According to NASA, an asteroid will be passing by the Earth this Friday.

The asteroid is not big in size and is estimated to be between 15 and 30 metres in size.

The asteroid, which goes by the name 2018 CB, will pass closely by the Earth at around 5.30 pm EST (4 am on Saturday in India).

The asteroid will be passing by the Earth at a distance of about 64,000 kilometres from the Earth -- less than one-fifth the distance of Earth to the Moon.

Experts estimate 2018 CB to be larger than the asteroid that entered the atmosphere over Chelyabinsk, Russia in 2013.&nbsp;

Such asteroids do not usually come this close to our planet.&nbsp;

2018 CB was discovered recently on February 4 at the NASA-funded Catalina Sky Survey (CSS) in Arizona. Another asteroid discovered the same day as 2018 CB passed by the Earth on Tuesday.&nbsp;

Such asteroids do not usually do not come this close to our planet

According to NASA, an asteroid will be passing by the Earth this Friday. The asteroid is not big in size and is estimated to be between 15 and 30 metres in size. The asteroid, which goes by the name 2018 CB, will pass closely by the Earth at around 5.30 pm EST (4 am on Saturday in India). The asteroid will be passing by the Earth at a distance of about 64,000 kilometres from the Earth -- less than one-fifth the distance of Earth to the Moon. Experts estimate 2018 CB to be larger than the asteroid that entered the atmosphere over Chelyabinsk, Russia in 2013. Such asteroids do not usually come this close to our planet. 2018 CB was discovered recently on February 4 at the NASA-funded Catalina Sky Survey (CSS) in Arizona. Another asteroid discovered the same day as 2018 CB passed by the Earth on Tuesday.

Asteroid 2018 CB to pass by Earth this Friday

On Monday, June 19, NASA held a media briefing to announce the completed catalogue of exoplanets from the Kepler Mission.

The catalogue lists 4,034 exoplanet discoveries, including 219 new finds. Ten of these new worlds are close in size to the Earth and reside within their star&rsquo;s habitable zone, a location that would permit liquid water on the surface of an Earth-like world.

These ten join roughly 40 other worlds found by Kepler as possible candidates for Earth&rsquo;s twin. But is the prospect of another Earth really the Kepler legacy?

Teeming with planets

While planets had been discovered around other stars since the early 1990s, the launch of the Kepler Space Telescope in 2009 resulted in them being found in droves. As the numbers increased from tens to thousands of exoplanets, astronomers were able to identify types of planets and speculate on their frequency through our Galaxy; Kepler had given us the ability to do statistics.

Our Solar System suggests there are just two flavours of the planet: Terrestrial worlds like the Earth with rocky surfaces and thin atmospheres, and gas giants like Jupiter, whose solid cores are buried beneath thousands of kilometres of enveloping gases.

This neat, bimodal picture is taken to pieces in the Kepler Mission catalogue.

The catalogue contents reveal gas giants that orbit their star closer than Mercury, other worlds so hot their surface must be molten magma and planets around binary stars like Luke Skywalker&rsquo;s fictional home world of Tatooine in the film franchise Star Wars.

But perhaps the most mysterious entries are the so-called super-Earths.

How super, really?

Over two-thirds of the planets in the Kepler Mission Catalogue have radii of between 1.1 and four Earths, placing them between Earth and Neptune in size. These super-Earths are the most common planet discovered, yet our own Solar System has no analogue to tell us what such worlds might be like.

Are they terrestrial planets with rocky surfaces or mini gas giants with crushing atmospheric pressures? As interest has mounted in the prospect of finding a habitable planet, a key question is whether any of these worlds have a solid surface.

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Our Solar System has only cold gas and ice giants and rocky terrestrial planets, but the Kepler Mission revealed many other planet types. (Others)
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At the media briefing, NASA revealed that the Kepler Mission catalogue had produced a clue. A recent journal paper had spotted a split in the distribution of super-Earth planet sizes.

While planets with radii of around 1.3 Earths and 2.4 Earths are equally common, planets with sizes between 1.5 and two Earth radii are much harder to find. The astronomers speculate that this is the division between giant rocky planets and gaseous mini-Neptunes.

Although this strong divide in the super-Earth population has not previously been observed, its location agrees with the small number of planets we have bulk density measurements for. These density values suggest that planets larger than about 1.6 Earth radii have thick, Neptune-like atmospheres.

But while the Kepler Space Telescope can give us both sizes and locations for exoplanets, it cannot tell us anything about their past or the present surface environment. We need theories to explain the different planet types identified within the catalogue.

Explaining super-Earths

One possibility for the split in the super-Earth population is that the rocky planets have had their atmospheres stripped by radiation pouring from a star. Alternatively, the rocky worlds may have formed later from the gas-rich planet-forming disc that dispersed before the planets could accrue a thick atmosphere.

We meet a similar problem for the 50 planets found within the habitable zone. Knowing only their size and location is not enough to determine if their surfaces are similar to the Earth.

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The Kepler Mission data helped reveal a split in the super-Earth planet population, separating large rocky planets from small gas giants (B. J. Fulton). (Others)
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A difference in geology could create a very different atmosphere to our own, or the inability to create protective magnetic fields to shield the planet from sterilising stellar flares. The temperature may even be perfect for liquid water, but the planet entirely dry.

Without being able to probe surfaces, the Kepler telescope was never designed to find a true Earth twin. Rather, the mission catalogue tells us that planets can form around nearly every star and exist in a huge variety of conditions.

The Kepler Mission spanned four years (2009 to 2013), exploring a patch of sky in the Cygnus constellation. In May 2013, the second of the telescope&rsquo;s four gyroscope-like reaction wheels failed and it was unable to keep a stable position.

