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AURORAS LOVE EQUINOXES: At this time of year, even a gentle gust of solar wind can spark auroras. NOAA forecasters say that such a gust is coming on Sept. 25th when a stream of solar wind flowing from a minor coronal hole is expected to reach Earth. High-latitude sky watchers should be alert for Northern Lights. Free: Space Weather Alerts
A BEAUTIFUL COINCIDENCE: What are the odds? Catching a lunar rainbow beneath a ribbon of green auroras is rare. Yet it happened twice this week in Iceland. Here is the first time. And here is the second:
"Big rain clouds had been rolling over the whole day with good gaps in between," says photographer Sigurdur William Brynjarsson, who took the picture on Sept. 20th from Reykjanes, Iceland. "The Moon was almost full and aurora activity was picking up. I knew conditions were perfect to capture a lunar rainbow with the Northern Lights together."
"I've never witnessed a lunar rainbow and lady Aurora dancing hand in hand before," he adds. "What a night... =) "
Now that autumn has arrived, rainclouds are mixing with auroras around the Arctic Circle on a regular basis. Those raindrops will turn into snowflakes as winter approaches. Until then, keep an eye on the photo gallery for more moonbows in the Arctic night.
Realtime
Aurora Photo Gallery
WATCH OUT FOR THE EVENING STAR: Sky watchers, keep an eye on the sunset. Venus is emerging from the glare of the sun, climbing higher in the evening sky as September comes to an end. Frank A. Rodriguez sends this picture from Gran Canaria in the Canary Islands:
"I caught Venus shining next to Roque Nublo, an enormous basalt monolith of 80 meters located in the center of the island," says Rodriguez. "In the distance we can see the Teide volcano on the island of Tenerife, about 106 km away. It is the highest point in Spain."
Graphic artist Larry Koehn has created an excellent animation showing how Venus will become even more visible in the weeks and months ahead. A date of special interest is Oct. 3rd when Venus poses next to the slender crescent Moon: sky map. Mark your calendar and enjoy the show.
Realtime
Space Weather Photo Gallery
Realtime
Sprite Photo Gallery
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Cosmic Rays in the Atmosphere |
Updated: Sept. 20, 2016 // Next Flight: Sept. 27, 2016
Sept. 20, 2016: 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.
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 Sep. 24, 2016, the network reported 23 fireballs.
(23 sporadics)
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
September 25, 2016 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.
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The
official U.S. government space weather bureau |
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The
first place to look for information about sundogs,
pillars, rainbows and related phenomena. |
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Researchers
call it a "Hubble for the sun." SDO
is the most advanced solar observatory ever. |
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3D
views of the sun from NASA's Solar and Terrestrial
Relations Observatory |
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Realtime
and archival images of the Sun from SOHO. |
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from
the NOAA Space Environment Center |
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a proud supporter of science education and Spaceweather.com |
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the
underlying science of space weather |
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