The Cosmic Web:
Observations and simulations of the intergalactic medium reveal the largest structures in the universe
by Robert Simcoe

There is no such thing as empty space. The idea of absolute emptiness realizes its closest approximation in the barren expanses between the stars and the galaxies, but even the most remote corners of the universe are suffused with very low density gas—which becomes increasingly rarefied as one ventures farther away from the places where galaxies consort.
Consider this fact: In the air we breathe, each cubic centimeter contains roughly 5 X 1019 atoms. In contrast, the intergalactic medium has a density of only 10–6 particles per cubic centimeter—each atom inhabits a private box a meter on each side.
This would seem to suggest that there is not much matter in the intergalactic medium. But, given the enormous volume between the galaxies, it quickly adds up: The combined atomic mass of intergalactic gas exceeds the combined atomic mass of all the stars and galaxies in the universe—possibly by as much as 50 percent! There is indeed something in empty space.
As cosmologists construct new narratives of the universe’s evolution from its beginning—the Big Bang—to the present day, it is becoming clear that we must understand the physics of intergalactic matter if we are to write the history of how the galaxies, stars and planets formed. In the past decade, rapid advances in both the design of telescopes and computing power have allowed us to study the remote corners of intergalactic space in unprecedented detail. These new results deepen our understanding of how the grandest structures in the universe formed and evolved…
(read more: American Scientist)
Images courtesy of Renyue Cen, Princeton University

The Cosmic Web:

Observations and simulations of the intergalactic medium reveal the largest structures in the universe

by Robert Simcoe

There is no such thing as empty space. The idea of absolute emptiness realizes its closest approximation in the barren expanses between the stars and the galaxies, but even the most remote corners of the universe are suffused with very low density gas—which becomes increasingly rarefied as one ventures farther away from the places where galaxies consort.

Consider this fact: In the air we breathe, each cubic centimeter contains roughly 5 X 1019 atoms. In contrast, the intergalactic medium has a density of only 10–6 particles per cubic centimeter—each atom inhabits a private box a meter on each side.

This would seem to suggest that there is not much matter in the intergalactic medium. But, given the enormous volume between the galaxies, it quickly adds up: The combined atomic mass of intergalactic gas exceeds the combined atomic mass of all the stars and galaxies in the universe—possibly by as much as 50 percent! There is indeed something in empty space.

As cosmologists construct new narratives of the universe’s evolution from its beginning—the Big Bang—to the present day, it is becoming clear that we must understand the physics of intergalactic matter if we are to write the history of how the galaxies, stars and planets formed. In the past decade, rapid advances in both the design of telescopes and computing power have allowed us to study the remote corners of intergalactic space in unprecedented detail. These new results deepen our understanding of how the grandest structures in the universe formed and evolved…

(read more: American Scientist)

Images courtesy of Renyue Cen, Princeton University

A giant, 100-foot-diameter (30 meters) telescope has been green-lighted for construction on the island of Hawaii.

When it begins operations, TMT will enable astronomers to explore objects inside the solar system, stars throughout the Milky Way and neighboring galaxies, and forming galaxies at the farthest edge of the observable universe…

Cassiopeia A - A Star Explodes and Turns Inside Out
A new X-ray study of the remains of an exploded star indicates that the supernova that disrupted the massive star may have turned it inside out in the process. Using very long observations of Cassiopeia A (or Cas A), a team of scientists has mapped the distribution of elements in the supernova remnant in unprecedented detail. This information shows where the different layers of the pre-supernova star are located three hundred years after the explosion, and provides insight into the nature of the supernova…
(read more: Chandra X-Ray Observatory)
image: Illustration: NASA/CXC/M.Weiss; X-ray: NASA/CXC/GSFC/U.Hwang & J.Laming

Cassiopeia A - A Star Explodes and Turns Inside Out

A new X-ray study of the remains of an exploded star indicates that the supernova that disrupted the massive star may have turned it inside out in the process. Using very long observations of Cassiopeia A (or Cas A), a team of scientists has mapped the distribution of elements in the supernova remnant in unprecedented detail. This information shows where the different layers of the pre-supernova star are located three hundred years after the explosion, and provides insight into the nature of the supernova…

(read more: Chandra X-Ray Observatory)

image: Illustration: NASA/CXC/M.Weiss; X-ray: NASA/CXC/GSFC/U.Hwang & J.Laming

Planetary Nebulas - Fast Winds From Dying Stars
This panel of composite images shows part of the unfolding drama of the last stages of the evolution of sun-like stars.
Dynamic elongated clouds envelop bubbles of multimillion degree gas produced by high-velocity winds from dying stars. In these images, Chandra’s X-ray data are shown in blue, while green and red are optical and infrared data from Hubble.
Planetary nebulas - so called because some of them resemble a planet when viewed through a small telescope - are produced in the late stages of a sun-like star’s life. After several billion years of stable existence (the sun is 4.5 billion years old and will not enter this phase for about 5 billion more years) a normal star will expand enormously to become a bloated red giant. Over a period of a few hundred thousand years, much of the star’s mass is expelled at a relatively slow speed of about 50,000 miles per hour…
(read more: Chandra X-Ray Observatory)

Planetary Nebulas - Fast Winds From Dying Stars

This panel of composite images shows part of the unfolding drama of the last stages of the evolution of sun-like stars.

