All things Are Fire
COSMOLOGY FILE

"All things are composed of fire and are again resolved into fire. " The Greek phiosopher, Father of Dialectics and Pantheism, Heraclitus, said that and now NASA has proved it...... Astronomers say Draco's glow is the beginning of time Cosmologists estimate that the Big Bang was 13.7 billion years ago. Some 200 million years passed after this act of creation before the first stars began to form from cosmic particles and dust. Scientists believe these stars were likely to have been more than 100 times more massive than the Sun, and would have been hot, bright and relatively short-lived, each surviving a few million years compared to the billions of years of conventional stars.

Top image from NASA's Spitzer Space Telescope of stars and galaxies in constellation Draco. Bottom image shows glow attributed to first stars in the universe after radiation from other stars and galaxies is removed. (Courtesy: NASA/JPL-Caltech/A. Kashlinsky/GSFC)

And once again the famed mythological monster the; Dragon (Draco) has touched our conciousness....

While more mysteries become revealed as Heraclitus predicted: "The things that exist are brought into harmony by the clash of opposing currents. All things come into being by the conflict of opposites"

Monster black hole lurking in our galaxy
02/11/2005 - 19:39:55

A super-massive object at the heart of the Milky Way is almost certainly a monster black hole, scientists said today.

New evidence appears to confirm that the black hole thought to lurk at the centre of our galaxy is real.

By observing radio emissions from the object, astronomers have also been able to measure it more accurately than ever before.

The results indicate that the “hole” is as wide as the Earth’s orbit round the Sun – considerably smaller than previous estimates suggested.

Yet it appears to contain a mass equivalent to four million Suns.

The findings seem to rule out an alternative theory that the object, known as Sagittarius A (Sgr A), is a cluster of super-dense dead stellar remnants known as neutron stars.

Matter at such a high density level would be very short-lived, collapsing further into a black hole in only around 100 years.

Astronomers believe all the evidence points towards Sgr A being a black hole - a region of space in which gravity is so strong that nothing can escape from it, not even light.

Scientists used 10 radio telescopes spread across the US and working as one gigantic antenna to capture the radio waves. The technique is known as Very Long Baseline Interferometry (VLBI).

Black holes emit radiation from matter swirling round the edge of the event horizon – the “point of no return” after which there is no escape from their gravity.

Writing in the journal Nature, the astronomers, led by Zhi-Qiang Shen, from Shanghai Astronomical Observatory in China, said the new radio image provided “strong evidence that Sgr A is a super-massive black hole”.

In an accompanying article, astronomer Christopher Reynolds, from the University of Maryland in College Park, USA, said scientists were now a step closer to the goal of actually taking a snapshot of a black hole.

The ultimate proof that black holes exist would be to obtain an image of the “shadow” produced by the event horizon, he said.

“The predicted diameter of the event horizon’s shadow for Sgr A is just 30 micro-arc seconds, or 120 millionth of a degree,” he said.

“This would be the apparent size of a tennis ball on the Moon when viewed from the Earth, and is about a factor of four smaller than the scales probed by the current VLBI experiments.”

Solved: the mysteries of the black hole

The concept of black holes, supermassive voids that suck in all matter and light, has caught the public imagination for decades. Now, for the first time, scientists are on the verge of looking into the heart of darkness.

By Steve Connor

Published: 03 November 2005

They are probably the strangest things in the known universe. Black holes are so massive and their gravitational pull is so strong that nothing can escape - not even light itself - which is strange indeed for something made of nothing.

A hole in space seems to make no sense at all, yet scientists are convinced that these prisons of light are for real, even though they have never really been seen and the only evidence for their existence is circumstantial.

But astronomers have now got close to staring a black hole in the face. With the help of an array of 10 radio telescopes in America, they have pictured the void at the centre of our own Milky Way galaxy 26 million light years away, where a supermassive black hole sits invisibly like the transparent eye of a hurricane.

This particular black hole is estimated to have a mass equivalent to four million Suns and yet the latest measurements, published in the journal Nature, suggest it occupies a volume with a radius less than the distance between the Earth and the Sun.

