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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POTENT CORONAL HOLE FACES EARTH: A canyon-shaped hole in the sun's atmosphere is facing Earth, and it is spewing a stream of fast-moving solar wind toward our planet. NASA's Solar Dynamics Observatory photographed the giant fissure on March 25th:
This is a "coronal hole" (CH) -- a vast region where the sun's magnetic field opens up and allows solar wind to escape. A gaseous stream flowing from this coronal hole is expected to reach our planet on during the late hours of March 27th and could spark moderately-strong G2-class geomagnetic storms around the poles on March 28th or 29th.
We've seen this coronal hole before. In early March, it lashed Earth's magnetic field with a fast-moving stream that sparked several consecutive days of intense auroras around the poles. The coronal hole is potent because it is spewing solar wind threaded with "negative polarity" magnetic fields. Such fields do a good job connecting to Earth's magnetosphere and energizing geomagnetic storms.
Arctic sky watchers should be alert for auroras early next week. Free: Aurora Alerts
Realtime Aurora Photo Gallery
INFERIOR CONJUNCTION OF VENUS: Today, March 25th, Venus is passing almost directly between Earth and the sun--an event astronomers call "inferior solar conjunction." As Venus passes by with its night side facing Earth, all we can see of the 2nd planet is a slender 1% crescent. Shahrin Ahmad photographed the curve earlier today from Tanjung Bidara, Melaka, Malaysia:
"Venus was a mere 8 degrees from the sun," says Ahmad. "This is my last view of Venus before it goes the other side of the sun and becomes a Morning Star."
Because Venus is so close to the sun, some observers are catching it very close to the horizon just after sunset. The turbulent low atmosphere of Earth has a disturbing effect on Venus' graceful curves. Consider this picture taken by Helio Vital on March 24th from Rio de Janeiro, Brazil:
"Earth's turbulent atmosphere acts like a dynamic set of moving lenses and prisms that play with the point-like light from the stars, causing their apparent brightness, color and even position to fluctuate or 'twinkle'," says Vital. "This effect is usually negligible for planets because the multiple beams of light we receive from their extended disks tend to cancel out. However, the current situation with Venus is different. Its crescent is so thin, each point along the crescent acts a bit like a star--twinkling colorfully as the planet sinks toward the horizon."
Realtime Venus Photo Gallery
THE FLIGHT OF THE EASTERNAUTS: The cosmic ray monitoring program of Spaceweather.com and Earth to Sky Calculus is not supported by government grants or big corporate sponsors. Instead we rely on you. That is, you and the Easternauts:
On March 2nd, the student researchers flew a payload-full of Easter bunnies to the edge of space--and you can have one for $39.95. (Space helmet included!) They make great Easter gifts for young scientists, and all proceeds support STEM education. Each bunny comes with a greeting card showing the Easternaut in flight and telling the story of its journey to the stratosphere and back again.
More far-out gifts may be found in the Earth to Sky store.
Realtime Space Weather 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 Mar. 25, 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 March 25, 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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