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ENTERING THE SOLAR WIND STREAM: Earth is entering a stream of fast-moving solar wind flowing from a large hole in the sun's atmosphere. This is causing the Arctic Circle to glow with green auroras--a hue that could intensify as our planet moves deeper into the stream on Jan. 19th. NOAA forecasters estimate a 60% chance of G1-class geomagnetic storms during the next 24 hours. Free: Aurora Alerts
RARE DOUBLE SUN HALO: Earlier this week, a winter storm passed through Fairbanks, Alaska. In its wake, "it left a lot of ice crystals in the air," says resident Bernard Marschner. "We had a beautiful display of sun halos--including this double halo on Jan. 17th."
The inner ring is a common 22 degree sun halo, caused by sunlight shining through ice crystals shaped like hexagonal prisms. The outer ring is something more exotic.
"It is a 46 degree halo," explains atmospheric optics expert Les Cowley. "They are more rare than many text books and websites would have you believe."
Both 22 and 46 degree halos are caused by the same hexagonal prism ice crystals, but the 46 degree halo is almost always too faint to see. When you see an outer ring, it is usually something else: "A supralateral arc," says Cowley. "These are caused by hexagonal column crystals aligned horizontally in the air and can masquerade as a 46 degree halo."
Marschnet's sighting was the real thing. "We might get more tomorrow with the temperatures supposed to fall to -50 F," he says. Browse the gallery for sightings!
Realtime Space Weather Photo Gallery
VENUS IN A DROP OF WATER: Recipe for a great photo: Splatter a pane of glass with droplets of water. Place the glass in front of the sunset. Point a camera at the droplets and--click!
Photographer John Bell of Haversham, Bucks, UK followed the recipe and obtained the picture above on Jan. 17, 2017.
"I had been looking at macro photos of flowers through droplets and thought I'd try the same with the evening sky," explains Bell. "I taped a photoframe glass to a tree branch in my garden and framed the droplets using my Canon 5D MK2 with a sigma 106mm macro lens. The view was of Venus by a neighbour's tree."
Water droplets act as inverting lenses, so in the original photo the sunset was upside down. "Easily fixed," says Bell, who restored order by rotating the image 180 degrees. "Focusing was a bit difficult," he adds. "After all, water droplets are not perfect lenses." The result, however, was perfectly beautiful. More exposures are available here.
Realtime Space Weather Photo Gallery
FAR-OUT VALENTINE'S GIFT: For the past two years, Spaceweather.com and the students of Earth to Sky Calculus have been launching balloons to keep track of surging cosmic rays in the atmosphere. Our radiation monitoring program receives no support from corporate sponsors or government grants. Instead, we are crowd-funded. To that end, we offer for your consideration a truly far-out Valentine's gift:
On Dec. 18, 2016, the students of Earth to Sky Calculus flew 30 of these pendants to the stratosphere. You can have one for $69.95--including the rose, which has been pressed for safekeeping. Each order comes with a Valentine's card showing the pendant+rose in flight and telling the story of their trip to the stratosphere.
More out of this world gifts may be found in the Earth to Sky store. All proceeds support cosmic ray balloon flights and STEM education.
Realtime Aurora Photo Gallery
Realtime Airglow Photo Gallery
Realtime Sprite 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 Jan. 19, 2017, the network reported 8 fireballs.
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 January 19, 2017 there were 1761 potentially hazardous asteroids. 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 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.
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