"The surface of the Earth is the shore of the cosmic ocean... Recently, we've managed to wade a little way out, and the water seems inviting." - Carl Sagan
Hungarian rhapsody stars Moon and Jupiter
As seen on the National Geographic News a father and daughter contemplate a starry meeting of Jupiter and the moon, over Lake Balaton in Hungary, also known as the Hungarian Sea.
Image credit & copyright: Tamas Ladanyi
ALMA finds double star with weird and wild planet-forming discs
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found wildly misaligned planet-forming gas discs around the two young stars in the binary system HK Tauri. These new ALMA observations provide the clearest picture ever of protoplanetary discs in a double star. The new result also helps to explain why so many exoplanets — unlike the planets in the Solar System — came to have strange, eccentric or inclined orbits.
Unlike our solitary Sun, most stars form in binary pairs — two stars that are in orbit around each other. Binary stars are very common, but they pose a number of questions, including how and where planets form in such complex environments.
“ALMA has now given us the best view yet of a binary star system sporting protoplanetary discs — and we find that the discs are mutually misaligned!” said Eric Jensen, an astronomer at Swarthmore College in Pennsylvania, USA.
The two stars in the HK Tauri system, which is located about 450 light-years from Earth in the constellation of Taurus (The Bull), are less than five million years old and separated by about 58 billion kilometres — this is 13 times the distance of Neptune from the Sun.
The fainter star, HK Tauri B, is surrounded by an edge-on protoplanetary disc that blocks the starlight. Because the glare of the star is suppressed, astronomers can easily get a good view of the disc by observing in visible light, or at near-infrared wavelengths.
The companion star, HK Tauri A, also has a disc, but in this case it does not block out the starlight. As a result the disc cannot be seen in visible light because its faint glow is swamped by the dazzling brightness of the star. But it does shine brightly in millimetre-wavelength light, which ALMA can readily detect.
Using ALMA, the team were not only able to see the disc around HK Tauri A, but they could also measure its rotation for the first time. This clearer picture enabled the astronomers to calculate that the two discs are out of alignment with each other by at least 60 degrees. So rather than being in the same plane as the orbits of the two stars at least one of the discs must be significantly misaligned.
Image credit: R. Hurt (NASA/JPL-Caltech/IPAC)
M31: The Andromeda Galaxy
Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda’s image are actually stars in our Galaxy that are well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier’s list of diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there. Although visible without aid, the above image of M31 was taken with a standard camera through a small telescope. Much about M31 remains unknown, including how it acquired its unusual double-peaked center.
Image credit & copyright: Jacob Bers (Bersonic)
Cassini spacecraft reveals 101 geysers and more on icy Saturn moon
Scientists using mission data from NASA’s Cassini spacecraft have identified 101 distinct geysers erupting on Saturn’s icy moon Enceladus. Their analysis suggests it is possible for liquid water to reach from the moon’s underground sea all the way to its surface.
Over a period of almost seven years, Cassini’s cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent “tiger stripe” fractures and the geysers of tiny icy particles and water vapor first sighted there nearly 10 years ago. The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots. These relationships pointed the way to the geysers’ origin.
After the first sighting of the geysers in 2005, scientists suspected that repeated flexing of Enceladus by Saturn’s tides as the moon orbits the planet had something to do with their behavior. One suggestion included the back-and-forth rubbing of opposing walls of the fractures generating frictional heat that turned ice into geyser-forming vapor and liquid.
Alternate views held that the opening and closing of the fractures allowed water vapor from below to reach the surface. Before this new study, it was not clear which process was the dominating influence. Nor was it certain whether excess heat emitted by Enceladus was everywhere correlated with geyser activity.
To determine the surface locations of the geysers, researchers employed the same process of triangulation used historically to survey geological features on Earth, such as mountains. When the researchers compared the geysers’ locations with low-resolution maps of thermal emission, it became apparent the greatest geyser activity coincided with the greatest thermal radiation. Comparisons between the geysers and tidal stresses revealed similar connections. However, these correlations alone were insufficient to answer the question, “What produces what?”
The answer to this mystery came from comparison of the survey results with high-resolution data collected in 2010 by Cassini’s heat-sensing instruments. Individual geysers were found to coincide with small-scale hot spots, only a few dozen feet (or tens of meters) across, which were too small to be produced by frictional heating, but the right size to be the result of condensation of vapor on the near-surface walls of the fractures. This immediately implicated the hot spots as the signature of the geysering process.
"Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper. "It also told us the geysers are not a near-surface phenomenon, but have much deeper roots."
Thanks to recent analysis of Cassini gravity data, the researchers concluded the only plausible source of the material forming the geysers is the sea now known to exist beneath the ice shell. They also found that narrow pathways through the ice shell can remain open from the sea all the way to the surface, if filled with liquid water.
NASA long-lived Mars Opportunity rover sets off-world driving record
NASA’s Opportunity Mars rover, which landed on the Red Planet in 2004, now holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving. The previous record was held by the Soviet Union’s Lunokhod 2 rover.
"Opportunity has driven farther than any other wheeled vehicle on another world," said Mars Exploration Rover Project Manager John Callas, of NASA’s Jet Propulsion Laboratory in Pasadena, California. "This is so remarkable considering Opportunity was intended to drive about one kilometer and was never designed for distance. But what is really important is not how many miles the rover has racked up, but how much exploration and discovery we have accomplished over that distance."
A drive of 157 feet (48 meters) on July 27 put Opportunity’s total odometry at 25.01 miles (40.25 kilometers). This month’s driving brought the rover southward along the western rim of Endeavour Crater. The rover had driven more than 20 miles (32 kilometers) before arriving at Endeavour Crater in 2011, where it has examined outcrops on the crater’s rim containing clay and sulfate-bearing minerals. The sites are yielding evidence of ancient environments with less acidic water than those examined at Opportunity’s landing site.
If the rover can continue to operate the distance of a marathon — 26.2 miles (about 42.2 kilometers) — it will approach the next major investigation site mission scientists have dubbed “Marathon Valley.” Observations from spacecraft orbiting Mars suggest several clay minerals are exposed close together at this valley site, surrounded by steep slopes where the relationships among different layers may be evident.
The Russian Lunokhod 2 rover, a successor to the first Lunokhod mission in 1970, landed on Earth’s moon on Jan. 15, 1973, where it drove about 24.2 miles (39 kilometers) in less than five months, according to calculations recently made using images from NASA’s Lunar Reconnaissance Orbiter (LRO) cameras that reveal Lunokhod 2’s tracks.
Observing alert – Delta Aquarid meteor shower peaks this week
The Horsehead nebula from blue to infrared
One of the most identifiable nebulae in the sky, the Horsehead Nebula in Orion, is part of a large, dark, molecular cloud. Also known as Barnard 33, the unusual shape was first discovered on aphotographic plate in the late 1800s. The red glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick dust, although the lower part of the Horsehead’s neck casts a shadow to the left. Streams of gas leaving the nebula are funneled by a strong magnetic field. Bright spots in the Horsehead Nebula’s base are young stars just in the process of forming. Light takes about 1,500 years to reach us from the Horsehead Nebula. The above image is a digital combination of images taken in blue, green, red, and hydrogen-alpha light from the Argentina, and an image taken in infrared light by the orbiting Hubble Space Telescope.
Image credit & copyright: Optical: Aldo Mottino & Carlos Colazo, OAC, Córdoba; Infrared: Hubble Legacy Archive
Comet Jacques makes a ‘questionable’ appearance
NGC 253: dusty island universe
Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. First swept up in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, tendrils of dust seem to be rising from a galactic disk laced with young star clusters and star forming regions in this sharp color image. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massives black hole near the galaxy’s center.
Image credit & copyright: László Francsics
Zayd, 23, was on the run.
He had to get to her first—
There was no time to stop now—
Lest they found Chie and did the worst.
The young cadet with nothing
But a communicator on his ear
Rushed through a botanical garden,
Keeping from surveillance in the area.
The trees in the park were quiet,
The looming darkness chilling.
At home there was no plant
But those displayed inside buildings.
The freshly cut grass he stepped on
Was alien to his home moon Cheryl
Where tiles and steel lined the streets,
And organic compounds were peril.
In the sky above he caught a glimpse
Of Cheryl reflecting starlight.
He could have been there at the moment.
Instead Zayd was running for his life.
When Cheryl commanded a meeting
With its host planet Demos f,
Zayd whose father was the envoy
Knew there was little time left.
He offered his military service
To escort the diplomats from the moon,
Who would declare independence
To the planet that would not agree soon.
As he’d predicted they didn’t,
Saying this was not yet the day.
