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Jyoti Q Dahiya
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Space | Ceres

Those white spots? There's a rash of them.

From +StarTalk Radio​ via +philippe roux

#space #ceres
 
Ceres’ White Spots Multiply in Latest Dawn Photos
From Universe Today: We don’t know exactly what those mysterious white spots on Ceres are yet, but we’re getting closer to an explanation. Literally. The latest images from the Dawn spacecraft taken a mere 8,400 miles from the dwarf planet Ceres reveal that the pair of  spots are comprised of even more spots. Read more: http://www.universetoday.com/120244/ceres-white-spots-multiply-in-latest-dawn-photos/
Image Credit: Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA / montage by Tom Ruen
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Space | Hot Jupiters and rare Earths

An article to explain the prevalence of hot Jupiters and the rareness of Earthlike planets in the vast universe. I'm not convinced that the prevalence of hot Jupiters is not explained by the non random nature of our sampling process. Still, interesting article.

From +Brian Koberlein​ via +Kam-Yung Soh

(Did you miss the pun in the title? Hee hee hee)

#space #exoplanets
Brian Koberlein originally shared to Our Universe:
 
She's So Unusual

Our solar system follows a clear pattern. Small, rocky planets close to the Sun, large gas planets farther out, and a belt of astroids between them. On a broad level that would seem to make sense. As the Sun formed, the intense energy of its newfound solar wind would tend to push lighter elements such as hydrogen and helium toward the outer solar system, leaving only rocky material behind. It’s tempting then to imagine that most solar systems would follow a similar pattern of close rocky planets and more distant gas giants. But as we’ve discovered more exoplanetary systems, we find that isn’t the case. In fact it increasingly looks like our solar system might be the exception rather than the norm.

When we look at other star systems, we find that a gas planet far from its star is rather unusual. One way to categorize planets is by the energy they receive from their star. Hot planets, such as Mercury and Venus in our solar system, warm (possibly habitable) planets such as Earth and Mars, and cold planets such as Jupiter and beyond. The cut-offs for a particular system depend upon the energy produced by a particular star, but it gives a good idea of near, mid-range and distant planets. In our own solar system, all the gas planets are “cold” planets. But among all confirmed exoplanets, less than 20% of gas planets are cold. The most common type of gas planets are “hot jovians.” These are large, Jupiter-mass planets close to their star.

To be fair, the methods we use to detect exoplanets, such as watching a star dim when a planet passes in front of it (transit method) or measuring the oscillation of a star due to the gravitational tug of an orbiting planet (Doppler method) make it inherently easier to discover large, close planets. But even when this bias is taken into account, it appears that hot jovians are more common than cold ones.

Through computer simulations, we have some ideas as to why that is. In a young system, planets form within a protoplanetary disk, which is basically a fluid of gas and dust. The gas is typically at least partially ionized, so it interacts with the magnetic field of the central star. Because of the dust collisions and clumping, there is also turbulence within the disk. In physics, such a system can be described by magnetohydrodynamics. The equations for such a system are extremely difficult to analyze, but with modern supercomputers we have been able to discover some general trends.

Low mass planets (less than 10 Earth masses) don’t strongly disturb the overall structure of the protoplanetary disk. Their interactions with the disk induce what is known as a spiral density wave within the disk. One wave spirals inward in the leading direction of the planet’s motion, while another wave spirals outward on the trailing edge. Since the drag from the outer spiral is typically larger than the drag from the inner spiral, the planet will tend to move closer to the star fairly quickly. This is known as Type I migration.

For high mass planets (greater than 10 Earth masses, or just below the mass of Uranus and Neptune) not only is a density wave induced, but the planet creates a gap in the protoplanetary disk. You can see this in the right figure above. This means that while there is still a net inward drag, it’s substantially smaller. So the planet would gradually move inward during its formation. This is known as Type II migration. The net effect of both of these dynamics is that planets formed in the disk will tend to move toward the star, and thus close, hot, planets are common.

So why did Jupiter form so far away from the Sun? Trick question: it didn’t.

According to the Grand Tack model, Jupiter likely started to form at about the current distance of Mars. Due to the drag forces of the early solar system it migrated toward the Sun, perhaps as close as the modern orbit of Venus. It was on track to becoming a hot jovian planet were it not for the gravitational interactions of Saturn. The two planets entered a gravitational resonance, where Jupiter would make 3 orbits for every 2 of Saturn. This 2:3 resonance gradually drove the planets outward. Subsequent interactions with Uranus and Neptune drove those planets outward as well.

Jupiter’s journey through the inner solar system explains why our solar system has no hot jovian worlds. It also explains why we have no “super-earths,” when such large worlds — with rocky cores like Earth but much smaller hydrogen-helium envelopes than Neptune — are much more common in other planetary systems. Jupiter’s migratory journey would have cleared any young super-earths from the inner solar system. The rocky worlds we see today began forming afterwards, and were thus much smaller than expected.

