Exoplanet List to Smash Over 1000?

From Scientific American:

Thirty million kilometers away, trailing the pale blue dot that is Earth as it orbits the sun, is a spacecraft designed to find some of the countless other pale blue dots that may speckle the galaxy. NASA launched this spacecraft, known as Kepler, in 2009 to take a census of Earth-like planets in the hopes of figuring out how common—or how rare—are the conditions under which life has thrived here.

Just over halfway into that 3.5-year campaign, Kepler has not been on the job long enough to conclusively identify any habitable worlds, but its discoveries are growing ever more tantalizing. In a field where small is good—small meaning less like Jupiter and more like Earth—the latest batch of planets netted by the space observatory includes five of the eight smallest worlds now known outside the solar system. All five of the new extrasolar planets, or exoplanets, as well as one more world whose properties are not yet fully understood, orbit a sunlike star called Kepler 11, some 2,000 light-years away. A group of researchers announced the discovery of the six-planet Kepler 11 system in the February 3 issue of Nature. (Scientific American is part of Nature Publishing Group.)

Almost simultaneously, the Kepler team was preparing a list of more than 1,200 additional objects the spacecraft has located that may also be planets. "We have a huge number of candidates," says Kepler's principal investigator, Bill Borucki of NASA Ames Research Center, Moffett Field, Calif. "It's very exhilarating," says Borucki, who first put forth the idea for Kepler in 1984 and proposed the concept several times before getting NASA's approval and funding. The data on the numerous candidates are somewhat preliminary and require validation, but a new analysis by a pair of astrophysicists at the California Institute of Technology suggests that the percentage of false positives among Kepler's candidate planets may be less than 10 percent.

If that is the case, then Kepler is well on its way to vastly augmenting the roster of known exoplanets, of which there are now 500 or so, and may have already gotten a whiff of several potentially habitable worlds. "We have 54 planets in the habitable zone of their stars," Borucki says, referring to the temperate orbital zone around a star that would allow for the existence of liquid water on a planet. "One of them is 0.9 times the radius of the Earth, and four of them are less than two Earth radii." Any of those would be the most Earth-like world ever detected outside the solar system. What is more, some of the larger, more Jupiter-like planets Kepler is sniffing at in the habitable zone might have moons, and some of those satellites would themselves be potentially habitable. "It's sort of awesome," Borucki says of Kepler's haul. "The implications are that there are an awful lot of planets out there."

A Wealth of Worlds: Kepler Spacecraft Finds 6 New Exoplanets and Hints at 1,200 More
John Matson
February 2, 2011
http://www.scientificamerican.com/article.cfm?id=kepler-11-thousands-extrasolar-planets

Nearby planet in perfect position to foster life

http://www.salon.com/news/feature/2010/09/29/us_sci_new_earths/index.html

Wednesday, Sep 29, 2010
Nearby planet in perfect position to foster life
Belongs in "Goldilocks zone," according to National Science Foundation: Not too hot and not too cold
Associated Press

Astronomers say they have for the first time clearly spotted a planet beyond our solar system in what is sometimes called the Goldilocks zone -- where key conditions for life to exist are just right.

Not too far from its star, not too close. So it's not too hot, not too cold for liquid water and life. It's just right. Just like Earth

And it is in our galactic neighborhood. That suggests that plenty of Earth-like planets circle other stars and maybe that we are not alone.

The National Science Foundation announced the finding Wednesday. The planet circles a star that is 120 trillion miles away, which is closer than most stars. It is about three times the mass of Earth.

Was the Moon created by a nuclear explosion?

http://www.dailymail.co.uk/sciencetech/article-1246872/Was-moon-created-nuclear-explosion-Earth.html

Was the Moon created by a nuclear explosion on Earth?
By Daily Mail Reporter
29th January 2010

How the Moon was created and came to orbit the Earth has long puzzled scientists.

The most commonly held theory is that when the solar system was first formed, an object collided with Earth, knocking off a chunk of rock that fell into orbit around it.

But now two scientists have come up with a new explanation. They believe the Moon did not break away from the Earth because of an impact or an explosion in space, but because of a nuclear explosion on Earth itself.