Dynamic elongated clouds envelop bubbles of multimillion degree gas produced by high-velocity winds from dying stars. In these images, Chandra’s X-ray data are shown in blue, while green and red are optical and infrared data from Hubble.

Planetary nebulas - so called because some of them resemble a planet when viewed through a small telescope - are produced in the late stages of a sun-like star’s life. After several billion years of stable existence (the sun is 4.5 billion years old and will not enter this phase for about 5 billion more years) a normal star will expand enormously to become a bloated red giant. Over a period of a few hundred thousand years, much of the star’s mass is expelled at a relatively slow speed of about 50,000 miles per hour…

(read more: Chandra X-Ray Observatory)

A Watery, Extraterrestrial Ocean Is Submerged Beneath Enceladus’s Blankets of Ice
by Allison Eck
Move over, Mars. In the search for extraterrestrial life, moons are now in the limelight.
Enceladus, one of the Ringed Planet’s icy and austere orbiters has been on astronomers’ shortlist of potential hosts of alien life, especially since they discovered geysers of ice crystals shooting out of its south pole in 2005. They hypothesized that a deep ocean the size of Lake Superior sits underneath its highly tectonic and veiny surface, potentially feeding those gushers.
Normally, liquid water couldn’t exist that far out in the solar system, but the gravitational pull of Enceladus’s neighbor, Dione, bends the icy moon’s outer layer, creating heat through friction. NASA’s Cassini spacecraft has repeatedly flown by the surface of Enceladus to better understand the temperature dynamics that create these explosive geysers…
(read more: Nova Next - PBS)

A Watery, Extraterrestrial Ocean Is Submerged Beneath Enceladus’s Blankets of Ice

by Allison Eck

Move over, Mars. In the search for extraterrestrial life, moons are now in the limelight.

Enceladus, one of the Ringed Planet’s icy and austere orbiters has been on astronomers’ shortlist of potential hosts of alien life, especially since they discovered geysers of ice crystals shooting out of its south pole in 2005. They hypothesized that a deep ocean the size of Lake Superior sits underneath its highly tectonic and veiny surface, potentially feeding those gushers.

Normally, liquid water couldn’t exist that far out in the solar system, but the gravitational pull of Enceladus’s neighbor, Dione, bends the icy moon’s outer layer, creating heat through friction. NASA’s Cassini spacecraft has repeatedly flown by the surface of Enceladus to better understand the temperature dynamics that create these explosive geysers…

(read more: Nova Next - PBS)

Stalking the Shadow Universe
by Dennis Overbye
For centuries people have found meaning — or thought they did — in what they could see in the sky, the shapes of the constellations echoing old myths, the sudden feathery intrusion of comets, the regular dances of the planets, the chains of galaxies, spanning unfathomable distances of time and space.
Since the 1980s, however, astronomers have been forced to confront the possibility that most of the universe is invisible, and that all the glittering chains of galaxies are no more substantial, no more reliable guides to physical reality, than greasepaint on the face of a clown.
The brute mathematical truth is that atoms, the stuff of stars, you and me, make up only 5 percent of the universe by weight. A quarter of it is made of mysterious particles known as dark matter, and the remaining 70 percent a mysterious form of energy called dark energy. Physicists theorize that dark matter could be exotic particles left over from the Big Bang. They don’t know what it is, but they can deduce that dark matter is there by its gravitational effect on the things they can see. If Newton’s laws of gravity held over cosmic distances, huge amounts of more matter than we can see were needed to provide the gravitational glue to keep clusters of galaxies from flying apart, and to keep the stars swirling around in galaxies at high speed…
(read more: NY Times)

Stalking the Shadow Universe

by Dennis Overbye

For centuries people have found meaning — or thought they did — in what they could see in the sky, the shapes of the constellations echoing old myths, the sudden feathery intrusion of comets, the regular dances of the planets, the chains of galaxies, spanning unfathomable distances of time and space.

Since the 1980s, however, astronomers have been forced to confront the possibility that most of the universe is invisible, and that all the glittering chains of galaxies are no more substantial, no more reliable guides to physical reality, than greasepaint on the face of a clown.