The simple division of our solar system into rocky and gassy worlds is the result of a complex planetary dance that in many ways defies the odds, and lies on the outskirts of what’s “normal” or, at least, average. But the galaxy is a very large place, with somewhere around 300 billion stars, and therefore, 300 billion chances at life, and of having rocky, Earth-like planets in their habitable zones. While there are likely many other planetary systems similar to ours, the vast majority will be devoid of anything like our home world. As we seek out new worlds with life — and potentially, new civilizations — on them, our best chance for an Earth-like planet might not be a planet like ours, but rather on a world that’s right out of Star Trek: the twin moons Remus and Romulus, orbiting a gas giant which in turn orbits its parent star.
We’ve now discovered thousands of stars with planets. Is ours really unique?
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Here's the little piece prompted by the picture:

The Fairy Lights

It nestled at the foot of a range of mountains. Man-made, the structure was still appreciated by the natural beings that had lived there long before it's first stone was placed. The woodland fairies loved the way it was lighted at night and watched from not far away. The humans that visited did so because they loved the splendor of the land, too. The forest fairies knew this and responded in kind. That single point of light, twinkling in a forest of blue spruce, warmed the trees even on the coldest winter night. As that light glowed so did their lives; still happy and free. And the humans watched from behind their own golden glow and wondered at the light among the night shrouded trees... somehow they felt it came from kindred spirits. And that, too, was the beauty of the land.
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Space | The first space walk

Via +Jenny Winder 

#space   #cccp  
 
Fifty years ago, cosmonaut Alexei Leonov became the first person to walk in space, climbing out of the Voskhod-2 spacecraft.
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Space | 25 years of Hubble

The best of the best of the best.

Via +SPACE.com 

#space   #hubble  
 
For the 25th anniversary of the Hubble Space Telescope in April 2015, 25 images were selected for a special gallery, one for each year of Hubble's lifespan.
For the 25th anniversary of the Hubble Space Telescope in April 2015, 25 images were selected for a special gallery, one for each year of Hubble's lifespan.
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Space | Comet 67P

The Sun creates 'hair' for the comet.

Via +European Space Agency, ESA 
#space   #comet  
 
Comet #67P with jets of material outflowing gloriously from the sunlit parts of both lobes - the latest #Rosetta Navcam #cometwatch image.

Details: http://blogs.esa.int/rosetta/2015/05/08/cometwatch-28-april/

Credit: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0
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Space | Mars

The red planet has a blue sunset and the blue planet has a red sunset. Weird universe.

From +Astronomy Picture of the Day (APoD)​ via +philippe roux

#space #earth #mars
 
Two Worlds, One Sun
Left Image Credit & Copyright: Damia Bouic; 
Right Image Credit: +NASA, +NASA Jet Propulsion Laboratory-Caltech, MSSS; Digital processing: Damia Bouic
http://apod.nasa.gov/apod/ap150512.html

How different does sunset appear from Mars than from Earth? For comparison, two images of our common star were taken at sunset, one from Earth and one from Mars. These images were scaled to have same angular width and featured here side-by-side. A quick inspection will reveal that the Sun appears slightly smaller from Mars than from Earth. This makes sense since Mars is 50% further from the Sun than Earth. More striking, perhaps, is that the Martian sunset is noticeably bluer near the Sun than the typically orange colors near the setting Sun from Earth. The reason for the blue hues from Mars is not fully understood, but thought to be related to forward scattering properties of Martian dust. The terrestrial sunset was taken in 2012 March from Marseille, France, while the Martian sunset was captured last month by NASA's robotic Curiosity rover from Gale crater on Mars.
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Space | Earth

From low earth orbit.

From +European Space Agency, ESA

#space #internationalspacestation
 
This abstract picture taken by ESA astronaut +Samantha Cristoforetti  from the International Space Station shows fishing boats illuminating the sea to attract fish into their nets. Clouds hanging over the area have blurred the lights; the black lines are areas without cloud cover.

http://www.esa.int/spaceinimages/Images/2015/05/Attracted_by_light

Credit: ESA/NASA
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Interesting! Would have been nice to have a scale bar in the pix, as we do for microscopic images. 
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Stories on google+ | +Brandon S. 

A shivery little start to a day in a dystopia where alarms go out for strange reasons, and responses to the alarms are ... extreme.

#storiesongoogleplus  
 
Welcome to a world where the most basic act can get you hunted.
Stretching the definition of "flash fiction" a tad, I present a three-part story. A story of a city where the worst crime you can commit, is the most natural thing in the world. It's called: ...
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Space | Europa

What causes these jumbled landscapes/icescapes? It could be impactors. It could be restless sub-surface lakes.

Whatever it is, Europa and Earth are the two locations in the solar system with significant quantities of water.