Their idea is based on the fission theory which was first outlined in the 19th century.

The fission theory suggested that the Earth and Moon were both created out of the same blob of spinning molten rock - with a part becoming separated which later became the moon.

However, aside from an impact, scientists couldn't explain how the blob which became the moon spun off.

Rob de Meijer at University of the Western Cape and Wim van Westrenen at VU University in Amsterdam believe the Moon was blasted out of the Earth by a nuclear explosion on our planet.

In their research paper, 'An alternative hypothesis for the origin of the Moon', they explain that if the moon had been separated from the Earth by an impacting external force, the moon would be composed of whatever knocked into it and the Earth.
'Models of solar system evolution show that it is highly unlikely for the chemical composition of the Earth and impactor to be identical,' they state.

Yet recent lunar samples show that the moon is almost identical in chemical composition to the Earth - suggesting there was no impactor involved.

'A more likely possibility for the large degree of compositional similarity... is that the moon derives directly from terrestrial material,' the research paper states.

They believe that the energy that caused the moon to break into orbit around Earth was 'supplied by a supercritical georeactor in Earth’s core-mantle boundary producing sufficient heat to vaporize and eject part of the bulk silicate earth'.
Clay Dillow from Popular Science supports the theory. He states: 'According to their explanation, the centrifugal forces on Earth concentrated heavier elements like uranium and thorium near the surface around the equatorial plane.

'Enough of these elements in high enough concentrations could set off a runaway nuclear chain reaction, similar to the kind that cause nuke plant meltdowns.

'In this way, a natural-born nuclear georeactor was pushed to supercritical levels and: BOOM! The moon was cleaved from the Earth and rocketed into orbit by a massive nuclear explosion.

'It’s a tough theory to test, but we do know that nuclear georeactors existed, their legacy left behind in the uranium we mine from the Earth today. '

De Meijer and van Westrenan conclude that proving their theories will depend on future moon missions returning lunar samples from greater depths.

Space head: Russia may send spacecraft to asteroid

http://news.yahoo.com/s/ap/20091230/ap_on_re_eu/eu_russia_asteroid_encounter

Space head: Russia may send spacecraft to asteroid
Vladimir Isachenkov, Associated Press Writer
Wed Dec 30, 2009

MOSCOW – Russia's space chief said Wednesday his agency will consider sending a spacecraft to a large asteroid to knock it off its path and prevent a possible collision with Earth.

Anatoly Perminov said the space agency will hold a meeting soon to assess a mission to Apophis, telling Golos Rossii radio that it would invite NASA, the European Space Agency, the Chinese space agency and others to join the project once it is finalized.

When the 270-meter (885-foot) asteroid was first discovered in 2004, astronomers estimated the chances of it smashing into Earth in its first flyby in 2029 were as high as 1-in-37.

Further studies ruled out the possibility of an impact in 2029, when the asteroid is expected to come no closer than 18,300 miles (29,450 kilometers) above Earth's surface, but they indicated a small possibility of a hit on subsequent encounters.

In October, NASA lowered the odds that Apophis could hit Earth in 2036 from a 1-in-45,000 as earlier thought to a 1-in-250,000 chance after researchers recalculated the asteroid's path. It said another close encounter in 2068 will involve a 1-in-330,000 chance of impact.

Scientists have long theorized about asteroid deflection strategies. Some have proposed sending a probe to circle around a dangerous asteroid to gradually change its trajectory. Others suggested sending a spacecraft to collide with the asteroid and alter its momentum, or using nuclear weapons to hit it.

Without mentioning NASA findings, Perminov said that he heard from a scientist that Apophis is getting closer and may hit the planet. "I don't remember exactly, but it seems to me it could hit the Earth by 2032," Perminov said.

He wouldn't disclose any details of the project, saying they still need to be worked out. But he said the mission wouldn't require any nuclear explosions.

Hollywood action films "Deep Impact" and "Armageddon," have featured space missions scrambling to avoid catastrophic collisions. In both movies space crews use nuclear bombs in an attempt to prevent collisions.

