The Stars Beckon

Laser Trails and Star Trails

40 minutes of exposure time on the summit of Mauna Kea. Keck II was using the laser adaptive optics system. From left to right are the James Clerk Maxwell Telescope, Subaru, Keck I and II, Caltech Submillimeter Observatory, and NASA Infrared Telescope Facility. — Sean Goebel

(Source: ikenbot)

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Road To Rainbow Galaxy | markg«

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Sun Emits Mid-Level Flare

A burst of solar material leaps off the left side of the sun in what’s known as a prominence eruption. This image combines three images from NASA’s Solar Dynamics Observatory captured on May 3, 2013, at 1:45 pm EDT, just as an M-class solar flare from the same region was subsiding. The images include light from the 131-, 171- and 304-angstrom wavelengths.

The sun emitted a mid-level solar flare, peaking at 1:32 pm EDT on May 3, 2013. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth’s atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel. This disrupts the radio signals for as long as the flare is ongoing, and the radio blackout for this flare has already subsided.

This flare is classified as an M5.7-class flare. M-class flares are the weakest flares that can still cause some space weather effects near Earth. Increased numbers of flares are quite common at the moment, as the sun’s normal 11-year activity cycle is ramping up toward solar maximum, which is expected in late 2013.

Credit: NASA/SDO/AIA

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Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station, on October 4, 2012. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module’s robotic arm on October 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment.

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Kathryn Hire installing the Cupola on STS-130. (x)

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The Curious Channel 37 — Must-see TV For Radio Astronomy

Thanks to Channel 37, radio astronomers keep tabs on everything from the Sun to pulsars to the lonely spaces between the stars. This particular frequency, squarely in the middle of the UHF TV broadcast band, has been reserved for radio astronomy since 1963, when astronomers successfully lobbied the FCC to keep it TV-free.

Back then UHF TV stations were few and far between. Now there are hundreds, and I’m sure a few would love to soak up that last sliver of spectrum. Sorry Charley, the moratorium is still in effect to this day. Not only that, but it’s observed in most countries across the world.

So what’s so important about Channel 37? Well, it’s smack in the middle of two other important bands already allocated to radio astronomy – 410 Megahertz (MHz) and 1.4 Gigahertz (Gz). Without it, radio astronomers would lose a key window in an otherwise continuous radio view of the sky. Imagine a 3-panel bay window with the middle pane painted black. Who wants THAT?

Channel 37 occupies a band spanning from 608-614 MHz. A word about Hertz. Radio waves are a form of light just like the colors we see in the rainbow or the X-rays doctors use to probe our bones. Only difference is, our eyes aren’t sensitive to them. But we can build instruments like X-ray machines and radio telescopes to “see” them for us.

Every color of light has a characteristic wavelength and frequency. Wavelength is the distance between successive crests in a light wave which you can visualize as a wave moving across a pond. Waves of visible light range from one-millionth to one-billionth of a meter, comparable to the size of a virus or DNA molecule.

X-rays crests are jammed together even more tightly – one X-ray is only as big as an small atom. Radio waves fill out the opposite end of the spectrum with wavelengths ranging from baseball-sized to more than 600 miles (1000 km) long.

The frequency of a light wave is measured by how many crests pass a given point over a given time. If only one crest passes that point every second, the light beam has a frequency of 1 cycle per second or 1 Hertz. Blue light has a wavelength of 462 billionths of a meter and frequency of 645 trillion Hertz (645 Terahertz).

The higher the frequency, the greater the energy the light carries. X-rays have frequencies starting around 30 quadrillion Hertz (30 petahertz or 30 PHz), enough juice to damage body cells if you get too much exposure. Even ultraviolet light has power to burn skin as many of us who’ve spent time outdoors in summer without sunscreen are aware.

Radio waves are the gentle giants of the electromagnetic spectrum. Their enormous wavelengths mean low frequencies. Channel 37 radio waves have more modest frequencies of around 600 million Hertz (MHz), while the longest radio waves deliver crests almost twice the width of Lake Superior at a rate of 3 to 300 Hertz.

If Channel 37 were ever lost to TV, the gap would mean a loss of information about the distribution of cosmic rays in the Milky Way galaxy and rapidly rotating stars called pulsars created in the wake of supernovae. Closer to home, observations in the 608-614 MHz band allow astronomers track bursts of radio energy produced by particles blasted out by solar flares traveling through the sun’s outer atmosphere. Some of these can have powerful effects on Earth. No wonder astronomers want to keep this slice of the electromagnetic spectrum quiet. For more details on how useful this sliver is to radio astronomy, click HERE.

Just as optical astronomers seek the darkest sites for their telescopes to probe the most remote corners of the universe, so too does radio astronomy need slices of silence to listen to the faintest whispers of the cosmos.

image 1: The Very Large Array, one of the world’s premier astronomical radio observatories, consists of 27 radio antennas in a Y-shaped configuration 50 miles west of Socorro, New Mexico. Each antenna is 82 feet (25 m) in diameter. The data from the antennas is combined electronically to give the resolution of an antenna 22 miles (36 km) across. credit: NRAO/AUI and NRAO

image 2: Channel 37, a slice of the radio spectrum from 608 and 614 Megahertz (MHz) reserved for radio astronomy, sits in the middle of the UHF TV band. Click to see the full spectrum. credit: US Dept. of Commerce

image 3: The visible colors, infrared, radio, X-rays and gamma rays are all forms of light and comprise the electromagnetic spectrum. Here you can compare their wavelengths with familiar objects and see how their frequencies (bottom numbers) increase with decreasing wavelength. credit: ESA

image 4: Diagram showing what how Earth’s atmosphere allows visible light, a portion of infrared and radio light to reach the ground from outer space but filters shorter-wavelength, more dangerous forms of light like X-rays and gamma rays. To study the cosmos in these varieties of light, orbiting telescopes are required.

image 5: If our eyes could see radio light, this is what the sky would look like. What appear to be stars are actually distant galaxies glowing brightly with energy radiated as matter gets sucked down black holes in the cores. The wispy arcs and shells are the remnants of exploding supernovae. Since air molecules don’t scatter radio waves like they do visible light to create a blue sky, the sky would be dark even on a sunny day. credit: National Science Foundation

image 6: The sun as it would look in the radio portion of the spectrum at a frequency of 1.4 gigahertz (GHz). credit: National Radio Astronomy Observatory (NRAO/AUI)

Stay Curious! Watch: First Contact: Carl Sagan On Radio Astronomy

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Search for E.T. Should Extend Beyond ‘Alien Earths,’ Astronomer Says | Space.com

Scientists searching for signs of life beyond our solar system should keep an open mind, for planets very different than Earth may well be habitable, a prominent researcher says.

While it may seem natural to zero in on “alien Earths,” such a narrow focus would exclude many potentially life-supporting exoplanets, whose diversity continues to astound astronomers, says Sara Seager of MIT.

And researchers can’t afford to be so picky, she adds, since they’ll be able to get in-depth looks at just a handful of alien worlds for the foreseeable future.

“The number of planets that we’re going to be able to see in our lifetime — and look at their atmospheres for signs of life— is so small that we’re forced to be open-minded,” Seager told SPACE.com.

[Read more]