Venus

Earth's evil twin has been in the news recently after an amateur astronomer noticed a bright spot in its atmosphere.While scientists have been scratching their heads over it, the main culprit is thought to be a huge volcanic eruption on the planet's surface.Somewhat on a tangent, Venus was where my favourite case of unlucky science ever occurred.Back in 1981, the Russians sent over Venera 14 to sample the planet's soil using a spring-loaded arm with a sensor on the end.Having made it to the surface, not the simplest feat, the probe unfurled the sensor and then happily relayed back the chemical composition of... a plastic lens cap that had fallen off the ship.

The Russians had gone 24 million miles to measure the chemistry of something that was made a couple of hundred miles away from mission control.Ouch!!Venus is, of course, Earth gone bad.How bad?

Here's a Weird Science Factoid Special to get your chops around:

The surface temperature of Venus is over 480 degrees C (900 degrees F).

The atmospheric pressure on the surface of Venus is that 90 times the pressure on Earth.If you were able to stand on the surface of Venus, it would feel like being one kilometre under the sea on Earth, a depth deep enough to sink a submarine.

The clouds of Venus are filled with sulfuric acid. You don't want to be around when it starts to rain.Venus rotates so slowly that it orbits the sun faster than it can make one whole rotation on its axis. In other words, Venus has a longer day (243 'Earth days') than year (224 days).

Venus and Mercury are the only two planets in the Solar System not to have a moon.It is believed that Venus used to have bodies of water similar to Earth, but dried up over a period of 300 million years when the sun began admitting more solar energy after the sun's infancy stage.

Venus has mountains that are higher than Earth. Maat Mons is more than five miles high.The planet rotates from East to West. The only other planet that does this is Uranus.Venus would have a cold climate if it weren't for the high concentration of carbon dioxide in its atmosphere (96 per cent).

After the Sun, the Moon and now the International Space Station, Venus is the brightest object in the night-sky from Earth.Venus' axis hardly has any tilt at all, unlike Mars and Earth. This means that, if it had a thin atmosphere, the planet would not have seasons.There are more volcanoes on Venus than on any other planet in the Solar System.Venus may now resemble what Earth will become in millions of years time, when the Sun expands and turns the heatup. Let's get out of here!

The Big Rip: New Theory Ends Universe by Shredding Everything

A rather harrowing new theory about the death of the universe paints a picture of "phantom energy" ripping apart galaxies, stars, planets and eventually every speck of matter in a fantastical end to time.

Scientifically it is just about the most repulsive notion ever conceived.

The speculative but serious cosmology is described as a "pretty fantastic possibility" even by its lead author, Robert Caldwell of Dartmouth University. It explains one possible outcome for solid astronomical observations made in the late 1990s -- that the universe is expanding at an ever-increasing pace, and that something unknown is vacuuming everything outward.

The question Caldwell and his colleagues posed is, what would happen if the rate of acceleration increased?

Their answer is that the eventual, phenomenal pace would overwhelm the normal, trusted effects of gravity right down to the local level. Even the nuclear forces that bind things in the subatomic world will cease to be effective.

"The expansion becomes so fast that it literally rips apart all bound objects," Caldwell explained in a telephone interview. "It rips apart clusters of galaxies. It rips apart stars. It rips apart planets and solar systems. And it eventually rips apart all matter."

He calls it, as you might guess, the Big Rip.

The standard view

Driving the known acceleration of the universe's expansion is a mysterious thing is called dark energy, thought of by scientists as anti-gravity working over large distances.

Conventional wisdom holds that the acceleration will proceed at a constant rate, akin to a car that moves 10 mph faster with each mile traveled. With nothing to cap the acceleration, all galaxies will eventually recede from one another at the speed of light, leaving each galaxy alone in a cold, dark universe within 100 billion years. We would not be able to see any galaxies outside our Milky Way, even with the most powerful telescopes.