This is less than half the size previously estimated, indicating that astronomers are close to defining the crucial outer boundary of one of the most elusive phenomena in cosmology - one that has mystified scientists for decades. "We're getting tantalisingly close to being able to see an unmistakable signature that would provide the first concrete proof of a supermassive black hole at a galaxy's centre," said Zhi-Qiang Shen, of Shanghai Astronomical Observatory in China, one of the leaders of the study.

No light escapes from black holes, which is why they are so invisible. They can however be detected by the radiowaves emitted from their periphery as they gobble up any surrounding matter that falls within range.

The first sign of a black hole within our own galaxy came in February 1974, when two American astronomers, Bruce Balick and Robert Brown, detected a powerful source of radiowaves emanating from the constellation of Sagittarius. Balick and Brown calculated that, whatever the cause of the radiation, the source was coming from the dead centre of the galaxy. They suspected a black hole at the heart of the Milky Way and the race began for astronomers to capture the first image of this radio source, which they called Sagittarius A* (pronounced "A-star").

"Black holes are perhaps the most exotic objects to impinge on the cosmic consciousness," explains astronomer Christopher Reynolds of the University of Maryland, writing in Nature. "They are formed when matter such as that from a dying massive star collapses in calamitously under its own gravity, forming a region of space in which the gravitational field is so strong that it swallows all matter and radiation that come near it."

One way of looking at black holes is how they distort space and time. Imagine the space-time continuum as a rubber sheet. An object the size of the Sun would act like a heavy ball placed on a trampoline, causing a minor indentation. Heavier objects, such as cannonballs, would create further indentations in the space-time continuum but something as heavy and dense as a black hole would cause such a steep dent that it would be like a bottomless pit from which nothing could escape once it fell in.

>This view of black holes comes with the benefit of Einstein's theories of relativity. But the concept actually predated his pioneering work. In fact, black holes, like many cosmological phenomena, were predicted long before scientists began to construct the sort of instruments that could detect them.

Indeed, an English clergyman and scholar called John Michell predicted in 1784 that some stars might be so big, and hence so heavy or massive, that they would create a gravitational field strong enough to prevent light from escaping. If something was 500 times bigger than the Sun, the Rev Michell wrote, "all light emitted from such a body would be made to return towards it, by its own proper gravity".

Such predictions were based on what was known at the time from Isaac Newton's work on gravity. It was not until after Albert Einstein formulated his general theory of relativity that further work could be done on the theory of black holes - although no one actually called them by that name until 1967.

Using Einstein's theory, Karl Schwarzschild, a German physicist, discovered that relativity equations led to the predicted existence of an object so dense that other objects would fall into it and never come out again.

Schwarzschild talked about a "magic sphere" around such an object where gravity was so powerful that nothing within that sphere could escape. Furthermore, all matter within the sphere would be crushed to a point of infinite density occupying virtually no space. This point is known as the "singularity" and every black hole is believed to have a singularity at its centre.

J Robert Oppenheimer, the father of the American atom bomb, calculated that a black holes was the ultimate end-product of a star's lifecycle, the point when it collapsed in on itself and the resulting ultra-dense material gave rise to a singularity.

But the real turning point came in 1967, when the American astrophysicist, John Wheeler, actually coined the term "black hole" - and launched a wave of popular fascination with these gravity-defying voids.

In 1971, the first experimental evidence from space for the existence of black holes came with data captured by the American Uhuru satellite. Its instruments detected a source of X-rays coming from a star that appeared to be orbiting an invisible companion that was estimated to be five times the mass of the Sun.

This was the first of several contenders for the "smaller" kind of black hole caused by the collapse of a stellar objects. But in more recent years scientists have been chasing much, much bigger black holes.

These black holes are supermassive affairs, like the one at the centre of our own galaxy which is estimated to weigh in at about 4 million times the mass of the Sun.

But astronomers believe there are even bigger ones, 10 billion times the mass of the Sun, at the heart of every galaxy, said the cosmologist Marcus Chown, author of The Universe Next Door. "No one knows how they form. No one knows why they are at the centre of galaxies. It's even possible they were there first and seeded the formation of galaxies such as the Milky Way."