The brute mathematical truth is that atoms, the stuff of stars, you and me, make up only 5 percent of the universe by weight. A quarter of it is made of mysterious particles known as dark matter, and the remaining 70 percent a mysterious form of energy called dark energy. Physicists theorize that dark matter could be exotic particles left over from the Big Bang. They don’t know what it is, but they can deduce that dark matter is there by its gravitational effect on the things they can see. If Newton’s laws of gravity held over cosmic distances, huge amounts of more matter than we can see were needed to provide the gravitational glue to keep clusters of galaxies from flying apart, and to keep the stars swirling around in galaxies at high speed…

(read more: NY Times)

NGC 2467 is a star-forming region with a visual appearance often likened to a skull or a mandrill. Located in the southern constellation of Puppis, it contains the open clusters Haffner 18 (centre) and Haffner 19 (middle right: located inside the smaller pink “eye”), as well as vast areas of ionised gas. The bright star at the centre of the largest pink region is HD 64315, a massive young star that is helping to shape the whole nebular region’s structure.
 Photograph: European Southern Observatory
(via: Wikipedia)

NGC 2467 is a star-forming region with a visual appearance often likened to a skull or a mandrill. Located in the southern constellation of Puppis, it contains the open clusters Haffner 18 (centre) and Haffner 19 (middle right: located inside the smaller pink “eye”), as well as vast areas of ionised gas. The bright star at the centre of the largest pink region is HD 64315, a massive young star that is helping to shape the whole nebular region’s structure.

Photograph: European Southern Observatory

(via: Wikipedia)

Artist’s Concept: A close-up of Super Nova 2006gy  This artist’s illustration shows what the brightest supernova ever recorded, known as SN 2006gy, may have looked like. The fireworks-like material (white) shows the explosive death of an extremely massive star. Before it exploded, the star expelled the lobes of cool gas (red). As the material from the explosion crashes into the lobes, it heats the gas in a shock front (green, blue and yellow) and pushes it backward.Illustration: NASA/CXC/M.Weiss (via: Chandra X-Ray Observatory)

Artist’s Concept: A close-up of Super Nova 2006gy

This artist’s illustration shows what the brightest supernova ever recorded, known as SN 2006gy, may have looked like. The fireworks-like material (white) shows the explosive death of an extremely massive star. Before it exploded, the star expelled the lobes of cool gas (red). As the material from the explosion crashes into the lobes, it heats the gas in a shock front (green, blue and yellow) and pushes it backward.

Illustration: NASA/CXC/M.Weiss

(via: Chandra X-Ray Observatory)

Comet Pan-STARRS Makes Stunning ‘Galactic Flyby’
by Megan Gannon, SPACE.com News Editor
A NASA probe recently spotted the dazzling Pan-STARRS comet as it hurtled through space against the backdrop of a distant galaxy.

Pan-STARRS is a fresh visitor from the outer solar system that lit up night skies last spring as it made one of its first approaches toward the sun. Officially christened comet C/2012 K1, it was discovered a few years ago by the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS, in Hawaii.

NASA released a stunning new series of images of Comet Pan-STARRS captured by the NEOWISE mission on May 20, 2014, when Pan-STARRS was 143 million miles (230 million kilometers) away from Earth…
(read more: Discovery News)

Comet Pan-STARRS Makes Stunning ‘Galactic Flyby’

by Megan Gannon, SPACE.com News Editor

A NASA probe recently spotted the dazzling Pan-STARRS comet as it hurtled through space against the backdrop of a distant galaxy.

Pan-STARRS is a fresh visitor from the outer solar system that lit up night skies last spring as it made one of its first approaches toward the sun. Officially christened comet C/2012 K1, it was discovered a few years ago by the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS, in Hawaii.

NASA released a stunning new series of images of Comet Pan-STARRS captured by the NEOWISE mission on May 20, 2014, when Pan-STARRS was 143 million miles (230 million kilometers) away from Earth…

(read more: Discovery News)

A Look at Today’s Sun (July 10, 2014) 
This is a composite image and is one of my favorite views of our Sun!  This image combines three images with different, but very similar, temperatures. The colors are assigned differently than in the single images. Here AIA 211 is red, AIA 193 is green, and AIA 171 is blue. Each highlights a different part of the corona. 211 highlights the active region of the outer atmosphere of the Sun - the corona. Active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas - called coronal holes - are places where very little radiation is emitted, yet are the main source of solar wind particles. The temperatures are about 3.6 million F…
(read more: NASA - Solar Dynamics Observatory)

A Look at Today’s Sun (July 10, 2014)

This is a composite image and is one of my favorite views of our Sun!

This image combines three images with different, but very similar, temperatures. The colors are assigned differently than in the single images. Here AIA 211 is red, AIA 193 is green, and AIA 171 is blue. Each highlights a different part of the corona.

211 highlights the active region of the outer atmosphere of the Sun - the corona. Active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas - called coronal holes - are places where very little radiation is emitted, yet are the main source of solar wind particles. The temperatures are about 3.6 million F…

(read more: NASA - Solar Dynamics Observatory)

We talk to the man who explained how the big bang banged.

In March, Guth sat in the auditorium of the Harvard-Smithsonian Center for Astrophysics, a storied center of astronomy on the other side of Cambridge, Massachusetts, from MIT.

He waited in the audience, along with Stanford’s Andrei Linde, 66, another inflation theorist, to hear from the BICEP2 astrophysics team that had spent three years looking with an unblinking telescope at one small patch of sky above the frozen waste of Antarctica.

They had looked inside that patch at the most distant thing observable in the cosmos, the so-called cosmic microwave background, or CMB. The CMB emanates from every corner of the sky—leftover heat from the first 380,000 years of the universe’s history after the big bang…