Cassini Spacecraft Reveals 101 Geysers 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.

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.

The fact that Enceladus’ sea is salty, laced with organic compounds, spouting into space, and maybe even rising up to the surface has raised this particular Saturnian moon as a major target for future exploration.


Cross-section of Ice Shell (Artist rendering)

Credit: NASA JPL

(Source: jpl.nasa.gov)

The Colorful Demise of a Sun-like Star


This Hubble Space Telescope image shows planetary nebula NGC 2440 with a star very similar to our Sun reaching the end of its life. The star is casting off its outer layers of gas, which formed a cocoon around the star’s remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the center. The white dwarf is one of the hottest known, with a surface temperature of nearly 400,000 degrees Fahrenheit (200,000 degrees Celsius).

The nebula’s chaotic structure suggests that the star shed its mass episodically. During each outburst, the star expelled material in a different direction. This can be seen in the two bow tie-shaped lobes. Our Sun will eventually burn out and shroud itself with stellar debris as well, but luckily not for another 5 billion years.

(Credit: NASA, ESA, and K. Noll (STScI)

(Source: hubblesite.org)

spaceplasma:

Animations of Saturn’s aurorae

Earth isn’t the only planet in the solar system with spectacular light shows. Both Jupiter and Saturn have magnetic fields much stronger than Earth’s. Auroras also have been observed on the surfaces of Venus, Mars and even on moons (e.g. Io, Europa, and Ganymede). The auroras on Saturn are created when solar wind particles are channeled into the planet’s magnetic field toward its poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. Aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet’s magnetosphere.  The main source is the small moon Enceladus, which ejects water vapor from the geysers on its south pole, a portion of which is ionized. The interaction between Saturn’s magnetosphere and the solar wind generates bright oval aurorae around the planet’s poles observed in visible, infrared and ultraviolet light. The aurorae of Saturn are highly variable. Their location and brightness strongly depends on the Solar wind pressure: the aurorae become brighter and move closer to the poles when the Solar wind pressure increases.

Credit: ESA/Hubble (M. Kornmesser & L. Calçada)

8,000 light-years from Earth lies the incredible NGC 3292 star cluster in the constellation of Carina. Most of the stars seen here are very young, and the cluster itself is less than 10 million years old. Comparatively, our Sun is 4.6 billion years old and is only halfway through its lifecycle.

NGC 3292 is an “open cluster”, formed from a giant cloud of molecular gas. The stars are held together by their mutual gravitational attraction. But these forces are not enough to hold a cluster together against close encounters with other clusters and clouds of gas as the cluster’s own gas and dust dissipates. So, open clusters will only last a few hundred million years, unlike larger globular clusters, which can survive for billions of years, and hold on to far more stars.

(
Image credit: La Silla Observatory in Chile, ESO/G. Beccari)

(Source: eso.org)

Chandra X-ray Observatory Celebrates 15th Anniversary

To celebrate, the Chandra team released four newly processed images of supernova remnants.

TYCHO
More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of the exploded star produced a shock wave moving outward into the surrounding interstellar gas, and another, reverse shock wave moving back into the expanding stellar debris. This Chandra image of Tycho reveals the dynamics of the explosion in exquisite detail. The outer shock has produced a rapidly moving shell of extremely high-energy electrons (blue), and the reverse shock has heated the expanding debris to millions of degrees (red and green). There is evidence from the Chandra data that these shock waves may be responsible for some of the cosmic rays - ultra-energetic particles - that pervade the Galaxy and constantly bombard the Earth.

THE CRAB NEBULA
In 1054 AD, Chinese astronomers and others around the world noticed a new bright object in the sky. This “new star” was, in fact, the supernova explosion that created what is now called the Crab Nebula. At the center of the Crab Nebula is an extremely dense, rapidly rotating neutron star left behind by the explosion. The neutron star, also known as a pulsar, is spewing out a blizzard of high-energy particles, producing the expanding X-ray nebula seen by Chandra. In this new image, lower-energy X-rays from Chandra are red, medium energy X-rays are green, and the highest-energy X-rays are blue.