"Calculations show that it's possible to create a special purpose spacecraft within the time we have, which would help avoid the collision without destroying it (the asteroid) and without detonating any nuclear charges," Perminov said. "The threat of collision can be averted."

"People's lives are at stake. We should pay several hundred million dollars and build a system that would allow to prevent a collision, rather than sit and wait for it to happen and kill hundreds of thousands of people," he added.

Boris Shustov, the director of the Institute of Astronomy under the Russian Academy of Sciences, hailed Perminov's statement as a signal that officials had come to recognize the danger posed by asteroids.

"Apophis is just a symbolic example, there are many other dangerous objects we know little about," he said, according to RIA Novosti news agency.

Environmentalists hail Earth Hour as a big success

http://www.google.com/hostednews/ap/article/ALeqM5jTPC5ic6tJh9PiHscwgOANkJ17-wD977R3400

Environmentalists hail Earth Hour as a big success
By VANESSA GERA
3-29-9

BONN, Germany (AP) — For environmental activists, the message was clear: Earth Hour was a huge success.

Now they say nations have a mandate to tackle climate change.

"The world said yes to climate action, now governments must follow," the World Wildlife Fund (WWF) said Sunday, a day after hundreds of millions of people worldwide followed its call to turn off lights for a full hour.

From an Antarctic research base and the Great Pyramids of Egypt, from the Colosseum in Rome to the Empire State building in New York, illuminated patches of the globe went dark Saturday night to highlight the threat of climate change. Time zone by time zone, nearly 4,000 cities and towns in 88 countries dimmed nonessential lights from 8:30 p.m. to 9:30 p.m.

WWF called the event, which began in Australia in 2007 and grew last year to 400 cities worldwide, "the world's first-ever global vote about the future of our planet."

The United Nations' top climate official, Yvo de Boer, called the event a clear sign that the world wants negotiators seeking a climate change agreement to set an ambitious course to fight global warming.

Talks in Bonn this week are the latest round in an effort to craft a deal to control emissions of the heat-trapping gases responsible for global warming. They are due to culminate in Copenhagen this December.

"Earth Hour was probably the largest public demonstration on climate change ever," de Boer told delegates from 175 nations. "Its aim was to tell every government representative to seal a deal in Copenhagen. The world's concerned citizens have given the negotiations an additional and very clear mandate."

Earth Hour officially began when the Chatham Islands, 500 miles (800 kilometers) east of New Zealand, switched off its diesel generators. It moved on through Asia, Europe and then crossed the Atlantic to North and South America.

"Earth Hour has always been a positive campaign," said Earth Hour executive director Andy Ridley. "It's always around street parties, not street protests, it's the idea of hope, not despair. And I think that's something that's been incredibly important this year because there is so much despair around."

Associated Press writers around the world contributed to this report.

On the Net:

Earth Hour: http://www.earthhour.org
U.N. Secretary-General Ban Ki-moon's Earth Hour video: http://sn.im/enqwn

President 'has four years to save Earth'

http://www.guardian.co.uk/environment/2009/jan/18/jim-hansen-obama

President 'has four years to save Earth'
US must take the lead to avert eco-disaster
Robin McKie in New York
The Observer
Sunday 18 January 2009

Barack Obama has only four years to save the world. That is the stark assessment of Nasa scientist and leading climate expert Jim Hansen who last week warned only urgent action by the new president could halt the devastating climate change that now threatens Earth. Crucially, that action will have to be taken within Obama's first administration, he added.

Soaring carbon emissions are already causing ice-cap melting and threaten to trigger global flooding, widespread species loss and major disruptions of weather patterns in the near future. "We cannot afford to put off change any longer," said Hansen. "We have to get on a new path within this new administration. We have only four years left for Obama to set an example to the rest of the world. America must take the lead."

Hansen said current carbon levels in the atmosphere were already too high to prevent runaway greenhouse warming. Yet the levels are still rising despite all the efforts of politicians and scientists.

