Directly under the Arctic Circle! Marianne's Arctic Xpress in Tromsø offers fjord, whale and wildlife tours by day, aurora tours by night. Email Marianne for bookings and availability.
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SUBSIDING CHANCE OF FLARES: Earlier this week, solar flare activity was high as sunspot AR2644 unleashed a series of M-class explosions. Now, however, the sun is quieting. AR2644 has rotated off the solar disk and no longer poses a threat for Earth-directed flares. Free: Solar Flare Alerts
GIANT 'ELVE' APPEARS OVER EUROPE: On April 2nd, high above a thunderstorm in the Czech republic, an enormous ring of light appeared in the night sky. Using a low-light video camera, amateur astronomer Martin Popek of Nýdek photographed the 300 km-wide donut hovering near the edge of space:
"It appeared for just a split second alongside the constellation Orion" says Popek.
This is an example of an ELVE (Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources). First seen by cameras on the space shuttle in 1990, ELVEs appear when a pulse of electromagnetic radiation from cloud-to-ground lightning propagates up toward space and hits the base of Earth's ionosphere. A faint ring of deep-red light marks the broad 'spot' where the EMP hits.
"For this to happen, the lightning needs to be very strong--typically 150-350 kilo-Ampères," says Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politècnica de Catalunya. "For comparison, normal cloud-to-ground flashes only reach 10-30 kA."
ELVEs often appear alongside red sprites, which are also sparked by strong lightning. Indeed, Popek's camera caught a cluster of sprites dancing nearby.
ELVEs are elusive--and that's an understatement. Blinking in and out of existence in only 1/1000th of a second, they are completely invisible to the human eye. For comparison, red sprites tend to last for hundredths of a second and regular lightning can scintillate for a second or more. Their brevity explains why ELVEs are a more recent discovery than other lightning-related phenomenon. Learn more about the history and physics of ELVEs here and here.
Realtime Sprite Photo Gallery
JUPITER AT OPPOSITION: This week, the sun, Earth and Jupiter are almost perfectly aligned. Or, as an astronomer would say, "Jupiter is at opposition." From our point of view on Earth, Jupiter and the sun are on opposite sides of the sky:
At opposition, the giant planet rises at sunset and stays up all night long. This is also the time when Jupiter is closest to Earth. Even small telescopes reveal Jupiter's moons and stormy cloud belts. To appreciate the view, cross your eyes and stare into this picture taken by Sylvain Weiller of Jerusalem, Israel:
"This was the view through my 10-inch telescope," says Weiller. By taking the pictures at slightly different times, he allowed the rapid rotation of Jupiter to create a stereoscopic effect. Crossing your eyes and mentally merging the two images, Jupiter pops out of the screen in 3D. (Having trouble? Try the larger version.)
Realtime Jupiter Photo Gallery
TIME TO PLANT YOUR SPACE GARDEN: Northern Spring has arrived, and that means it's time to plant your garden. Your SPACE garden, that is. On March 26th, the students of Earth to Sky Calculus flew a payload-full of tomato and sunflower seeds to the edge of space. Carried 115,500 feet high by a giant helium balloon, the packets experienced temperatures as low as -63 C and cosmic ray dose rates 100 times Earth-normal. Here they are at the apex of the flight:
What will these far-out seeds yield? Find out for yourself! For only $39.95 we will send you a packet of space seeds along with control samples that remained on the ground during the flight. Plant them side by side for a backyard science experiment.
Each shipment comes with a card telling the story of the flight and certifying that the seeds have been to the stratosphere and back again. Please specify your seed preference (Beefsteak tomato, cherry tomato, or sunflower) in the comments box at checkout.
More far-out items may be found in the Earth to Sky store. All proceeds support STEM education and our atmospheric cosmic ray monitoring program. .
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
Realtime Comet 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. 6, 2017, the network reported 17 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 April 6, 2017 there were 1784 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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