Stellar Danger Zones, Planets Not Welcome

•August 2, 2008 • 1 Comment

Astronomers have determined how far away from its hot stellar neighbors a star must be if a swirling disk of dust around it is to stand a chance of forming planets.

Using NASA’s Spitzer Space Telescope, scientists created the first maps of so-called planetary “danger-zones,” areas where winds and radiation from super-hot stars can strip younger, cooler stars like our Sun of their planet-forming materials.

The findings suggest that so long as cool stars lie beyond about 1.6 light years, or nearly 10 trillion miles, of any hot stars, they can form planets.

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Earth’s Cries Recorded in Space

•August 2, 2008 • 8 Comments

Earth emits an ear-piercing series of chirps and whistles that could be heard by any aliens who might be listening, astronomers have discovered.

The sound is awful, a new recording from space reveals.

Scientists have known about the radiation since the 1970s. It is created high above the planet, where charged particles from the solar wind collide with Earth’s magnetic field. It is related to the phenomenon that generates the colorful aurora, or Northern Lights.

The radio waves are blocked by the ionosphere, a charged layer atop our atmosphere, so they do not reach Earth. That’s good, because the out-of-this-world radio waves are 10,000 times stronger than even the strongest military signal, the researchers said, and they would overwhelm all radio stations on the planet.

Theorists had long figured the radio waves, which were not well studied, oozed into space in an ever-widening cone, like light from a torch.

But new data from the European Space Agency’s Cluster mission, a group of four high-flying satellites, reveals the bursts of radio waves head off to the cosmos in beam-like fashion, instead.

This means they’re more detectable to anyone who might be listening.

The Auroral Kilometric Radiation (AKR), as it is called, is beamed out in a narrow plane, as if someone had put a mask over a torch and left a slit for the radiation to escape.

This flat beam could be detected by aliens who’ve figured this process out, the researchers say. The knowledge could also be used by Earth’s astronomers to detect planets around other stars, if they can build a new radio telescope big enough for the search. They could also learn more about Jupiter and Saturn by studying AKR, which should emit from the auroral activity on those worlds, too.

“Whenever you have aurora, you get AKR,” said Robert Mutel, a University of Iowa researcher involved in the work.

The AKR bursts — Mutel and colleagues studied 12,000 of them — originate in spots the size of a large city a few thousand miles above Earth and above the region where the Northern Lights form.

“We can now determine exactly where the emission is coming from,” Mutel said.

Our planet is also known to hum, a mysterious low-frequency sound thought to be caused by the churning ocean or the roiling atmosphere.

The Roar of the Aurora

•August 2, 2008 • 1 Comment

It’s the mother of all earthly radio transmissions, a broadcast that’s been on the air for billions of years. However, and despite the long run, it’s one radio program that you’ll probably give a pass: it sounds like Fast-Finger Freddie twisting the shortwave dial at a few hundred RPM.

This cacophony of radio static from Earth is known as Auroral Kilometric Radiation (so-called because the wavelength of the emission is typically kilometers long). AKR is generated when fast-moving particles boil off the sun, gush into space, and then get manhandled by Earth’s magnetic field. The same circumstance accounts for the aurora borealis — those ghostly celestial displays that quietly amuse bored Canadians and insomnious polar bears.

But AKR, which has been in the news lately, has caught the notice of many space fans. They see it as just the sort of signal that could tip off aliens about Earth’s existence, a kind of radio fingerprint of our world. And if that’s possible, then perhaps we might use our radio telescopes to detect the AKR billowing off ET’s planet.

Adding to the allure, AKR is no pipsqueak signal: The power involved is measured in millions of watts.

So, could aliens be tuning into this, the most powerful radio transmitter on Earth?

In principle they could, but in practice this would be tougher than a three-dollar steak. One problem for any extraterrestrial listeners is confusion with other solar system emitters. Both the sun and Jupiter — each of which have magnetic fields many thousands of times stronger than Earth’s — belch more powerful natural signals into space than we do. (Mercury, Saturn, Uranus and Neptune are also members of this cosmic chorus.) The aliens would have to wield highly directional antenna arrays to pick out Earth from this noisy crowd.

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How The First Stars In The Universe Came Into Existence

•August 2, 2008 • Leave a Comment

Researchers believe that our universe began with the Big Bang about 13 billion years ago, and that soon after that event, matter began to form as small dust grains and gases.

The first primordial stars began as tiny seeds that grew rapidly into stars one hundred times the mass of our own Sun. Seen here in this artist’s impression, swirling clouds of hydrogen and helium gasses are illuminated by the first starlight to shine in the Universe. In the lower portion of the artwork, a supernova explodes, ejecting heavier elements that will someday be incorporated into new stars and planets. (Credit: Image courtesy of David A. Aguilar (CfA) via Science/AAAS)

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Oil rebounds from 3-day slide

•July 18, 2008 • Leave a Comment

Crude futures climb above $130 a barrel. Recent decline has taken $16 a barrel off prices.

Oil climbed back above $130 a barrel Friday in Asia as news of an output cut in Nigeria helped to halt the steady decline in prices that began three days ago.

Eni SpA said Thursday that it had shut down pipelines carrying 47,000 barrels of oil a day after a “sudden drop of pressure.”

A Nigerian military official said an explosion had damaged an Eni pipeline in the country’s oil-rich south early Thursday, although he didn’t know how severely.

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Summer Arctic Sea Ice Expected To Be Among Lowest On Record

•July 18, 2008 • Leave a Comment

The ice cover in the Arctic Ocean at the end of summer 2008 will lie, with almost 100 per cent probability, below that of the year 2005 — the year with the second lowest sea ice extent ever measured. Chances of an equally low value as in the extreme conditions of the year 2007 lie around eight per cent. Climate scientists from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association come to this conclusion in a recent model calculation.

Simulated minimum sea-ice extent in 2008 when forced with atmospheric data from each year between 1988 and 2007 from the initial state of June 27, 2008. Model derived ice extents have been adjusted with a constant offset to account for discrepancies with satellite-derived ice extents. The thick black horizontal line displays the yearly minimum ice extent from 2007. (Credit: Alfred Wegener Institute)

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Volcanic Eruptions Wiped Out Ocean Life 94 Million Years Ago

•July 18, 2008 • Leave a Comment

The underwater volcano Kavachi during an eruption in June of 2000. (Credit: Photos by Dr. Brent McInnes, CSIRO; courtesy of NOAA)

Undersea volcanic activity triggered a mass extinction of marine life and buried a thick mat of organic matter on the sea floor about 93 million years ago, which became a major source of oil, according to a new study.

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