Thursday, October 29, 2009

NEW SUN SPOT


The sunspot's large dark core is about the size of Earth, while the entire sunspot group stretches about 50,000 km from end to end.
The behemoth has been crackling with magnetic activity, producing 10 C-class solar flares in the past few days.
That more than triples the number of C-flares (3) previously detected in all of 2009.
According to NOAA forecasters, there is a 5% chance of an even stronger M-class flare during the next 24 hours

Tuesday, October 6, 2009

LUNAR IMPACT

Space Weather News for Oct. 6, 2009
http://spaceweather.com

LUNAR IMPACT: This Friday morning, Oct 9th, at approximately 4:30 am PDT, NASA's LCROSS spacecraft and its Centaur booster rocket will plunge one after another into a shadowed crater near the Moon's south pole.

The spectacular double-impact will be shown live on NASA TV from the point of view of the LCROSS spacecraft.
Meanwhile, impact debris plumes emerging from the crater may be visible through backyard telescopes.
North American sky watchers west of the Mississippi river are favored with darkness and good views of the Moon at the time of impact.
Visit http://spaceweather.com for observing tips and full coverage.

Friday, October 2, 2009

COSMIC RAYS HIT SPACE AGE HIGH


September 29, 2009:

Planning a trip to Mars?

Take plenty of shielding.

According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high.
"In 2009, cosmic ray intensities have increased 19% beyond anything we've seen in the past 50 years," says Richard Mewaldt of Caltech.

"The increase is significant, and it could mean we need to re-think how much radiation shielding astronauts take with them on deep-space missions."The cause of the surge is solar minimum, a deep lull in solar activity that began around 2007 and continues today. Researchers have long known that cosmic rays go up when solar activity goes down. Right now solar activity is as weak as it has been in modern times, setting the stage for what Mewaldt calls "a perfect storm of cosmic rays."
Sign up for EXPRESS SCIENCE NEWS delivery "We're experiencing the deepest solar minimum in nearly a century," says Dean Pesnell of the Goddard Space Flight Center, "so it is no surprise that cosmic rays are at record levels for the Space Age."
Galactic cosmic rays come from outside the solar system. They are subatomic particles--mainly protons but also some heavy nuclei--accelerated to almost light speed by distant supernova explosions. Cosmic rays cause "air showers" of secondary particles when they hit Earth's atmosphere; they pose a health hazard to astronauts; and a single cosmic ray can disable a satellite if it hits an unlucky integrated circuit.
The sun's magnetic field is our first line of defense against these highly-charged, energetic particles. The entire solar system from Mercury to Pluto and beyond is surrounded by a bubble of magnetism called "the heliosphere." It springs from the sun's inner magnetic dynamo and is inflated to gargantuan proportions by the solar wind. When a cosmic ray tries to enter the solar system, it must fight through the heliosphere's outer layers; and if it makes it inside, there is a thicket of magnetic fields waiting to scatter and deflect the intruder.
Right: An artist's concept of the heliosphere, a magnetic bubble that partially protects the solar system from cosmic rays. [larger image]
"At times of low solar activity, this natural shielding is weakened, and more cosmic rays are able to reach the inner solar system," explains Pesnell.
Mewaldt lists three aspects of the current solar minimum that are combining to create the perfect storm:
1. The sun's magnetic field is weak. "There has been a sharp decline in the sun's interplanetary magnetic field down to 4 nT (nanoTesla) from typical values of 6 to 8 nT," he says. "This record-low interplanetary magnetic field undoubtedly contributes to the record-high cosmic ray fluxes." [data]
2. The solar wind is flagging. "Measurements by the Ulysses spacecraft show that solar wind pressure is at a 50-year low," he continues, "so the magnetic bubble that protects the solar system is not being inflated as much as usual." A smaller bubble gives cosmic rays a shorter-shot into the solar system. Once a cosmic ray enters the solar system, it must "swim upstream" against the solar wind. Solar wind speeds have dropped to very low levels in 2008 and 2009, making it easier than usual for a cosmic ray to proceed. [data]
3. The current sheet is flattening. Imagine the sun wearing a ballerina's skirt as wide as the entire solar system with an electrical current flowing along its wavy folds. It's real, and it's called the "heliospheric current sheet," a vast transition zone where the polarity of the sun's magnetic field changes from plus to minus. The current sheet is important because cosmic rays are guided by its folds. Lately, the current sheet has been flattening itself out, allowing cosmic rays more direct access to the inner solar system.
Right: The heliospheric current sheet is shaped like a ballerina's skirt. Image credit: J. R. Jokipii and B. Thomas, Astrophysical Journal 243, 1115, 1981.
"If the flattening continues, we could see cosmic ray fluxes jump all the way to 30% above previous Space Age highs," predicts Mewaldt. [data]
Earth is in no great peril. Our planet's atmosphere and magnetic field provide some defense against the extra cosmic rays. Indeed, we've experienced much worse in the past. Hundreds of years ago, cosmic ray fluxes were at least 200% to 300% higher than anything measured during the Space Age. Researchers know this because when cosmic rays hit the atmosphere, they produce an isotope of beryllium, 10Be, which is preserved in polar ice. By examining ice cores, it is possible to estimate cosmic ray fluxes more than a thousand years into the past. Even with the recent surge, cosmic rays today are much weaker than they have been at times in the past millennium. [data]
"The space era has so far experienced a time of relatively low cosmic ray activity," says Mewaldt. "We may now be returning to levels typical of past centuries."
NASA spacecraft will continue to monitor the situation as solar minimum unfolds. Stay tuned for updates.

BIG (FOOT) DISCOVERY


NASA's MESSENGER spacecraft has made a stunning discovery.
Bigfoot is an extraterrestrial!
His tracks have been found on Mercury
MESSENGER took the picture during a flyby of Mercury on Sept. 29th. The giant paw print was just one of many wonders
MESSENGER's cameras saw imprinted on thousands of square kilometers of previously unseen terrain.
In this case, a cluster of small craters--"toes"--were by chance arranged in an arc above a stack of larger, partially overlapping craters--the "heel." MESSENGER also photographed a happy crater, a double crater, and a crater splash.
Although early results from the flyby are dominated by pictures of craters, the spacecraft also made new measurements of Mercury's
magnetic tornadoes and its comet-like tail.
Mission scientists are still analyzing those data, which are more complicated than crater-snapshots and potentially much more interesting. Stay tuned for updates.

HARVEST MOON


This weekend's full Moon has a special name--The Harvest Moon.

It's the full moon closest to the northern autumnal equinox (Sept. 23).

In years past, farmers depended on the light of the Harvest Moon to gather ripening crops late into the night.

Post-Edison, we appreciate it mainly for its beauty.

Shown above is last year's Harvest Moon, photographed by P-M Hedén of Hedesunda, Sweden. "It was a lovely sight," he recalls.
When the Moon is Harvest-bright, it often lights up ice crystals and water droplets in high clouds, producing luminous haloes and coronas.

Keep an eye out for those beauties, too!