Only the US now had the political muscle to lead the world and halt the rise, Hansen said. Having refused to recognise that global warming posed any risk at all over the past eight years, the US now had to take a lead as the world's greatest carbon emitter and the planet's largest economy. Cap-and-trade schemes, in which emission permits are bought and sold, have failed, he said, and must now be replaced by a carbon tax that will imposed on all producers of fossil fuels. At the same time, there must be a moratorium on new power plants that burn coal - the world's worst carbon emitter.

Hansen - head of the Goddard Institute of Space Studies and winner of the WWF's top conservation award - first warned Earth was in danger from climate change in 1988 and has been the victim of several unsuccessful attempts by the White House administration of George Bush to silence his views.

Hansen's institute monitors temperature fluctuations at thousands of sites round the world, data that has led him to conclude that most estimates of sea level rises triggered by rising atmospheric temperatures are too low and too conservative. For example, the Intergovernmental Panel on Climate Change says a rise of between 20cm and 60cm can be expected by the end of the century.

However, Hansen said feedbacks in the climate system are already accelerating ice melt and are threatening to lead to the collapse of ice sheets. Sea-level rises will therefore be far greater - a claim backed last week by a group of British, Danish and Finnish scientists who said studies of past variations in climate indicate that a far more likely figure for sea-level rise will be about 1.4 metres, enough to cause devastating flooding of many of the world's major cities and of low-lying areas of Holland, Bangladesh and other nations.

As a result of his fears about sea-level rise, Hansen said he had pressed both Britain's Royal Society and the US National Academy of Sciences to carry out an urgent investigation of the state of the planet's ice-caps. However, nothing had come of his proposals. The first task of Obama's new climate office should therefore be to order such a probe "as a matter of urgency", Hansen added.

UN is told that Earth needs an asteroid shield

http://www.guardian.co.uk/science/2008/dec/07/space-technology-asteroid-shield

UN is told that Earth needs an asteroid shield
Scientists call for £68m a year to detect danger, and more for spacecraft to defend against it
Robin McKie, science editor
The Observer, Sunday December 7 2008

A group of the world's leading scientists has urged the United Nations to establish an international network to search the skies for asteroids on a collision course with Earth. The spaceguard system would also be responsible for deploying spacecraft that could destroy or deflect incoming objects.

The group - which includes the Royal Society president Lord Rees and environmentalist Crispin Tickell - said that the UN needed to act as a matter of urgency. Although an asteroid collision with the planet is a relatively remote risk, the consequences of a strike would be devastating.

An asteroid that struck the Earth 65 million years ago wiped out the dinosaurs and 70 per cent of the species then living on the planet. The destruction of the Tunguska region of Siberia in 1908 is known to have been caused by the impact of a large extraterrestrial object.

'The international community must begin work now on forging three impact prevention elements - warning, deflection technology and a decision-making process - into an effective defence against a future collision,' said the International Panel on Asteroid Threat Mitigation, which is chaired by former American astronaut Russell Schweickart. The panel made its presentation at the UN's building in Vienna.

The risk of a significantly sized asteroid - defined by the panel as being more than 45 metres in diameter - striking the Earth has been calculated at two or three such events every 1,000 years, a rare occurrence, though such a collision would dwarf all other natural disasters in recent history.

The panel added that developments in telescope design mean that, by 2020, it should be possible to pinpoint about 500,000 asteroids in orbit round the Sun and study their movements. Of these, several dozen will be revealed to pose threats to Earth, the panel added.

However, the group warned it would be impossible to predict exactly which of these 'at-risk' asteroids would actually strike until it was very close to our planet. By then, it would be too late to take action.

As a result, the panel said it would be necessary to launch missions to deflect or destroy asteroids that have only a one in 10, or even a one in 100, risk of hitting our planet. 'Over the next 10 to 15 years, the process of discovering asteroids will likely identify dozens of new objects threatening enough that they will require proactive decisions by the United Nations,' the report added. In addition, such missions will have to be launched well ahead of a predicted impact, so that slight deflections by spaceships can induce major changes in an asteroid's paths years later. The world will not be able to rely on Bruce Willis saving it from an asteroid at the last minute as he does in Armageddon, in other words. Considerable planning and forethought will be needed.

