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SUBSIDING CHANCE OF STORMS: A co-rotating interaction region (CIR) expected to hit Earth's magnetic field on Aug. 19th did not arrive as expected. Probably, the sharp transition zone between slow- and fast-moving solar wind streams (i.e., the CIR) dissipated before it reached our planet. As a result, NOAA forecasters have downgraded the chance of geomagnetic storms today to only 15%. Aurora alerts: text or voice
SPACE WEATHER BALLOON EXPERIMENT--NOW! For the next fews days, the staff of Spaceweather.com will be busy with a 10,000 mile wide experiment. Together with the students of Earth to Sky Calculus, we are launching space weather balloons from multiple sites in two continents. Here are some of the launch sites:
Our purpose is two-fold:
First, it's a giant experiment in atmospheric radiation. Our payloads contain radiation sensors that allow us to measure cosmic rays from deep space. We will find out how this penetrating form of radiation varies around the Americas at altitudes ranging from ground level to the stratosphere. The results will be especially interesting in Chile, where the balloon will ascend into the South Atlantic Anomaly, a high radiation zone caused by a weakness in Earth's magnetic field.
Second, we're practicing for Aug. 21, 2017--the date of the Great American Solar Eclipse. One year from now, we will launch more than a dozen balloons into the path of totality to photograph the eclipse from the stratosphere and create a unique movie of the Moon's shadow sweeping across North America. Such an ambitious project requires practice, and we're starting now.
The Chilean balloon is scheduled to launch just a few hours from now. Stay tuned for updates.
PLANETS IN THE SUNSET SKY: Venus and Jupiter are converging in the sunset sky for a close encounter on Aug.27th. Yesterday in the Snowy Mountains of NSW Australia, Phil Hart photographed the two bright planets approaching one another with Mercury looking on:
"A highlight of six days backcountry skiing in NSW was the planetary alignment of Venus, Mercury and Jupiter," says Hart. "It took a few nights to get the weather and scenery to cooperate, but after an hour of trapsing around and lying down in the snow, I managed to capture this shot on our last night out."
The view will improve in the evenings ahead as the distance between Jupiter and Venus decreases. At closest approach on Aug 27th, the two worlds will appear only about 1/15th of a degree apart. If you hold a pencil at arm's length, the eraser would cover both planets at once. Moreover, Venus and Jupiter will easily fit within a telescopic field of view--an amazing sight if you have a backyard telescope.
Remember, though, that a telescope is not required. Venus and Jupiter are bright enough to see with the naked eye even from light-polluted urban areas. Try to catch them about 30 minutes after sunset before the sky fades completely black. The sight of two planets in conjunction surrounded by twilight blue is extra-beautiful.
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
Realtime Noctilucent Cloud Photo Gallery
Realtime Sprite 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 Aug. 20, 2016, the network reported 18 fireballs.
(17 sporadics, 1 kappa Cygnid)
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 August 20, 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.
| ||Cosmic Rays in the Atmosphere |
These measurements are based on regular space weather balloon flights: learn more.
|Situation Report -- Oct. 30, 2015 ||Stratospheric Radiation (+37o N) |
|Cosmic ray levels are elevated (+6.1% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month. |
|Sept. 06: 4.14 uSv/hr (414 uRad/hr) |
|Sept. 12: 4.09 uSv/hr (409 uRad/hr) |
|Sept. 23: 4.12 uSv/hr (412 uRad/hr) |
|Sept. 25: 4.16 uSv/hr (416 uRad/hr) |
|Sept. 27: 4.13 uSv/hr (413 uRad/hr) |
|Oct. 11: 4.02 uSv/hr (402 uRad/hr) |
|Oct. 22: 4.11 uSv/hr (411 uRad/hr) |
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. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. For example, here is the data from a flight on Oct. 22, 2015:
Radiation levels peak at the entrance to the stratosphere in a broad region called the "Pfotzer Maximum." This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in about 5 hours.
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.
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| ||3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| ||Realtime and archival images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
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