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SOLAR SECTOR BOUNDARY CROSSING: On Aug. 28th, Earth will cross a fold in the heliospheric current sheet. This "solar sector boundary crossing" could disturb our planet's magnetic field and spark auroras at high latitudes. NOAA forecasters estimate a 25% chance of G1-class geomagnetic storms. Aurora alerts: text or voice
SUNSET CONJUNCTION: Venus and Jupiter are converging for a beautiful conjunction in the sunset sky. The best place to see it is the southern hemisphere. Helio C. Vital sends this picture from Rio de Janeiro, Brazil:
"Shown in the photos are Venus, Jupiter and Mercury forming a triangle in Rio's evening twilight sky," says Vital. "Ascending Venus can be seen 3.1° below descending Jupiter as they quickly approach each other, heading for a very close encounter on Aug. 27th."
At closest approach on Saturday evening, 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.
As easy as this is to see in the southern hemisphere, it will be difficult to see on the other side of the equator. In the northern hemisphere, the planets hug the horizon at sunset, barely visible in the bright orange glow of early twilight. Northerners, monitor the photo gallery to see what you are missing.
Realtime Space Weather Photo Gallery
COSMIC RAYS AND CLOUDS--NEW RESULTS: The connection between cosmic rays and clouds has long been controversial. Some researchers hold that cosmic rays hitting Earth's atmosphere create aerosols which, in turn, seed clouds. This could make cosmic rays an important player in weather and climate. Other researchers, however, are less convinced. Although some laboratory experiments support the idea that cosmic rays help seed clouds, skeptics say the effect is too small to substantially affect the cloudiness of our planet or to avert the course of climate change.
A new study just published in the Aug. 19th issue of Journal of Geophysical Research: Space Physics comes down in favor of cosmic rays. A team of scientists from the Technical University of Denmark (DTU) and the Hebrew University of Jerusalem has linked sudden decreases in cosmic rays (called "Forbush Decreases") to changes in Earth's cloud cover.
Forbush Decreases occur when solar storms called "coronal mass ejections (CMEs)" sweep past Earth. Magnetic fields in CMEs deflect cosmic rays and, essentially, sweep some of the cosmic rays away from our planet. The research team led by Jacob Svensmark of DTU identified the strongest 26 Forbush Decreases between 1987 and 2007, and looked at ground-based+satellite records of cloud cover to see what happened. In a press release, their conclusions were summarized as follows: "[Strong Forbush Decreases] cause a reduction in cloud fraction of about 2 percent corresponding to roughly a billion tonnes of liquid water disappearing from the atmosphere."
If true, that's amazing. It would also underscore the importance of measuring cosmic rays in the atmosphere. Recent balloon flights by Spaceweather.com and Earth to Sky Calculus show that cosmic rays are intensifying. Cloudy days, anyone? Stay tuned for updates.
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. 26, 2016, the network reported 27 fireballs.
(24 sporadics, 2 Southern delta Aquariids, 1 Northern delta Aquariid)
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 26, 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.
| ||The official U.S. government space weather bureau |
| ||The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| ||Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| ||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 |
| ||a proud supporter of science education and Spaceweather.com |
| ||the underlying science of space weather |
| ||Tobi -- Proud Supporter of Space Education! |
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