Such is the mystery surrounding black holes that a small minority of scientists still cannot quite bring themselves to believe in them. "The truth is we don't absolutely know for sure that black holes exist. No one has actually seen a black hole, " explained Mr Chown.

This is why the latest study is so important, because scientists are getting so tantalising close to taking that first image of a black hole in all its mysterious splendour. But what would "nothing" look like? How can we take an image of something that swallows up all matter and radiation?

Professor Reynolds said that we may not be able to see a black hole itself, but we should be able to see the boundary or "event horizon" beyond which all matter is swallowed up. "What is needed is a more discerning test than simply detecting something massive and compact; we need to find the event horizon, the defining property of a black hole," he said.

"As physical phenomena go, event horizons are tricky to observe... High-resolution imaging, however, does provide a compelling way to search for an event horizon. If a black hole is surrounded by an almost spherical distribution of radiation matter ... a sufficiently high-resolution image should reveal a shadow around it.

"This dark circle is caused by radiation from sources behind the black hole that are being swallowed by the event horizon. Surrounding this shadow would be a bright ring - the result of the strong deflection by the black hole's gravitational field of those light rays that do scrape past it."

Fred Lo, director of the US National Radio Astronomy Observatory, which runs the array of telescopes that collected the latest data, said that, with a slightly higher resolution, telescopes should soon be able to see this shadow of a black hole.

"The extremely strong gravitational pull of a black hole has several effects that would produce a distinctive 'shadow' that we think we could see if we can image details about half as small as those in our latest images," Dr Lo said. "Seeing that shadow would be the final proof that a supermassive black hole is at the centre of our galaxy."

Mr Chown said that the best way to get the final elusive proof of the existence of supermassive black holes is to observe the one that is closest to us. "The proof will be to see a bright ring with a dark region inside it - presumably, the bright ring is matter super-heated as it falls into the black hole and the dark region is the black hole," Mr Chown said. "Fred Lo and his people have come the closest yet to getting that proof."

Black holes are so strange that they may defy the laws of physics as we know them, for instance by creating "wormholes" in space. When we are finally able to see black holes with our own eyes, we may have also found gateways to other universes.

Hubble Observations Add Two New Moons to Pluto

By Amir Alexander
November 3, 2005

As the New Horizons team prepares for the fast approaching January launch, they received startling news about the planet they are working so hard to reach. Images taken by the Hubble Space Telescope last May reveal that Pluto has not one moon, but three! These include Charon, the large moon discovered in 1978, and two previously unknown satellites, all orbiting within 60,000 kilometers (36,000 miles) of their home planet. As a result, when New Horizons visits the ninth planet in 2015 or thereabout, it will be able to study four separate objects, all in the immediate vicinity of Pluto itself.

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When New Horizons Principal Investigator Alan Stern of the Southwest Research Institute (SwRI), and Hal Weaver of the Johns Hopkins University Applied Physics Laboratory (APL), first proposed to use the Hubble Space Telescope to search for moons around Pluto, they were looking for something quite different. As co-leaders of a team of nine astronomers searching for Pluto companions, they thought they might find very distant moons orbiting Pluto, so faint that they have so far escaped detection. Other Kuiper belt objects (KBOs) are known to have such far-off moons.

Accordingly, they instructed Hubble to search the entire range of Pluto’s gravitational control, stretching out over 2 million kilometers from the planet. On May 15, 2005, and again on May 18, the space telescope pointed its mirror in the direction of Pluto, and took a series of pictures. The images show no trace of the distant satellites Stern and Weaver had expected. They do, however, show two bright spots orbiting very close to Pluto itself – almost certainly two small moons.

“Pluto always baffles us” mused Stern. “We never expected Pluto to be a quadruple.”

Click to enlarge >

A View from Pluto's Moon
An artist's conception of the view from one of Pluto's new moons showing Pluto, Charon, and the other small moon. Credit: NASA, ESA, G. Bacon

The first to notice the two bright points in the Hubble images was Max Mutchler of the Space Telescope Science Institute, who inspected the images on June 15, at Weaver’s request. After informing Weaver of the possible discovery, both had to put any plans for further confirmation aside: for the next several months both researchers focused on the Hubble observations of comet Tempel 1, which was struck by an impactor from the spacecraft Deep Impact.

