagnetic storms are possible when the gaseous material arrives. Aurora Alerts: SMS Text
NAKED EYE SPRITE STORMS: Have you ever seen a sprite? Some say it's impossible. The strange and fleeting forms of red lightning materialize above thunderheads, then disappear again in less time than it takes to blink. Yet this week veteran sprite chaser Paul Smith says he did see them: "I've watched a number with my bare eyes over the last two big storms in Kansas."
Above: Naked-eye sprites over Kansas on April 28th. Credit: Paul Smith.
"It has been an amazing experience that, quite honestly, has left me somewhat emotional," says Smith. "I am now convinced that before the days of light pollution, these were observed more often than we know."
Sprites are an exotic form of electricity that leap up from storm clouds instead of down like ordinary lightning. Although sprites have been reported for at least a century, many scientists did not believe they existed until after 1989 when sprites were accidentally photographed by researchers from the University of Minnesota and confirmed by video cameras onboard the space shuttle.
Smith has been chasing and photographing sprites for years in the stormy Great Plains around Oklahoma and Kansas. "This is the first time I have seen them with my unaided eyes," he says. "I believe that these were unusually bright." Here are two examples of clusters he caught simultaneously with his eyes and camera.
His eyes registered fewer details than his camera--but he still saw plenty. "The jellyfish shapes I saw had a fiery orange/red color," he adds. "I didn't see the bottoms of the tendrils, but I had an impression of the heads and beads. Storm chasers to the west of me were also viewing with their naked eyes."
The underlying physics of sprites is still not fully understood. Some models hold that cosmic rays help them get started by creating conductive paths in the atmosphere. If cosmic rays do indeed spark sprites, now is a good time to look for them because cosmic rays are nearing a Space Age high.
More examples of naked-eye sprites may be found on Smith's Facebook page.
Realtime Sprite Photo Gallery
LOOKING FOR LIGHTNING IN THE STRATOSPHERE: Yesterday, the students of Earth to Sky Calculus launched a very low frequency (VLF) radio to the edge of space. Its mission: to detect lightning at record-setting altitudes. Designed and built by a team at the Johns Hopkins University Applied Physics Lab (APL), the sensor ascended 34,516 meters (113,241 ft) above the snow-capped Sierra Nevada and White Mountains of central California:
VLF radio antennas can be very large, typically many meters wide and definitely too big for ballooning. Engineers at APL designed an ultracompact antenna that could fit on a balloon platform. Shown above in flight, the innovative antenna is sensitive to radio bursts in the frequency range 15 kHz to 55 kHz. By monitoring such emissions, it can pick up atmospheric lightning happening across the entire USA.
This is the first time an antenna of this type has been flown to the stratosphere. The researchers, led by Alisha Hunt, hope to use these high-altitude observations to improve models of radio noise caused by lightning (an issue of importance to telecommunications) and maybe even detect new types of lightning. Hunt is reducing the data now, so stay tuned!
Free: Spaceweather.com Newsletter
MOTHER'S DAY IS ONLY 2 WEEKS AWAY: Are you looking for an out-of-this world Mother's Day gift? Consider this: Every time the students of Earth to Sky Calculus launch a cosmic ray balloon, they include something extra in the payload--something mom will love:
Every item in the Earth to Sky Store has flown to the edge of space and comes with a greeting card showing the item in flight. The interior of the card tells the story of the gift's journey from launch to landing. Mom-satisfaction guaranteed!
Far Out Gifts: Earth to Sky Store
All sales 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 Apr. 30, 2019, the network reported 18 fireballs.
(17 sporadics, 1 eta Aquariid)
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 30, 2019 there were 1967 potentially hazardous asteroids.