Funding such missions will therefore require far greater investment than is currently being made by international authorities. At present, about $4m (£2.7m) a year is spent by Nasa on asteroid detection, while the European Space Agency's planned mission to study the asteroid Apophis - which astronomers calculate has a 1 in 45,000 chance of striking the Earth this century - is likely to be a modest project costing only a few tens of millions of dollars.

By contrast, any effective protection system will require funding of about $100m (£68m) a year to provide a full survey of the skies, combined with investment in spacecraft that can reach an asteroid and then deflect it. This would be achieved either by crashing the spacecraft on to the asteroid or by triggering a nuclear explosion in space.

However, the cost of such missions should not be used as an excuse for failing to act, added the panel. 'We are no longer passive victims of the impact process,' it concluded. 'We cannot shirk the responsibility.'

Stars with Rocky Planets May Be Common

http://blog.wired.com/wiredscience/2008/02/researchers-sta.html

Researchers: Stars with Rocky Planets May Be Common
By John Borland February 18, 2008
Categories: Space

For the last several years, scientists have been discovering new planets elsewhere in the universe at an astonishing rate. Now a group of researchers who have surveyed a large group of stars similar to our own Sun say that potentially life-supporting rocky planets may in fact be extremely common in the Milky Way, circling anywhere from 20 percent to 60 percent of Sun-like stars.

Using the Spitzer Space Telescope, the researchers looked for signs of hot dust at distances plausible for planet formation around various stars, categorized by age.

They found that warm dust at that distance was relatively common around stars that were 10 million to 20 million years old, but that it fell off almost entirely by the time stars were about 300 million years old.

That's about the right time scale to correspond with the time the Earth and other planets are believed to have formed slowly through the collision of smaller bodes, out of the Sun's own dust cloud. Here's University of Arizona astronomer Michael Meyer, who led the study:

"We don't often see warm-dust around stars older than 300 million years. The frequency just drops off. That's comparable to the time scales thought to span the formation and dynamical evolution of our own solar system," he added. "Theoretical models and meteoritic data suggest that Earth formed over 10 to 50 million years from collisions between smaller bodies."

A separate study found dust that some believe is attributable to the process of planet formation around stars that were just 10 million to 30 million years old.

The data can be interpreted different ways. At worst, it appears to show that at least one out of five Sun-like stars has the potential for forming rocky planets, they said. An optimistic interpretation might be that some massive discs of dust would form planets more quickly – and in that case, up to 62 percent of stars could be planet-forming.

But either way, the data seems to show there are plenty of other planets out there.

A paper on the conclusions appeared in the Feb. 1 issue of Astrophysical Journal Letters

New 'super-Earth' found in space

http://news.bbc.co.uk/2/hi/science/nature/6589157.stm

New 'super-Earth' found in space
Wednesday, 25 April 2007

Astronomers have found the most Earth-like planet outside our Solar System to date, a world which could have water running on its surface.

The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra.

Scientists made the discovery using the Eso 3.6m Telescope in Chile.

They say the benign temperatures on the planet mean any water there could exist in liquid form, and this raises the chances it could also harbour life.

"We have estimated that the mean temperature of this 'super-Earth' lies between 0 and 40 degrees Celsius, and water would thus be liquid," explained Stephane Udry of the Geneva Observatory, lead author of the scientific paper reporting the result.

'Is there life anywhere else?' is a fundamental question we all ask
Alison Boyle
London Science Museum

"Moreover, its radius should be only 1.5 times the Earth's radius, and models predict that the planet should be either rocky - like our Earth - or covered with oceans."
Xavier Delfosse, a member of the team from Grenoble University, added: "Liquid water is critical to life as we know it."

He believes the planet may now become a very important target for future space missions dedicated to the search for extra-terrestrial life.

These missions will put telescopes in space that can discern the tell-tale light "signatures" that might be associated with biological processes.

The observatories would seek to identify trace atmospheric gases such as methane, and even markers for chlorophyll, the pigment in Earth plants that plays a critical role in photosynthesis.

'Indirect' detection

The exoplanet - as astronomers call planets around a star other than the Sun - is the smallest yet found, and has been given the designation Gliese 581 c.

