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ANNULAR SOLAR ECLIPSE: It's not a total eclipse, but it's the next best thing. On Sunday, Feb. 26th, the Moon will pass in front of the southern hemisphere sun, covering as much as 99% of the solar disk. Astronomers call this an "annular" solar eclipse. Observers in parts of South America and Africa will be able to witness a magnificent "ring of fire" in the sky as crescent-shaped sunbeams dance on the ground below. Watch this cool animation from ShadowandSubstance.com.
FLYING NORTH? GRAB THE WINDOW SEAT: Notice to air travelers: If you're going to be flying north this month, ask for a window seat. "Last night, flying from Denver to Calgary, I witnessed my first aurora from the window of an airplane over central Alberta," reports Mike Charnick, who took this picture using a hand-held digital camera:
"I just pressed the lens to the glass and held it as steadily as I could for a 10 s exposure," says Charnick. "It may not be the clearest picture, but it was a true gift to see the aurora from 35,000 up in the sky!"
Northern Lights could be a common sight from airplane windows as February comes to an end. Earth is inside a solar wind stream that could influence our planet for the rest of the month. To understand why, read about the gash in the sun's atmosphere, below.
Realtime Aurora Photo Gallery
A GASH IN THE SUN'S ATMOSPHERE: An unusually wide and sinuous hole has opened in the sun's atmosphere, and it is stretching like a gash across the sun's entire southern hemisphere. NASA's Solar Dynamics Observatory photographed the structure using false-color ultraviolet telescopes on Feb. 17th:
This is a "coronal hole" (CH)--a region where magnetic fields open up and allow solar wind to escape. A fan-shaped stream of solar wind flowing from this broad hole will buffet Earth's magnetic field, off and on, for the next two weeks.
Much of the material will pass to the south of our planet, mitigating its impact; this is not considered a major space weather event. Nevertheless, the sustained action of the glancing solar wind will keep Earth's polar magnetic field in an unsettled state through the end of February.
Overall, this is good news for Arctic sky watchers, for whom nightly episodes of auroras can be expected. In fact, the month could end with an impressive light show. Long-range forecasts by NOAA analysts suggest that G1- and G2-class geomagneic storms are possible on Feb. 27th and 28th when Earth passes through the tail-end of the solar wind stream. Free: Aurora Alerts
NEUTRONS IN THE STRATOSPHERE: In a joint operation on Feb.12th, the students of Earth to Sky Calculus and their sister club Earth to Sky Maritime launched a neutron counter to the stratosphere onboard a high altitude balloon. Neutrons are an important form of cosmic radiation because they provide much of the biologically effective radiation dose at altitudes of interest to aviation and space tourism. How are these particles distributed through our atmosphere? This is what we wanted to find out.
We've just finished reducing the data and can report that the experiment was a success. Neutrons were detected throughout the 2 hour flight covering altitudes from ground level to 113,200 ft:
This first data set shows that neutrons, like gamma rays, peak at the entrance to the stratosphere in a layer known as the Regener-Pfotzer Maximum. Moreover, neutron counts are significantly elevated not only in the stratosphere, but also at lower altitudes where planes fly (20,000 ft to 45,000 ft)--something to think about the next time you buy an airline ticket.
We've been monitoring cosmic rays in the atmosphere for more than two years, and find that deep space radiation has been intensifying. Previous payloads measured only X-rays and gamma-rays, however. The addition of a neutron counter to the payload is a major upgrade, providing a more complete picture of the radiation environment. Stay tuned for updates as we improve our technique and gather more data in future flights.
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 Feb. 19, 2017, the network reported 1 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 February 19, 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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