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WAITING FOR IMPACT: Four days after it left the sun, the CME of Sept. 30th has still not hit Earth's magnetic field. This could mean that the cloud has missed our planet. NOAA forecasters say the tardy CME might yet arrive during the late hours of Oct. 4th, with a 65% chance of geomagnetic storms if and when it hits. Aurora alerts: text or voice
'WATER-BASED LAVA' ON PLUTO'S MOON? Pluto's moon Charon is so large that some astronomers have called Pluto and Charon a "double-planet." Could Charon be just as interesting as Pluto? Images just received from NASA's New Horizons spacecraft suggest that it is. When New Horizons hurtled past the Pluto-Charon system last July, it saw a canyon system stretching more than 1,000 miles across Charon's icy face. Four times as long as the Grand Canyon, and twice as deep in places, the structure marks a titanic geological upheaval in Charon's past:
"It looks like the entire crust of Charon has been split open," says John Spencer, a member of the New Horizons Science Team from the Southwest Research Institute. "With respect to its size relative to Charon, this feature is much like the vast Valles Marineris canyon system on Mars."
The pictures also show plains south of the Charon's canyon with fewer large craters than regions to the north. This means the southern plains are younger. The smoothness of the plains, as well as their grooves and faint ridges, are clear signs of wide-scale resurfacing:
One possibility for the smooth surface is a kind of cold volcanic activity, called cryovolcanism. "The team is discussing the possibility that an internal water ocean could have frozen long ago, and the resulting volume change could have led to Charon cracking open, allowing water-based lavas to reach the surface," says Paul Schenk, a New Horizons team member from the Lunar and Planetary Institute in Houston.
More images and data are in the offing as New Horizons continues to transmit data, stored on its digital recorders, over the next year. As that happens, "I predict Charon's story will become even more amazing!" says mission Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory. Stay tuned.
Realtime Space Weather Photo Gallery
COSMIC RAYS DURING THE LUNAR ECLIPSE: On the evening of Sept. 27th, Spaceweather.com and the students of Earth to Sky Calculus conducted a routine flight of their cosmic ray payload to the stratosphere. Routine, that is, except for one thing: the balloon flew at night during a lunar eclipse. One of the goals of the flight was to compare radiation levels at night to those recorded during the day. Here are the data they recorded:
Compare this plot of radiation vs. altitude to a similar plot recorded in broad daylight only a few days earlier. They are almost identical. Radiation levels in the stratosphere matched at the 1% level. Radiation levels at aviation altitudes (where planes fly) agreed within about 3%. Night and day were the same.
This simple experiment highlights something that is already well known to researchers. Cosmic rays in Earth's atmosphere come mainly from deep space. They are accelerated toward Earth by supernovas, colliding neutron stars, and other violent events in the Milky Way. Flying at night is no safeguard against these energetic particles because they are everpresent, coming at us from all directions, day and night.
HEY THANKS (and Happy Birthday): The lunar eclipse flight was sponsored by Spaceweather.com reader JR Biggs, whose donation of $500 paid for the supplies neccesary to get the balloon off the ground. To say "thank you" for his contribution, we flew a birthday card for his daughter to the edge of space:
Happy Birthday to Autumn! She will be watching a complete video of the flight when she turns 4 on Oct. 10th.
Readers, if you would like to support a research flight and send your birthday card, business logo, or other photo along for the ride, it only costs $500. Contact Dr. Tony Phillips to make arrangements.
Realtime Eclipse Photo Gallery
Realtime Aurora Photo Gallery
Realtime Sprite Photo Gallery
| ||Cosmic Rays in the Atmosphere |
These measurements are based on space weather balloon flights, described below.
|Situation Report -- Oct. 3, 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: 414 uRad/hr |
|Sept. 12: 409 uRad/hr |
|Sept. 23: 412 uRad/hr |
|Sept. 25: 416 uRad/hr |
|Sept. 27: 413 uRad/hr |
Introduction: Once a week, and sometimes more often, Spaceweather.com and the students of Earth to Sky Calculus fly "space weather balloons" to the stratosphere. These balloons are equipped with radiation sensors that detect cosmic rays, a form of space weather important to people on Earth. Cosmic rays can alter the chemistry of the upper atmosphere, seed clouds, spark exotic forms of lightning, and penetrate commercial airplanes. This last point is of special interest to the traveling public. 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. From now on we will present the results of our regular weekly balloon flights in this section of our web site. Here is the radiation profile from our latest flight:
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 nearly 100x 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 Sept. 27th measurements, a plane flying at 45,000 feet is exposed to 288 uRads/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in 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.
Stay tuned for improvements to this section in the days and weeks ahead as we develop a glossary and better plain language strategies for communicating this information. Suggestions are welcomed.
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. 4, 2015, the network reported 5 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 October 4, 2015 there were 1612 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.
| ||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 |
| ||the underlying science of space weather |
| ||Web-based high school science course with free enrollment |