It completes a full orbit of its parent star in just 13 days.

EXOPLANET GLIESE 581 C
Mass: Five times Earth's mass
Orbit: 13 days
Temperature: 0C - 40C
Distance: 20.5 light years
Constellation: Libra

Indeed, it is 14 times closer to its star than the Earth is to our Sun.

However, given that the host star is smaller and colder than the Sun - and thus less luminous - the planet nevertheless lies in the "habitable zone", the region around a star where water could be liquid.

Gliese 581 c was identified at the European Southern Observatory (Eso) facility at La Silla in the Atacama Desert.

To make their discovery, researchers used a very sensitive instrument that can measure tiny changes in the velocity of a star as it experiences the gravitational tug of a nearby planet.

Astronomers are stuck with such indirect methods of detection because current telescope technology struggles to image very distant and faint objects - especially when they orbit close to the glare of a star.

The Gliese 581 system has now yielded three planets: the new super-Earth, a 15 Earth-mass planet (Gliese 581 b) orbiting even closer to the parent star, and an eight Earth-mass planet that lies further out (Gliese 581 d).

The latest discovery has created tremendous excitement among scientists.

Of the more than 200 exoplanets so far discovered, a great many are Jupiter-like gas giants that experience blazing temperatures because they orbit close in to much hotter stars.

The Gliese 581 super-Earth is in what scientists also sometimes call the "Goldilocks Zone", where temperatures "are just right" for life to have a chance to exist.

Commenting on the discovery, Alison Boyle, the curator of astronomy at London's Science Museum, said: "Of all the planets we've found around other stars, this is the one that looks as though it might have the right ingredients for life.

"It's 20 light-years away and so we won't be going there anytime soon, but with new kinds of propulsion technology that could change in the future. And obviously we'll be training some powerful telescopes on it to see what we can see," she told BBC News.

"'Is there life anywhere else?' is a fundamental question we all ask."

Professor Glenn White at the Rutherford Appleton Laboratory is helping to develop the European Space Agency's Darwin mission, which will scan the nearby Universe, looking for signs of life on Earth-like planets. He said: "This is an important step in the search for true Earth-like exoplanets.

"As the methods become more and more refined, astronomers are narrowing in on the ultimate goal - the detection of a true Earth-like planet elsewhere.

"Obviously this newly discovered planet and its companions in the Gliese 581 system will become prominent targets for missions like Esa's Darwin and Nasa's Terrestrial planet Finder when they fly in about a decade."

The discovery is reported in the journal Astronomy & Astrophysics.

Distant space collision meant doom for dinosaurs

http://news.yahoo.com/s/nm/20070905/sc_nm/asteroid_dinosaurs_dc_1

Distant space collision meant doom for dinosaurs
By Will Dunham
Wed Sep 5, 2007

A collision 160 million years ago of two asteroids orbiting between Mars and Jupiter sent many big rock chunks hurtling toward Earth, including the one that zapped the dinosaurs, scientists said on Wednesday.

Their research offered an explanation for the cause of one of the most momentous events in the history of life on Earth -- a six-mile-wide (10-km-wide) meteorite striking Mexico's Yucatan peninsula 65 million years ago.

That catastrophe eliminated the dinosaurs, which had flourished for about 165 million years, and many other life forms, and paved the way for mammals to dominate the Earth and the eventual rise of humankind, many scientists believe.

The impact is thought to have triggered a worldwide environmental cataclysm, expelling vast quantities of rock and dust into the sky, unleashing giant tsunamis, sparking global wildfires and leaving Earth shrouded in darkness for years.

U.S. and Czech researchers used computer simulations to calculate that there was a 90 percent probability that the collision of two asteroids -- one about 105 miles wide and one about 40 miles wide -- was the event that precipitated the Earthly disaster.

The collision occurred in the asteroid belt, a collection of big and small rocks orbiting the sun about 100 million miles from Earth, the researchers report in this week's issue of the journal Nature.

The asteroid Baptistina and rubble associated with it are thought to be leftovers, the scientists said.

