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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SOLAR WIND CONTINUES TO BLOW: Minor G1-class geomagnetic storms are circling Earth's poles as our planet spends its 5th day inside a fast-moving stream of solar wind. Arctic and Antarctic sky watchers should remain alert for auroras after local nightfall. Free: Aurora Alerts
Sònia i Joan photographed this display on March 31st from Kabdalis in the Swedish Lapland:
"The auroras were bright and fast," says Joan. "We could see them even through the glare of headlights from passing cars."
Realtime Aurora Photo Gallery
APRIL 1ST COMET FLYBY: Green comet 41P/Tuttle-Giacobini-Kresak is flying over Earth's North Pole this week where sky watchers can find it all night long not far from the bowl of the Big Dipper. At closest approach on April 1st it will be just 21 million km from Earth--an easy target for backyard telescopes and almost visible to the naked eye. Amateur astronomer Yasushi Aoshima sends this picture of the approaching comet from Fukushima, Japan:
"On March 22nd I caught 41P 'eating' M108, the Surfboard Galaxy," says Aoshima. "The comet's green atmosphere appeared to swallow the distant spiral galaxy as it exited Ursa Major."
Why green? Like many comets, 41P has a verdant hue because its atmosphere contains diatomic carbon (C2)--a substance that glows green in the near vacuum of space.
Comet 41P is not only approaching Earth, but also the sun. April 12th is the date of perihelion (minimum distance from the sun). This means we are catching the comet just as solar heating is furiously searing its icy core. The green atmosphere should be well puffed up by streamers of vaporizing gas. Optimistic estimates of the comet's brightness place it at magnitude +6, near the lower limit of naked-eye visibility.
This is not a Great Comet, but it should be a good one. The best time to observe is during the dark hours before sunrise when the green fuzzball is high in the northern sky. If you have a GOTO telescope, you can point it using an ephemeris from the Minor Planet Center. These sky maps show approximately where to look: March 31, April 1, 2.
Realtime Comet Photo Gallery
TOUCHING THE EDGE OF SPACE: On March 10, 2017, the students of Earth to Sky Calculus launched a space weather balloon from the frozen surface of Lake Tornetrask 250 km inside the Arctic Circle. A payload-full of reindeer pendants hitched a ride to the Edge of Space:
You can have one for $129.95. Each glittering pendant comes with a greeting card showing the jewelry in flight and telling the story of its journey 97,000 feet above the Lapland of Northern Sweden. They make great Birthday and Mother's Day gifts.
More far-out gifts may be found in the Earth to Sky store. All proceeds support STEM education and our atmospheric cosmic ray monitoring program.
SUNSPOT SUNSET: Sunspots AR2644 and AR2645 have grown so large that some sky watchers are noticing them as blemishes on the setting sun. Wednesday evening in Girona, Spain, photographer Mohamad Soltanolkotabi went outside to look at the crescent Moon and, when he faced west, captured the sunspots instead:
"The sun was dimmed by low-hanging clouds, which made it possible to photograph these two large sunspots," he explains. "I was located on the grounds of the University of Girona."
These sunspots are large, but not very active. Their magnetic fields are simple and stable, and thus pose little threat for explosive flares. Nevertheless they are photogenic. Warning: Even when the sun is dimmed by low-hanging clouds or smoke, it can still hurt your eyes. If you chose to photograph the low sun, as Soltanolkotabi did, use the camera's LCD screen for safe viewfinding. Never look into the eyepiece of an unfiltered camera or telescope when the sun is in the field of view.
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. 31, 2017, the network reported 37 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 March 31, 2017 there were 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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