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Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2019 HS | 2019-Apr-25 | 4.3 LD | 7.2 | 13 |
2019 HU2 | 2019-Apr-26 | 15.7 LD | 12.2 | 20 |
2019 GF1 | 2019-Apr-27 | 4.7 LD | 1.9 | 11 |
2019 HS2 | 2019-Apr-28 | 5.1 LD | 12.1 | 18 |
2019 GX5 | 2019-Apr-28 | 7.2 LD | 10.6 | 26 |
2019 HP3 | 2019-Apr-28 | 14 LD | 5.8 | 25 |
2019 HN3 | 2019-Apr-29 | 6.4 LD | 8.1 | 57 |
2019 HM3 | 2019-Apr-30 | 6.3 LD | 5.2 | 15 |
2019 HO3 | 2019-May-01 | 13.8 LD | 18.6 | 69 |
2019 HK | 2019-May-01 | 12.8 LD | 12.9 | 51 |
2019 HW3 | 2019-May-01 | 16 LD | 8.6 | 37 |
2019 HP | 2019-May-03 | 9.3 LD | 5.7 | 26 |
2019 HV3 | 2019-May-04 | 12.4 LD | 10.9 | 56 |
2018 KK1 | 2019-May-05 | 13.9 LD | 13.9 | 71 |
2019 HQ3 | 2019-May-07 | 15.7 LD | 12.7 | 28 |
2017 RC | 2019-May-09 | 14.5 LD | 10.6 | 9 |
2008 HS3 | 2019-May-09 | 14.6 LD | 5.3 | 162 |
2018 VX8 | 2019-May-12 | 6.2 LD | 15.5 | 118 |
2019 GT1 | 2019-May-17 | 6.1 LD | 3.9 | 36 |
2012 KT12 | 2019-May-18 | 3.3 LD | 3.9 | 20 |
2015 KQ18 | 2019-May-25 | 10.7 LD | 13.1 | 30 |
66391 | 2019-May-25 | 13.5 LD | 21.5 | 1780 |
2003 LH | 2019-May-28 | 15.6 LD | 7.4 | 32 |
2011 HP | 2019-May-30 | 12.3 LD | 8.4 | 135 |
2014 MF18 | 2019-Jun-06 | 8.8 LD | 3 | 22 |
441987 | 2019-Jun-24 | 7.7 LD | 12.6 | 178 |
2008 KV2 | 2019-Jun-27 | 17.8 LD | 11.4 | 195 |
2016 NN15 | 2019-Jun-28 | 9.6 LD | 8.4 | 16 |
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 |
SOMETHING NEW! We have developed a new predictive model of aviation radiation. It's called E-RAD--short for Empirical RADiation model. We are constantly flying radiation sensors onboard airplanes over the US and and around the world, so far collecting more than 22,000 gps-tagged radiation measurements. Using this unique dataset, we can predict the dosage on any flight over the USA with an error no worse than 15%.
E-RAD lets us do something new: Every day we monitor approximately 1400 flights criss-crossing the 10 busiest routes in the continental USA. Typically, this includes more than 80,000 passengers per day. E-RAD calculates the radiation exposure for every single flight.
The Hot Flights Table is a daily summary of these calculations. It shows the 5 charter flights with the highest dose rates; the 5 commercial flights with the highest dose rates; 5 commercial flights with near-average dose rates; and the 5 commercial flights with the lowest dose rates. Passengers typically experience dose rates that are 20 to 70 times higher than natural radiation at sea level.
To measure radiation on airplanes, we use the same sensors we fly to the stratosphere onboard Earth to Sky Calculus cosmic ray balloons: neutron bubble chambers and X-ray/gamma-ray Geiger tubes sensitive to energies between 10 keV and 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
Column definitions: (1) The flight number; (2) The maximum dose rate during the flight, expressed in units of natural radiation at sea level; (3) The maximum altitude of the plane in feet above sea level; (4) Departure city; (5) Arrival city; (6) Duration of the flight.
SPACE WEATHER BALLOON DATA: 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 18% since 2015:
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.
En route to the stratosphere, our sensors also pass through aviation altitudes:
In this plot, 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.
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.
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 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 |
| fun to read, but should be taken with a grain of salt! Forecasts looking ahead more than a few days are often wrong. |
| from the NOAA Space Environment Center |
| the underlying science of space weather |
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