Some of the debris from the collision escaped the asteroid belt, tumbled toward the inner solar system and whacked Earth and our moon, along with probably Mars and Venus, said William Bottke of the Southwest Research Institute in Boulder, Colorado, one of the researchers.

DEADLY COLLISION

The collision is believed to have doubled for a while the number of impacts occurring in this part of the solar system.

In fact, while the bombardment of this region of the solar system due to this shower of debris peaked about 100 million years ago, the scientists said the tail end of the shower continues to this day. Bottke said many existing near-Earth asteroids can be traced back to this collision.

"Imagine breaking up a big, big boulder on top of a hill and all the fragments rolling down the hill. And somewhere at the bottom is a village called Earth," Bottke said in a telephone interview.

The dinosaur-destroying meteorite, thought to have measured 6 miles across, plunged into Mexico's Yucatan Peninsula and blasted out the Chicxulub (pronounced CHIK-shu-loob) crater measuring about 110 miles wide. The researchers looked at evidence on the composition of this meteorite and found it consistent with the stony Baptistina.

The researchers estimated that there also was about a 70 percent probability that the prominent Tycho crater on the Moon, formed 108 million years ago and measuring about 55 miles

across, also was carved out by a remnant of the earlier asteroid collision.

Philippe Claeys of Vrije Universiteit Brussel in Belgium, who was not involved in the research, said by e-mail the findings were "clear evidence that the solar system is a violent environment and that collisions taking place in the asteroid belt can have major repercussions for the evolution of life on Earth."

Bottke emphasized that point. "Dinosaurs were around for a very long time. So the likelihood is they would still be around if that event had never taken place," Bottke said.

"Was humanity inevitable? Or is humanity just something that happened to arise because of this sequence of events that took place at just the right time. It's hard to say."

Moving Beyond Kyoto

http://www.nytimes.com/2007/07/01/opinion/01gore.html

July 1, 2007
Op-Ed Contributor
Moving Beyond Kyoto
By AL GORE
Nashville

WE — the human species — have arrived at a moment of decision. It is unprecedented and even laughable for us to imagine that we could actually make a conscious choice as a species, but that is nevertheless the challenge that is before us.

Our home — Earth — is in danger. What is at risk of being destroyed is not the planet itself, but the conditions that have made it hospitable for human beings.

Without realizing the consequences of our actions, we have begun to put so much carbon dioxide into the thin shell of air surrounding our world that we have literally changed the heat balance between Earth and the Sun. If we don’t stop doing this pretty quickly, the average temperature will increase to levels humans have never known and put an end to the favorable climate balance on which our civilization depends.

In the last 150 years, in an accelerating frenzy, we have been removing increasing quantities of carbon from the ground — mainly in the form of coal and oil — and burning it in ways that dump 70 million tons of CO2 every 24 hours into the Earth’s atmosphere.

The concentrations of CO2 — having never risen above 300 parts per million for at least a million years — have been driven from 280 parts per million at the beginning of the coal boom to 383 parts per million this year.

As a direct result, many scientists are now warning that we are moving closer to several “tipping points” that could — within 10 years — make it impossible for us to avoid irretrievable damage to the planet’s habitability for human civilization.

Just in the last few months, new studies have shown that the north polar ice cap — which helps the planet cool itself — is melting nearly three times faster than the most pessimistic computer models predicted. Unless we take action, summer ice could be completely gone in as little as 35 years. Similarly, at the other end of the planet, near the South Pole, scientists have found new evidence of snow melting in West Antarctica across an area as large as California.

This is not a political issue. This is a moral issue, one that affects the survival of human civilization. It is not a question of left versus right; it is a question of right versus wrong. Put simply, it is wrong to destroy the habitability of our planet and ruin the prospects of every generation that follows ours.

On Sept. 21, 1987, President Ronald Reagan said, “In our obsession with antagonisms of the moment, we often forget how much unites all the members of humanity. Perhaps we need some outside, universal threat to recognize this common bond. I occasionally think how quickly our differences would vanish if we were facing an alien threat from outside this world.”

We — all of us — now face a universal threat. Though it is not from outside this world, it is nevertheless cosmic in scale.