And when one of the men went missing,
The hosts suspected right away.
They learned he’d been in contact
With a young Demosian citizen
For over two years—it wasn’t possible
To assume the couple was innocent.
He couldn’t ask Cheryl for help;
It was common how they operated.
With his knowledge of their nuclear weapons,
They’d have his existence terminated.
His father and the other Cherylese
Must now be at the launch pad,
Preparing for the return to the moon.
No more negotiation to add.
Once his people left this planet,
Demos f would be seeing its last
Days of regular orbit round the star
Before Cheryl had it cast,
Shredding the bond between the two,
The synchronous rotation, the tidal lock.
For the more nature-loving planet,
This would sure be a terrible shock.
Cheryl had been habitable
And harbored life for half a century.
It was an injustice for the moon
To be deemed the planet’s colony.
The people had grown impatient.
Indignation became malice.
Desynchronizing is the only way
That’d gain Cheryl its planetary status.
Next to the park were busy streets:
Shops, pedestrians, souvenirs.
Two Demosian soldiers caught his eyes—
Zayd had to disappear.
He saw an underwater bar
With tons of water and thick glass.
In it Chie’s communicator signals
Could never get through that mass.
Zayd was worried. Where was she?
She’d been getting out of a taxi pod.
The bartender looked, and Zayd
Covered his anxiety with a nod.
The bar was crowded with customers
Enjoying drinks and deafening mutters,
Watching marine animals on one wall
And mermaids’s seductive dance on the other.
Two uniforms entered from the street.
He knew what they came down here for.
Zayd quickly ducked out of view
And slipped out the back door.
Back onto the street he climbed,
Just in time to see Chie his lover,
Who immediately turned around
With fear for what she’d discovered.
Two more soldiers were behind her.
Zayd stopped when he heard his name.
In Chie voice text: “Go back to your ship.
It’s the only sanctuary you can claim.”
“Not going without you,” Zayd yelled
Into the device’s microphone.
He’s just stepped onto another lane
When he realized he wasn’t alone.
Speeding past more people and stalls,
He asked, “Where are you?” No reply.
Another turn and he could lose them—
But the alley was in a spotlight from the sky.
“Where will they put me if I’m taken?”
Crossed his mind when he saw more soldiers
After him, as he ran faster
And felt a sharp pain in his left shoulder.
Following a solar storm that reached the Earth magnetic field, the dancing northern lights or aurora borealis fill the night sky, as captured in this all-sky fisheye view from Yellowknife in the northern Canada, known as one of the world’s best aurora watching destinations. Aurora, which is mostly seen from polar latitudes is produced by the collision of charged particles from Earth’s magnetosphere, mostly electrons but also protons and heavier particles, with atoms and molecules of Earth’s atmosphere (at altitudes above 80 km). The particles originate from the Sun and reach the Earth in the stream of solar wind.
Image credit & copyright: Kwon O Chul
I am a space-wandering craft
Chasing an invisible comet,
Launched for a mock mission
And never reaching its summit.
I am a probe looking for a star
From the time of its commencing,
One that never existed in the sky
Save for gravitational lensing.
I search for evidence of water
On a moon too close to the Sun,
Fantasizing a habitable zone
When in fact there can be none.
I misread a wobbling light
With an exoplanet in mind,
As I’m seeing a binary
While the two stars are aligned.
Undetachable and fettered,
I’m hopelessly entangled—
When I know I’m not Rosetta
Cosmic Crab nebula
The Crab Pulsar, a city-sized, magnetized neutron star spinning 30 times a second, lies at the center of this tantalizing wide-field image of the Crab Nebula. A spectacular picture of one of our Milky Way’s supernova remnants, it combines optical survey data with X-ray data from the orbiting Chandra Observatory. The composite was created as part of a celebration of Chandra’s 15 year long exploration of the high energy cosmos. Like a cosmic dynamo the pulsar powers the X-ray and optical emission from the nebula, accelerating charged particles to extreme energies to produce the jets and rings glowing in X-rays. The innermost ring structure is about a light-year across. With more mass than the Sun and the density of an atomic nucleus, the spinning pulsar is the collapsed core of the massive star that exploded, while the nebula is the expanding remnant of the star’s outer layers. The supernova explosion was witnessed in the year 1054.
Image credit: NASA, Chandra X-ray Observatory, SAO, DSS