Thursday, December 30, 2010

Forecasters Keep Eye on Looming Solar Max

The coming year will be an important one for space weather as the Sun pulls out of a trough of low activity and heads into a long-awaited and possibly destructive period of turbulence. Many people may be surprised to learn that the Sun, rather than burn with faultless consistency, goes through moments of calm and tempest.

But two centuries of observing sunspots -- dark, relatively cool marks on the solar face linked to mighty magnetic forces -- have revealed that our star follows a roughly 11-year cycle of behaviour. The latest cycle began in 1996 and for reasons which are unclear has taken longer than expected to end. "The latest prediction looks at around midway 2013 as being the maximum phase of the solar cycle," said Joe Kunches of the Space Weather Prediction Center at the US National Oceanic and Atmospheric Administration (NOAA).

Monday, December 20, 2010

Total Lunar Eclipse Monday Night

For a few hours on the night of Dec. 20 to Dec. 21, the attention of tens of millions of people will be drawn skyward, where the mottled, coppery globe of our moon will hang completely immersed in the long, tapering cone of shadow cast out into space by our Earth. If the weather is clear, favorably placed skywatchers will have a view of one of nature's most beautiful spectacles: a total eclipse of the moon.

Unlike a total eclipse of the sun, which is only visible to those in the path of totality, eclipses of the moon can usually be observed from one's own backyard. The passage of the moon through the Earth's shadow is equally visible from all places within the hemisphere where the moon is above the horizon.

Wednesday, December 15, 2010

Possible Ice Volcano Spied on Saturn Moon

Scientists said they have found the best evidence yet of ice volcanoes on Saturn's giant moon Titan. Unlike volcanoes on Earth, such a volcano on Titan may spew ice and hydrocarbons instead of molten lava. "We finally have some proof that Titan is an active world," said geophysicist Randolph Kirk of the U.S. Geological Survey, who presented the findings.

The latest evidence comes from the international Cassini spacecraft, which spied two peaks over 3,000 feet tall and what looked like old volcanic flows. Researchers said the landforms resembled Mount Etna in Italy or Laki volcano in Iceland. There's no sign of volcanic activity on Titan, though scientists are keeping watch.

Venus Miss Is Setback for Japanese Program

Researchers and engineers working with Japan's Akatsuki spacecraft were spared the worst-case scenario on 6 December. Although Akatsuki failed to make contact for more than an hour after the scheduled engine burn that was to place it in orbit around Venus, it did eventually call home. But the news was not promising. Not only had Akatsuki been tumbling out of control for a period of time, it had failed to enter orbit. It will now have to circle the Sun for six years before it gets a second chance.

The failure derails an ambitious program of research into Venus's atmosphere, and marks the third time that the Japan Aerospace Exploration Agency (JAXA) has battled mechanical problems on a mission to another Solar System body. In 1998, a faulty valve caused a loss of fuel on JAXA's Nozomi spacecraft, which ultimately prevented it from orbiting Mars. And the Hayabusa probe, which returned a minute quantity of asteroidal material to Earth this year, experienced a variety of near-fatal problems.

Tuesday, December 14, 2010

Voyager Near Solar System's Edge

Voyager 1, the most distant spacecraft from Earth, has reached a new milestone in its quest to leave the Solar System. Now 10.8 billion miles) from home, the veteran probe has detected a distinct change in the flow of particles that surround it. These particles, which emanate from the Sun, are no longer travelling outwards but are moving sideways.

It means Voyager must be very close to making the jump to interstellar space - the space between the stars. The newly reported observation comes from Voyager 1's Low-Energy Charged Particle Instrument, which has been monitoring the velocity of the solar wind. This stream of charged particles forms a bubble around our Solar System known as the heliosphere. The wind travels at "supersonic" speed until it crosses a shockwave called the termination shock. At this point, the wind then slows dramatically and heats up in a region termed the heliosheath. Voyager has determined the velocity of the wind at its location has now slowed to zero.

Monday, December 13, 2010

Saturn's Rings: Leftovers from a Cosmic Murder?

One of the solar system's most evocative mysteries—the origin of Saturn's rings—may be a case of cosmic murder, new research suggests. The victim: an unnamed moon of Saturn that disappeared about 4.5 billion years ago. The suspect: a disk of hydrogen gas that once surrounded Saturn when its dozens of moons were forming, but has now fled the crime scene. The cause of death: A forced plunge into Saturn. And those spectacular and colorful rings are the only evidence left.

As the doomed moon made its death spiral, Saturn robbed its outer layer of ice, which then formed rings, according to a new theory published online Sunday in the journal Nature. A large disk of hydrogen gas circled Saturn and that helped both create and destroy moons. Large inner moons probably made regular plunges into the planet, pulled by the disk of gas. These death spirals took about 10,000 years and the key to understanding the rings' origins is what happened to them during that time. According to Canup's computer model, Saturn stripped the ice away from a huge moon while it was far enough from the planet that the ice would be trapped in a ring.