Consider this tale of two planets. Earth and Venus are almost exactly the same size, and have almost exactly the same amount of carbon. The difference is that most of the carbon on Earth is in the ground — having been deposited there by various forms of life over the last 600 million years — and most of the carbon on Venus is in the atmosphere.

As a result, while the average temperature on Earth is a pleasant 59 degrees, the average temperature on Venus is 867 degrees. True, Venus is closer to the Sun than we are, but the fault is not in our star; Venus is three times hotter on average than Mercury, which is right next to the Sun. It’s the carbon dioxide.

This threat also requires us, in Reagan’s phrase, to unite in recognition of our common bond.

Next Saturday, on all seven continents, the Live Earth concert will ask for the attention of humankind to begin a three-year campaign to make everyone on our planet aware of how we can solve the climate crisis in time to avoid catastrophe. Individuals must be a part of the solution. In the words of Buckminster Fuller, “If the success or failure of this planet, and of human beings, depended on how I am and what I do, how would I be? What would I do?”

Live Earth will offer an answer to this question by asking everyone who attends or listens to the concerts to sign a personal pledge to take specific steps to combat climate change. (More details about the pledge are available at algore.com.)

But individual action will also have to shape and drive government action. Here Americans have a special responsibility. Throughout most of our short history, the United States and the American people have provided moral leadership for the world. Establishing the Bill of Rights, framing democracy in the Constitution, defeating fascism in World War II, toppling Communism and landing on the moon — all were the result of American leadership.

Once again, Americans must come together and direct our government to take on a global challenge. American leadership is a precondition for success.

To this end, we should demand that the United States join an international treaty within the next two years that cuts global warming pollution by 90 percent in developed countries and by more than half worldwide in time for the next generation to inherit a healthy Earth.

This treaty would mark a new effort. I am proud of my role during the Clinton administration in negotiating the Kyoto protocol. But I believe that the protocol has been so demonized in the United States that it probably cannot be ratified here — much in the way the Carter administration was prevented from winning ratification of an expanded strategic arms limitation treaty in 1979. Moreover, the negotiations will soon begin on a tougher climate treaty.

Therefore, just as President Reagan renamed and modified the SALT agreement (calling it Start), after belatedly recognizing the need for it, our next president must immediately focus on quickly concluding a new and even tougher climate change pact. We should aim to complete this global treaty by the end of 2009 — and not wait until 2012 as currently planned.

If by the beginning of 2009, the United States already has in place a domestic regime to reduce global warming pollution, I have no doubt that when we give industry a goal and the tools and flexibility to sharply reduce carbon emissions, we can complete and ratify a new treaty quickly. It is, after all, a planetary emergency.

A new treaty will still have differentiated commitments, of course; countries will be asked to meet different requirements based upon their historical share or contribution to the problem and their relative ability to carry the burden of change. This precedent is well established in international law, and there is no other way to do it.

There are some who will try to pervert this precedent and use xenophobia or nativist arguments to say that every country should be held to the same standard. But should countries with one-fifth our gross domestic product — countries that contributed almost nothing in the past to the creation of this crisis — really carry the same load as the United States? Are we so scared of this challenge that we cannot lead?

Our children have a right to hold us to a higher standard when their future — indeed, the future of all human civilization — is hanging in the balance. They deserve better than a government that censors the best scientific evidence and harasses honest scientists who try to warn us about looming catastrophe. They deserve better than politicians who sit on their hands and do nothing to confront the greatest challenge that humankind has ever faced — even as the danger bears down on us.

We should focus instead on the opportunities that are part of this challenge. Certainly, there will be new jobs and new profits as corporations move aggressively to capture the enormous economic opportunities offered by a clean energy future.

But there’s something even more precious to be gained if we do the right thing. The climate crisis offers us the chance to experience what few generations in history have had the privilege of experiencing: a generational mission; a compelling moral purpose; a shared cause; and the thrill of being forced by circumstances to put aside the pettiness and conflict of politics and to embrace a genuine moral and spiritual challenge.

Al Gore, vice president from 1993 to 2001, is the chairman of the Alliance for Climate Protection. He is the author, most recently, of “The Assault on Reason.”