That's the conventional view, remarkable as it sounds.

The Big Rip theory has dark energy's prowess increasing with time, until it's an out-of-control phantom energy. Think of our car accelerating an additional 10 mph every half mile, then every hundred yards, then every foot.

Before long, the bumpers are bound to fly off. Sooner or later, our hypothetical engine will come apart, regardless of how much we spend on motor oil.

Countdown to demise

Other theorists who have reviewed the Big Rip theory are not yet sold on the idea. Meanwhile, Caldwell's team has provided a precise countdown to total demise. The projected end is, reassuringly, 20 billion years away. If our species survives the next 19 billion years (and there are serious doubts about this, given our Sun's projected fate) here are some signs that scientists of the future will want to look for.

• A billion years before the end, all galaxies will have receded so far and so fast from our own as to be erased from the sky, as in no longer visible.
• When the Milky Way begins to fly apart, there are 60 million years left.
• Planets in our solar system will start to wing away from the Sun three months before the end of time.
• When Earth explodes, the end is momentarily near.

At this point, there is still a short interval before atoms and even their nuclei break apart. "There's about 30 minutes left," Caldwell said, "But it's not quality time."

And then what? Does the universe recycle itself? Is there something after nothing?

"We're not sure what happens after that," Caldwell says. "On the face of it, it would look like time ends."

The first explosion

Caldwell's study had humble beginnings. He and his colleagues, Marc Kamionkowski and Nevin Weinberg at Caltech, were considering how a sphere of matter collapses under its own weight to form a galaxy. In computer models, they tweaked with the dark energy factor and found that too much of it would actually prevent the sphere from collapsing. In extreme cases, the sphere exploded.

"That was our hint that there was something really unusual going on," Caldwell said.

It wasn't long ago, just before the accelerated expansion was discovered, that many cosmologists believed the universe might reverse course, that normal gravity would win, and that everything would fall back in a Big Crunch. More recently, solid observational data has all but assured the infinite-expansion model and the cold, dark, never-ending end.

The Caldwell group decided there might be a third possibility, leading to their new paper, which has been submitted to thePhysical Review.

But there are many unknowns. It is not clear if the dark energy driving expansion is a force not currently described by physics, or if it is merely a different manifestation of gravity over huge distances. The repulsion could be a response to dark matter, unseen stuff that is known to comprise 23 percent of the universe, based on firm observations.

Dark matter has unknown properties, and it may be related to dark energy, Caldwell said. He notes that even Einstein considered that gravity might work repulsively, in a manner consistent with his theory of general relativity.

Dark energy, being quantified only recently, tends to be discussed as some strange new force, in addition to the four fundamental forces: gravity, electromagnetism, and the strong and weak nuclear forces that govern atoms. But the repulsion is possibly just the way gravity behaves in the presence of dark energy, Caldwell said. In that sense, it is not a new force.

Cautious reception

To turn dark energy into destructive phantom energy, Caldwell and his colleagues had to play around with a thing called the cosmological constant, a mathematical fix that Einstein applied to general relativity. Einstein later called it his greatest mistake, when Edwin Hubble found in the 1920s that the universe was expanding (seven decades later, that expansion would be seen accelerating).

The cosmological constant has been recently revived. Attempts to describe dark energy differ in how the density of dark energy varies with time. In some models, the density decreases slowly. For the cosmological constant, the density is a constant. For phantom energy, it must grow with time.

"We considered a more exotic form of dark energy which was more repulsive," as Caldwell explains is.

Abraham Loeb, a theoretician at the Harvard-Smithsonian Center for Astrophysics, has quantified the lonely effects of a forever-expanding universe. Loeb stands by that scenario, but he said Caldwell's idea is nonetheless interesting to explore.

"I think it's a logical possibility," Loeb told SPACE.com. But he cautioned that altering the cosmological constant goes against current consensus.

"If I had to place a bet, I would bet in favor of the standard cosmological constant," Loeb said.