In the meantime, at SwRI, Stern suggested to postdoctoral researcher Andrew Steffl that he too take a look at the images and see what he could find. Although this was done in coordination with Weaver, Weaver did not inform Stern and Steffl of Mutchler’s suspicions so as not to bias their observations. By mid August Steffl too had found two apparent satellites of Pluto. By the end of the month it was clear that he had found the same objects as Mutchler, in the very same images.

To confirm the discovery Stern and Weaver asked three of the largest ground-based telescopes to look for the moons. In September, The Keck and Gemini telescopes in Hawaii, and the European Southern Observatory’s Very Large Telescope (VLT) in Chile all set their sights on Pluto. None, however, succeeded in imaging the elusive satellites, most likely because Pluto was already low in the sky at twilight and barely visible. In February, when Pluto is farther away from the glare of the Sun, a new series of observations is planned with Hubble.

Even without the confirming observations, Stern, Weaver, and their colleagues have very good reasons to believe the moons they have found are the “real thing.” First there is the fact that the objects move through the sky with Pluto. Other KBO’s, and background stars, which follow a different path through the skies, appear in the images as blurry streaks, while the suspected moons remain in focus.

Then there are the results of preliminary calculations of the two satellites’ orbits. These appear to be nearly circular, and on the same orbital plane as Pluto’s large moon Charon. Stern, furthermore, suggests that the moons appear to be in resonance with Charon, meaning that the ratio of the moons’ orbital periods and that of Charon is a simple integer ration such as 2:1 or 3:2. The chances that such apparent orbits are artifacts of the random movement of background objects is miniscule. However, these would be precisely the orbits that one would expect of moons formed by the same impact that created Charon.

Finally, and perhaps most convincingly – the two moons have been imaged before. Marc Buie of the Lowell Observatory and Eliot Young of SwRI found the moons in images of Pluto taken by Hubble in 2002.

Click to enlarge >

Pluto's Quadruple System
These images taken by the Hubble Space Telescope's Advanced Camera for Surveys (ACS) on May 15 and 18, 2005, show that Pluto has two small moons in addition to its large moon Charon. Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the Hubble Space Telescope Pluto Companion Search Team

The two moons, provisionally known as S/2005 P 1 and S/2005 P 2, are tiny compared to their two companions. Whereas Pluto is 2400 kilometers (1400 miles) in diameter, and Charon is half of that, the diameter of S/2005 P 1 – the larger of the two moons – is anywhere between 50 and 160 kilometers (30 and 100 miles). Since size estimates depend on the object’s brightness, the exact diameter of the moon depends on its reflectivity (or albedo), which right now can only be guessed at. The smaller moon, S/2005 P 2, is likely 10% - 15% smaller than its sibling.

Pluto’s newfound companions could provide scientists with new insights on the Kuiper belt and the Pluto system. If the findings prove correct, said Weaver, Pluto “will become the first body in the Kuiper belt known to have more than one satellite.” This suggests that among the estimated 40,000 Kuiper belt objects that have moons, many may have more than one. Furthermore, the size and orbits of moons are a crucial resource for learning about their host planets. The two new satellites will soon enable scientists to calculate better estimates of the mass and density of Pluto and Charon. Down the road, when more is known about S/2005 P 1 and S/2005 P 2, they could help us understand the origins and history of the Pluto system as well.

Apart from their importance to our understanding of the Kuiper belt, and their influence on plans for New Horizons, the discovery of two new moons orbiting close to one of the traditional nine planets is a remarkable discovery in itself. Stern put it most aptly: “It blew our socks off,” he said.

Solved: the mysteries of the black hole

The concept of black holes, supermassive voids that suck in all matter and light, has caught the public imagination for decades. Now, for the first time, scientists are on the verge of looking into the heart of darkness.

By Steve Connor

Published: 03 November 2005

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