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GEOMAGNETIC STORMS TODAY: Minor (
G1) to moderate (
G2) geomagnetic storms are likely on
Oct. 27th as Earth continues to move through a fast-moving stream of solar wind. Polar sky watchers should remain alert for auroras.
Free: Aurora Alerts.
CRAZY PINK AURORAS: During
the ongoing solar wind storm, observers around the Arctic Circle have
been reporting auroras of an unusual color. "Crazy pink," says Frank
Meissner, who took this picture from Tromsø, Norway, on Oct. 26th:
"It was awesome," he says. "Flash-like bursts were zooming all over the sky."
Also watching from Tromsø, veteran
observer Terence Murtagh says "even with many hundreds of aurora
sightings under my belt, I've never witnessed such distinct pink
colors clearly visible and bright to the naked eye. They were
almost too bright to photograph properly."
The pink color is probably a sign of
nitrogen. Most auroras are green--a verdant glow caused by energetic
particles from space hitting oxygen atoms 100 km to 300 km above
Earth's surface. Seldom-seen
pink appears
when the energetic particles descend lower than usual, striking
nitrogen molecules at the 100 km level and below. More examples may be
found in the realtime photo gallery:
AVIATION RADIATION EXPERIMENT IN PROGRESS: Many
people think that only astronauts have to worry about cosmic
radiation. Not so. Regular air travelers are exposed to cosmic rays,
too. This week, Spaceweather.com and the students of
Earth to Sky Calculus
are conducting an experiment in aviation radiation. They are flying
from North America to Europe and back again to measure dose rates on
international flights that cross the Arctic Circle. Here are the data
they collected on Oct. 23-24 en route from Portland, Oregon, to
Frankfurt, Germany:
Radiation levels in the cabin of the Boeing 767 (Condor flight 2091)
tripled within ten minutes after takeoff, and were nearly 40 times
ground level by the time the plane reached cruising altitude at 33,000
feet. There was no solar storm in progress. The extra radiation was
just a regular drizzle of cosmic rays reaching down to aviation
altitudes. This radiation is ever-present and comes from supernovas,
black holes, and other sources across the galaxy.
The
radiation sensors
are the same ones that Earth to Sky Calculus routinely flies onboard
helium balloons to measure cosmic rays in the stratosphere. They
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.
This is part of our
ongoing program to monitor radiation levels inside airplanes. Stay tuned for results from the return flight on Oct. 27th!
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 Oct. 27, 2016, the network reported 20 fireballs.
(14 sporadics, 3 Southern Taurids, 2 Orionids, 1 epsilon Geminid)
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
October 28, 2016 there were 1738
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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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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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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