Sci-fi to reality

If Caldwell's team is right, cosmology would undergo a revolution. Sci-fi ideas like wormholes and time travel might suddenly enter the realm of hard science. All of this could sort itself out pretty soon, Caldwell believes. Observations over the next few years may actually show whether his phantom energy is possible.

"Who knows if it is right or wrong," Caldwell said of his theory. "I think we'll find out pretty soon."

In fact, recent observations from NASA's WMAP space probe have pinned down the physics of the universe with surprising accuracy. A little wiggle room remains for the cosmological constant. Yet more WMAP data are expected over the next four years. Other missions, including one called the Supernova Acceleration Probe (SNAP), could provide answers, Caldwell said.

Even if the Big Rip is a big bust, there's no guarantee of a pleasant ending.

Alternate final chapter

Paul Steinhardt, a Princeton University physicist, is, like Caldwell and Loeb, no stranger to strange ideas. Steinhardt advocates a cyclical universe, one that has no beginning or end but which instead is constantly starting over again.

Steinhardt theorizes within the generally accepted standards of the cosmological constant. He said the Big Rip is more exotic than most ideas but still conceivable, a projected possible result that is "straightforward and obvious for cosmologists."

Yet there is another entirely different possibility for the final moments of time as we know it.

In a theory put forth two years ago by Steinhardt and his colleagues, our universe is but a membrane, or brane, floating in a five-dimensional space. It is destined to collide dramatically with another brane. The idea, labeled the Ekpyrotic Universe, would replace portions of the Big Bang scenario while sticking to the presently accepted estimates of acceleration.

"Lest you get too optimistic, galaxies are destroyed in a far more violent way," Steinhardt said of the brane scenario. "They are vaporized at the next 'bang' -- the collision between branes so, you either rip them apart or you vaporize them."

Black Hole Knocked Off Axis By Galaxy Collision

The discovery of a giant, spinning black hole that has been knocked off its axis twice has led astronomers to suggest that a violent galaxy collision caused the strange cosmic behavior.

"We think that this black hole has quite a history," said astronomer Christopher Reynolds of the University of Maryland, a co-author in the black hole study. "Not once, but twice, something has caused this black hole to change its spin axis."

In this new study, scientists detected the change in the black hole's axis using the latest data from NASA's Chandra X-ray Observatory. The likely cuprit: A catastrophic collision between two galaxies.The galactic smash-up is thought to have altered the axis of the spinning black hole. But unlike another recent study, in which colliding galaxies may have created recoiling black holes, this particular black hole was not moved by the crash – only its spin changed.

Askew black hole

The black hole find emerged from extensive observations by astronomers of a galaxy known as 4C +00.58, which is located approximately 780 million light-years from Earth. Like many galaxies, a supermassive black hole resides at the heart of 4C +00.58.

This particular black hole is actively pulling in large amounts of gas, which is swirling around and forming a disk around the object. The jumbled magnetic fields within the disk generate strong electromagnetic forces that propel some of the gas away from the disk at high speed, producing bursts of radio jets.

But here's where it gets strange.

A radio image of 4C +00.58 shows a bright pair of jets that point from left to right, and a fainter, more distant line of radio emission that runs in a completely different direction. Scientists classify this type of galaxy as "X-shaped," because of the outline of their radio emission.

"We think this is the best evidence ever seen for a black hole having been jerked around like this," said the study's lead author Edmund Hodges-Kluck of the University of Maryland in College Park, Md. "We're not exactly sure what caused this behavior, but it was probably triggered by a collision between two galaxies."

Black hole weirdness

The new observations allowed astronomers to infer the possible mechanisms behind the 4C +00.58 system, and possibly others that may be similar.

Chandra's X-ray image revealed four separate cavities around the supermassive black hole. These cavities come in pairs: one in the top-right and bottom-left, and another in the top-left and bottom-right.