3C58
3C58 is the remnant of a supernova observed in the year 1181 AD by Chinese and Japanese astronomers. This new Chandra image shows the center of 3C58, which contains a rapidly spinning neutron star surrounded by a thick ring, or torus, of X-ray emission. The pulsar also has produced jets of X-rays blasting away from it to both the left and right, and extending trillions of miles. These jets are responsible for creating the elaborate web of loops and swirls revealed in the X-ray data. These features, similar to those found in the Crab, are evidence that 3C58 and others like it are capable of generating both swarms of high-energy particles and powerful magnetic fields. In this image, low, medium, and high-energy X-rays detected by Chandra are red, green, and blue respectively.

G292.0+1.8:
At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. These oxygen-rich supernovas are of great interest to astronomers because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people. The X-ray image from Chandra shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen (yellow and orange), other elements such as magnesium (green) and silicon and sulfur (blue) that were forged in the star before it exploded.

Credit: 
http://chandra.harvard.edu

The famous theoretical physicist John Archibald Wheeler coined the term “It from Bit”. He says that ”It” — every particle, every field of force, even the space-time continuum itself — derives its function, its meaning, its very existence entirely — even if in some contexts indirectly — from the apparatus-elicited answers to yes-or-no questions, binary choices, “bits.” This concept symbolizes the idea that every item of the physical world has at bottom — a very deep bottom, in most instances — an immaterial source and explanation; that which we call reality arises in the last analysis from the posing of yes-or-no questions and the registering of equipment-evoked responses; in short, that all things physical are information-theoretic in origin and that this is a participatory universe.

Wheeler speculated that we are part of a universe that is a work in progress; we are tiny patches of the universe looking at itself — and building itself. It’s not only the future that is still undetermined but the past as well. And by peering back into time, even all the way back to the Big Bang, our present observations select one out of many possible quantum histories for the universe.

At every moment, in Wheeler’s view, the entire universe is filled with events, where the possible outcomes of countless interactions become real, where the infinite variety inherent in quantum mechanics manifests as a physical cosmos. And we see only a tiny portion of that cosmos. Wheeler suspected that most of the universe consists of huge clouds of uncertainty that have not yet interacted either with a conscious observer or even with some lump of inanimate matter. He sees the universe as a vast arena containing realms where the past is not yet fixed.

from Does the Universe Exist if We’re Not Looking?


Also check out fromquarkstoquasars article: John Wheeler’s Participatory Universe

pennyfornasa:

"A scientific colleague tells me about a recent trip to the New Guinea highlands where she visited a stone age culture hardly contacted by Western civilization. They were ignorant of wristwatches, soft drinks, and frozen food. But they knew about Apollo 11. They knew that humans had walked on the moon. They knew the names of Armstrong and Aldrin and Collins. They wanted to know who was visiting the moon these days." - Carl Sagan

After traveling four days and more than 238,900 miles, the Lunar Module Eagle began its descent to the surface of the Moon. Very early on, however, it became clear to Aldrin and Armstrong that their telemetry was incorrect as they recognized lunar landmarks were being passed too early. At approximately 6,000 miles above the surface, numerous guidance computer program alarms distracted the crew as they communicated with flight controllers. Mission Control engineers soon reassured the Eagle to continue with the descent as it was determined that their system was being overloaded with extra tasks not necessary to land on the Moon. After looking out of the window a few moments later, Armstrong was forced to take semi-manual control as he noticed that the navigational systems were guiding them towards an area comprised of boulders and an uneven landing surface. This manual override would require Aldrin to call out velocity and altitude data before landing fuel ran out. After a somewhat frantic period, the Lunar Module safely landed on the moon on July 20th, 1969 — with about 25 seconds of fuel remaining.