Geminid Meteor Shower Expects Dazzling Display

Stargazers who stay up late tonight will see what NASA describes as the best meteor shower of the year. The Geminid meteor shower is comprised of debris from 3200 Phaethon, an extinct comet that was once thought to be an asteroid, The Associated Press reported. When the earth passes through this debris stream, the meteors, or shooting stars, seem to fall from the Gemini constellation.

"Of all the debris streams Earth passes through every year, the Geminids' is by far the most massive," astronomer Bill Cooke said. "When we add up the amount of dust in the Geminid stream, it outweighs other streams by factors of 5 to 500." According to PC Magazine, the 2010 Geminids promises to fill the night sky with 50 to 120 shooting star sightings per hour. Although the shower will be visible from almost any point on Earth until Dec. 16, the best views will be seen in the Northern Hemisphere between midnight and sunrise early Tuesday.

Tuesday, December 7, 2010

Dancing Stars Turn on the Red Light

For the first time, astronomers have watched the spiralling dance performed by two stars merging into a single star. The observations, taken between 2001 and 2008, suggest a solution to the vexed problem of how rare "red novae" form. Most novae are blue and occur when material on a white dwarf star explodes. But what causes red novae has been a mystery.

In September 2008, the red nova V1309 Scorpii appeared in the Milky Way. Fortunately, it was positioned in a part of the sky being watched by the Optical Gravitational Lensing Experiment (OGLE), a Polish-run programme using data from a telescope at the Las Campanas Observatory in Chile to search for signs of dark matter and planets. As a result, the team had inadvertently captured the process that sparked the red nova.

Saturn's Strange Propellers Are Clues to Formation

For six years, the Cassini spacecraft has been touring Saturn and its magnificent rings. Unlike previous spacecraft, which have snatched a passing glimpse of the planet on their way to the edges of the solar system, Cassini has beamed back stunningly detailed images year after year. Among the most striking are structures shaped like aircraft propellers. They are the wakes created by unseen moons as they plough through the icy rubble orbiting around Saturn. Dozens of propellers have been spotted in the A-ring, a band 14,000 kilometres wide and only 10 metres deep.

The moons themselves are too small even for Cassini to see directly because they are only a few kilometres to a few hundred metres across. In contrast, their propeller-shaped wakes can be thousands of kilometres long, and some have now been observed orbiting Saturn for several years. They form as a result of a moon's gravity tugging on the surrounding material. The debris inside its orbit, being closer to Saturn, is moving faster, and the perturbation therefore quickly overtakes the moon, creating a long, thin wake ahead of it. This is the leading blade of the propeller. Meanwhile, the material outside the moon's orbit is moving more slowly, creating the trailing blade.

Japan Probe Reaches Venus but Shuts Down

A Japanese space probe sent to the thick clouds of Venus shut itself down, and its future looks as hazy as the planet it was built to study. The probe, called Akatsuki, which means "dawn," reached Venus on Tuesday to orbit Earth's neighbor on a two-year mission. But communication problems left scientists in the dark about whether it was successfully in orbit.

An American scientist on the probe's research team said the probe shut itself partially down and is in safe mode. That means it is sending back signals indicating it is alive, but not transmitting any data. At first, controllers back on Earth lost contact with the probe and got modulating signals indicating that spaceship may be wobbling a bit. But after a few hours, engineers at NASA and the Japanese space agency, JAXA, were able to lock on the probe's signal and found it shut itself down to protect itself, Limaye said.

Monday, December 6, 2010

Stripes Are Back in Season on Jupiter

New NASA images support findings that one of Jupiter's stripes that "disappeared" last spring is now showing signs of a comeback. These new observations will help scientists better understand the interaction between Jupiter's winds and cloud chemistry.

Earlier this year, amateur astronomers noticed that a longstanding dark-brown stripe, known as the South Equatorial Belt, just south of Jupiter's equator, had turned white. In early November, amateur astronomer Christopher Go of Cebu City, Philippines, saw an unusually bright spot in the white area that was once the dark stripe. This phenomenon piqued the interest of scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and elsewhere.

Wednesday, December 1, 2010

Planet System May Be Most Populated Yet Found

A densely packed set of planets around a sunlike star located 127 light-years from Earth in the southern constellation Hydrus may be the closest match yet found to our solar system, at least by the numbers, astronomers say. At least five Neptune-like planets have been spotted orbiting the star HD 10180—and there's evidence of two more worlds, one farther from the star and another closer in.

If the latter observations can be confirmed, the innermost planet may hold the record for the lowest-mass extrasolar planet, or exoplanet, seen to date. "We remain cautious about the existence of the innermost and outermost planets," said study lead author Christophe Lovis, an astronomer with the Observatory of Geneva in Switzerland. "But I am confident that at least one of them will be definitively confirmed soon, thus making this system the most populous known so far."