Based on the orientation of the radio jets, the complicated geometry that was revealed by the Chandra image could explain what happened to the system's black hole, as well as the galaxy itself.

The research is detailed in a recent edition of the Astrophysical Journal Letters.

So how did it happen?

Hodges-Kluck and his colleagues think that the original spin axis of the black hole ran along a diagonal line from top-right to bottom-left. Following a collision with a smaller galaxy, a jet powered by the black hole then ignited, blowing away surrounding gas to form cavities in the hot gas to the top-right and bottom-left.

In this scenario, since the gas falling onto the black hole was not aligned with the black hole's spin, the axis of the black hole rapidly changed direction, causing the jets to point in a roughly top-left to bottom-right orientation. This, in turn, created other cavities in the hot gas, and radio emissions in this new direction.

Finally, either a merger of the two central black holes from the colliding galaxies, or more gas falling onto the black hole, caused the spin axis to get moved to its present direction, which is roughly left to right.

These types of changes to the angle of the spin of supermassive black holes have previously been suggested as a way of explaining X-shaped radio galaxies. But so far, no convincing case has been made for any individual object – perhaps until now.

"If we're right, our work shows that jets and cavities are like cosmic fossils that help trace the merger history of an active supermassive black hole and the galaxy it lives in," said Hodges-Kluck. "If even a fraction of X-shaped radio galaxies are produced by such "spin-flips", then their frequency may be important for estimating the detection rates with gravitational radiation missions."

Source Space.com

Superfast Star Shot Out of Milky Way

A super-hot blue star hurtling through space has been shot completely out of the Milky Way, new Hubble Space Telescope photos reveal.

The star is streaking across space at a blistering speed of 1.6 million mph (2.5 million kph) – three times faster than our sun's orbital velocity in the Milky Way. Hubble observations confirm that the stellar speedster hails from the Milky Way's core, settling some confusion over where it originally called home.Astronomers think the star is a survivor from a triple-star system that traveled through the bustling center of our Milky Way galaxy 100 million years ago, but made the perilous mistake of wandering too close to the galaxy's giant black hole, which captured one of the stars and flung the other two out of the Milky Way. The two ejected stars then merged to form a super-hot, blue star.

While it may seem a little farfetched, astronomers using NASA'sHubble Space Telescope say it is the most likely scenario for the so-called hypervelocity star, known as HE 0437-5439, one of the fastest ever detected.

"Using Hubble, we can for the first time trace back to where the star comes from by measuring the star's direction of motion on the sky," said astronomer Warren Brown of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of the study and a member of the Hubble team that observed the star. "Its motion points directly from the Milky Way center. These exiled stars are rare in the Milky Way's population of 100 billion stars. For every 100 million stars in the galaxy lurks one hypervelocity star."

Since the first discovery in 2005, astronomers have found 16 hypervelocity stars, most of which are thought to be exiles from the heart of our galaxy. But, the new Hubble result is the first direct observation that links a high-flying star to a galactic center origin.

What this tells us

The movements of these breakneck stars could reveal the shape of thedark matter distribution surrounding our galaxy.

"Studying these stars could provide more clues about the nature of some of the universe's unseen mass, and it could help astronomers better understand how galaxies form," said Oleg Gnedin of the University of Michigan in Ann Arbor. "Dark matter's gravitational pull is measured by the shape of the hyperfast stars' trajectories out of the Milky Way."

The HE 0437-5439 stellar outcast is already trekking deep in the Milky Way's distant outskirts, high above the galaxy's disk, about 200,000 light-years from the center. By comparison, the diameter of the Milky Way's disk is approximately 100,000 light-years.

Astronomers used Hubble data to measure the runaway star's direction of motion and determine the Milky Way's core as its starting point. Brown and Gnedin's team then calculated how fast the star had to have been ejected in order to reach its current location.