As an estimated 600 million people watched, Neil Armstrong became the first ambassador of the planet Earth to walk on another world. For over 2.5 hours, he and Buzz Aldrin captured the imagination of our species as they performed various scientific and geological experiments. Along with planting an American flag, a commemorative plaque marking this monumental human achievement was mounted to the Apollo 11 Lunar Module — and remains as a relic of humanity’s first journey on the Moon.

“We came in peace for all mankind. That statement really to me was a very symbolic one — not just of our mission, but of the entire Apollo effort.” - Buzz Aldrin, Apollo 11 Lunar Module Pilot

Apollo 11 was arguably our most exciting adventure, and over the span of three years, NASA sent a total of 12 astronauts to explore the Moon. However, not since 1972 have human beings been beyond low-Earth orbit. Please watch our video, The Spirit of Apollo, and consider what raising the NASA budget will once again do for our society.

https://www.youtube.com/watch?v=_G6jhUznonU

Galactic Center of Our Milky Way

The Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory — collaborated to produce an unprecedented image of the central region of our Milky Way galaxy.

Observations using infrared light and X-ray light see through the obscuring dust and reveal the intense activity near the galactic core. The center of the galaxy is located within the bright white region in the upper portion of the image. The entire image covers about one-half a degree, about the same angular width as the full moon.

Each telescope’s contribution is presented in a different color:

  • Yellow represents the near-infrared observations of Hubble. They outline the energetic regions where stars are being born as well as reveal hundreds of thousands of stars.
  • Red represents the infrared observations of Spitzer. The radiation and winds from stars create glowing dust clouds that exhibit complex structures from compact, spherical globules to long, stringy filaments.
  • Blue and violet represents the X-ray observations of Chandra. X-rays are emitted by gas heated to millions of degrees by stellar explosions and by outflows from the supermassive black hole in the galaxy’s center. The bright blue blob toward the bottom of the full field image is emission from a double star system containing either a neutron star or a black hole.

(Source: chandra.harvard.edu)

Massive Meteorite Discovered on Mars

NASA’s Mars rover Curiosity has discovered its first meteorite on the Red Planet. Named “Lebanon”, it is 7 nearly feet wide and made of iron. The picture on top was made by combining high-resolution circular images (outlined in white) acquired with the Remote Micro-Imager (RMI) of Curiosity’s ChemCam instrument with color and context from the rover’s Mastcam.

The second image shows three meteorites on the Martian surface from a distance, including Lebanon.

Iron meteorites are not rare among meteorites found on Earth, but they are less common than stony meteorites. On Mars, iron meteorites dominate the small number of meteorites that have been found. Part of the explanation could come from the resistance of iron meteorites to erosion processes on Mars. 


(Credit: NASA/JPL Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS/MSSS)

(Source: mars.jpl.nasa.gov)

"For as long as there been humans we have searched for our place in the cosmos. Where are we? Who are we? We find that we live on an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. This perspective is a courageous continuation of our penchant for constructing and testing mental models of the skies; the Sun as a red-hot stone, the stars as a celestial flame, the Galaxy as the backbone of night." – CARL SAGAN 

(Photography credit: Michael Goh)

I shared the Cat’s Paw Nebula (NGC 6334) several months ago but wanted to share this incredible infrared version taken by the VISTA telescope.

Cat’s Paw is a vast region of star formation about 5500 light-years from Earth in the constellation of Scorpius. The whole gas cloud is about 50 light-years across. It is one of the most active nurseries of young massive stars in our galaxy, some nearly ten times the mass of our Sun and most born in the last few million years.

 (Credit: ESO Astronomy/J. Emerson/VISTA Acknowledgment: Cambridge Astronomical Survey Unit)

Nebula NGC 6888 is the result of fierce winds of subatomic particles blown off by the star WR 136, a massive blue monster a quarter million times more luminous than our Sun. The nebula is the result of a previously ejected wind of material being slammed by faster matter ejected more recently.

In a few million years WR 136 will explode, sending out 
much faster material which will sweep outward and destroy the nebula as we see it now.

(Image credit: Mark Hanson; Description credit: Phil Plait)