Via +Elizabeth Therese Niwel 

#space   #europa   #waterinspace  
 
Jupiter’s moon Europa is brimming with water. Although it is thought to be mostly made up of rocky material, the moon is wrapped in a thick layer of water – some frozen to form an icy crust, some potentially pooled in shallow underground lakes or layers of slush, and vast quantities more lurking even deeper still in the form of a giant subsurface ocean.   
This false-colour image from NASA’s Galileo spacecraft shows a disrupted part of Europa’s crust known as Conamara Chaos. The long criss-crossing grooves etched into the shattered chunks of ice are a perfect example of “chaos terrain” – a feature seen most prominently in our Solar System on Europa, Mars and Mercury.   
Although the exact ways chaos regions form are not completely understood, in the case of Europa scientists have a few ideas. One possibility is fast-moving impactors that smash through the moon’s brittle crust. As a liquid layer lies immediately beneath the crust, the shards are more mobile and can refreeze in different configurations, creating a fractured terrain with young scars carved into the icy plains.   
Many chaos regions have small impact craters clustered nearby. In the case of Conamara Chaos, for example, a large 26 km-diameter crater named Pwyll lies 1000 km to the south, and a handful of smaller, 500 m-diameter craters are scattered throughout the region, likely formed by lumps of ice thrown up by the impact that created Pwyll.   
Another suggestion is that Europa harbours an intricate system of shallow subsurface lakes. Instead of an object slamming into the Jovian moon, a lake system could influence and stress the crust from below to cause the thin ice sheets to fracture and collapse.   
This patch of Europa’s crust takes on an iridescent appearance in this false-colour image, which strongly enhances subtle colour differences present in the scene. Areas of blue and white stand out distinctly from areas of rusty orange and bronze. This colouration is thought to be caused by material from Pwyll: when the crater formed it threw up a blanket of fine ice particles that settled over parts of Conamara Chaos, colouring parts of the landscape in dark blue (coarser particles of ice), light blue (smaller particles) and white (very fine particles). The bronze patches are regions of ice that have been stained by minerals from beneath the disrupted crust.   
Although astronomers have studied Europa intensively, the only way to confirm the structure and composition of the moon is to probe its shell and interior with a space probe. ESA’s JUpiter ICy moons Explorer (Juice) mission aims to do just that when it arrives in the Jovian system in 2030. Alongside detailed studies of Jupiter itself, Juice will explore and characterise three of the gas giant’s potentially habitable icy moons: Ganymede, Europa and Callisto. The mission is in development, on track for launch in 2022.   
North is to the top of the picture and the Sun illuminates the surface from the right side of the frame. The image is centred at 9ºN / 274ºW, and covers an area of some 70 km by 30 km. The image combines data taken by Galileo’s Solid State Imaging system during three orbits through the Jovian system in 1996 and 1997.
Jupiter’s moon Europa is brimming with water. Although it is thought to be mostly made up of rocky material, the moon is wrapped in a thick layer of water – some frozen to form an icy crust, some potentially pooled in shallow underground lakes or layers of slush, and vast quantities more …
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+Jyoti Q Dahiya - that is so very kind of you, to say so. I appreciate enormously, and I'm not used to get such kind compliment.    :)
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Space | Earth and Moon

That's how dim the moon really is. Dark, dusky, beautifully black.

Via +SPACE.com 

#space   #moon   #earth   #internationalspacestation  
 
Astronauts adore looking at the Earth. It's something they've talked about in interviews, in books and sometimes, even in song. In recent years, space fans have been lucky enough to have astronauts sharing their amazing views of our planet on Twitter.
Astronauts adore looking at the Earth. It's something they've talked about in interviews, in books and sometimes, even in song. In recent years, space fans have been lucky enough to have astronauts sharing their amazing views of our planet on Twitter.
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Space | Beware the cave

Heh, couldn't resist the pun! But caves are where places like the Moon or Mars would hide their water from the near-vacuum of their 'atmospheres'.

Via +European Space Agency, ESA 
#space   #mars  
 
Ever wonder if there are underground caverns on Mars? Caves: the hidden side of planets.

http://blogs.esa.int/caves/2015/05/06/caves-the-hidden-side-of-planets/

#caves #blog +CAVES ESA 
Tweet There are thousands of kilometers of unexplored caves on Earth. But speleologists are wondering if planets such as Mars could have cave systems as well. And our imagination runs… How big could they be? How long are they? In science fiction novels and movies extraterrestrial caves are huge galleries even spaceships can fly through. They often host monstrous creatures, as shown in films such as Star Wars, Dune or more recently Prometeus. The ...
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Science fiction fan, voracious reader, loves puns, cartoons and pretty photos, and anything sciencey.
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Made it easier for people worldwide to take their spare tyre out of the boot; was the first person to realise software could be sold with advertising (was in print with this before hotmail was launched). Neither my spouse nor my kid hates me yet.
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