"The star is traveling at an absurd velocity, twice as much as the star needs to escape the galaxy's gravitational field," said Brown, who discovered the first unbound, hypervelocity star in 2005. "There is no star that travels that quickly under normal circumstances – something exotic has to happen."

But wait, there's more

After studying the star, researchers noticed that some of the calculations did not seem to add up.

Based on the speed and position of HE 0437-5439, the star would have to be 100 million years old to have journeyed such a distance from the Milky Way's core. Yet its mass – nine times that of our sun – and blue color mean that it should have burned out after only 20 million years – far shorter than the transit time it took to get to its current location.

The most likely explanation for the star's blue color and extreme speed is that it was part of a triple-star system that was involved in an ill-fated encounter with the Milky Way's monster black hole.

This concept for imparting an escape velocity on stars was first proposed in 1988. The theory predicted that the Milky Way's black hole should eject a star about once every 100,000 years.

Brown suggests that the triple-star system contained a pair of closely orbiting stars and a third outer member that was also gravitationally tied to the group. The close encounter enabled the black hole to wrench the outer star away from the tight binary system.

The doomed star's momentum was then transferred to the stellar twosome, boosting the duo to escape velocity from the galaxy. As the pair rocketed away, they carried on with normal stellar evolution.

The more massive companion star evolved more quickly, puffing up to become a red giant and enveloping its partner in the process. The two stars spiraled together, merging into one superstar – a blue straggler.

"While the blue straggler story may seem odd, you do see them in the Milky Way, and most stars are in multiple systems," Brown said.

The mysterious blue straggler

This vagabond star has puzzled astronomers since its discovery in 2005 by the Hamburg/European Southern Observatory sky survey.

Astronomers had proposed two possibilities to solve the age problem. The star either defied the normal aging process by becoming a blue straggler, or it was flung out of the Large Magellanic Cloud, a neighboring galaxy.

In 2008, a team of astronomers thought they had solved the mystery. They found a match between the exiled star's chemical makeup and the characteristics of other stars in the Large Magellanic Cloud.

The rogue star's position is also close to the neighboring galaxy – only 65,000 light-years away. The new Hubble result now settles the debate over the star's birthplace.

Astronomers using the sharp vision of Hubble's Advanced Camera for Surveys were able to make two separate observations of the wayward star 3 1/2 years apart. Team member Jay Anderson of the Space Telescope Science Institute in Baltimore, Md., developed a technique that measures the star's position relative to each of 11 distant background galaxies, which form a frame of reference.

Anderson then compared the star's position in images taken in 2006 with those taken in 2009 in order to calculate how far the star moved in relation to the background galaxies. The star appeared to move, but only by 0.04 of a pixel (picture element) against the background.

"Hubble excels with this type of measurement," said Anderson. "This observation would be challenging to do from the ground."

The team is now trying to determine the homes of four other unbound stars, all located on the fringes of the Milky Way galaxy.

"We are targeting massive 'B' stars, like HE 0437-5439," said Brown, who has discovered 14 of the 16 known hypervelocity stars. "These stars shouldn't live long enough to reach the distant outskirts of the Milky Way, so we shouldn't expect to find them there. The density of stars in the outer region is much less than in the core, so we have a better chance to find these unusual objects."

Sourced Space.com.

There are an estimated 50 thousand million galaxies in the universe, with the typical galaxy containing 50 thousand million to 100 thousand million stars. It is estimated that there are 10²² stars in total in the universe.

Recipe for a Universe

Take a massive explosion to create plenty of stardust and a raging heat. Simmer for an eternity in a background of cosmic microwaves. Let the ingredients congeal and leave to cool and serve cold with cultures of tiny organisms 13.7 billion years later.

To understand the basic ingredients and the ‘cooking conditions’ of the cosmos, from the beginning of time to the present day, particle physicists have to try and reverse-engineer the ‘dish’ of the Universe. Within the complex concoction, cryptic clues hide the instructions for the cosmic recipe.