But the telescope continues to search the sky near the ecliptic plane (where the zodiac constellations lie), using radiation pressure from the Sun for positioning. This has become the K2 mission and has already found over 500 planets.

Future missions such as TESS and JWST (planned launch in 2018) and Ariel (planned launch in 2026) will add to this number, and begin to probe the environment of these worlds.

The Kepler Mission catalogue told us where to look, now we can begin to uncover what alien worlds are truly like.

This article was originally published on <a href="http://theconversation.com" rel="nofollow">The Conversation</a>. Read the <a href="https://theconversation.com/kepler-mission-has-released-its-catalogue-of-exoplanets-but-what-have-we-learnt-about-these-worlds-79817" rel="nofollow">original article</a>.

(Disclaimer: The opinions expressed above are the personal views of the author and do not reflect the views of ZMCL)

NASA's Kepler Mission has identified thousands of exoplanets but leaves a lot of questions about alien worlds.

On Monday, June 19, NASA held a media briefing to announce the completed catalogue of exoplanets from the Kepler Mission. The catalogue lists 4,034 exoplanet discoveries, including 219 new finds. Ten of these new worlds are close in size to the Earth and reside within their star’s habitable zone, a location that would permit liquid water on the surface of an Earth-like world. These ten join roughly 40 other worlds found by Kepler as possible candidates for Earth’s twin. But is the prospect of another Earth really the Kepler legacy? Teeming with planets While planets had been discovered around other stars since the early 1990s, the launch of the Kepler Space Telescope in 2009 resulted in them being found in droves. As the numbers increased from tens to thousands of exoplanets, astronomers were able to identify types of planets and speculate on their frequency through our Galaxy; Kepler had given us the ability to do statistics. Our Solar System suggests there are just two flavours of the planet: Terrestrial worlds like the Earth with rocky surfaces and thin atmospheres, and gas giants like Jupiter, whose solid cores are buried beneath thousands of kilometres of enveloping gases. This neat, bimodal picture is taken to pieces in the Kepler Mission catalogue. The catalogue contents reveal gas giants that orbit their star closer than Mercury, other worlds so hot their surface must be molten magma and planets around binary stars like Luke Skywalker’s fictional home world of Tatooine in the film franchise Star Wars. But perhaps the most mysterious entries are the so-called super-Earths. How super, really? Over two-thirds of the planets in the Kepler Mission Catalogue have radii of between 1.1 and four Earths, placing them between Earth and Neptune in size. These super-Earths are the most common planet discovered, yet our own Solar System has no analogue to tell us what such worlds might be like. Are they terrestrial planets with rocky surfaces or mini gas giants with crushing atmospheric pressures? As interest has mounted in the prospect of finding a habitable planet, a key question is whether any of these worlds have a solid surface. Our Solar System has only cold gas and ice giants and rocky terrestrial planets, but the Kepler Mission revealed many other planet types. (Others) × At the media briefing, NASA revealed that the Kepler Mission catalogue had produced a clue. A recent journal paper had spotted a split in the distribution of super-Earth planet sizes. While planets with radii of around 1.3 Earths and 2.4 Earths are equally common, planets with sizes between 1.5 and two Earth radii are much harder to find. The astronomers speculate that this is the division between giant rocky planets and gaseous mini-Neptunes. Although this strong divide in the super-Earth population has not previously been observed, its location agrees with the small number of planets we have bulk density measurements for. These density values suggest that planets larger than about 1.6 Earth radii have thick, Neptune-like atmospheres. But while the Kepler Space Telescope can give us both sizes and locations for exoplanets, it cannot tell us anything about their past or the present surface environment. We need theories to explain the different planet types identified within the catalogue. Explaining super-Earths One possibility for the split in the super-Earth population is that the rocky planets have had their atmospheres stripped by radiation pouring from a star. Alternatively, the rocky worlds may have formed later from the gas-rich planet-forming disc that dispersed before the planets could accrue a thick atmosphere. We meet a similar problem for the 50 planets found within the habitable zone. Knowing only their size and location is not enough to determine if their surfaces are similar to the Earth. The Kepler Mission data helped reveal a split in the super-Earth planet population, separating large rocky planets from small gas giants (B. J. Fulton). (Others) × A difference in geology could create a very different atmosphere to our own, or the inability to create protective magnetic fields to shield the planet from sterilising stellar flares. The temperature may even be perfect for liquid water, but the planet entirely dry. Without being able to probe surfaces, the Kepler telescope was never designed to find a true Earth twin. Rather, the mission catalogue tells us that planets can form around nearly every star and exist in a huge variety of conditions. The Kepler Mission spanned four years (2009 to 2013), exploring a patch of sky in the Cygnus constellation. In May 2013, the second of the telescope’s four gyroscope-like reaction wheels failed and it was unable to keep a stable position. But the telescope continues to search the sky near the ecliptic plane (where the zodiac constellations lie), using radiation pressure from the Sun for positioning. This has become the K2 mission and has already found over 500 planets. Future missions such as TESS and JWST (planned launch in 2018) and Ariel (planned launch in 2026) will add to this number, and begin to probe the environment of these worlds. The Kepler Mission catalogue told us where to look, now we can begin to uncover what alien worlds are truly like. This article was originally published on The Conversation. Read the original article. (Disclaimer: The opinions expressed above are the personal views of the author and do not reflect the views of ZMCL)

Opinion: What are NASA's exo-planets

British theoretical physicist Stephen Hawking, on his Chinese microblog Weibo account, praised the lead singer of China&#39;s most popular boy band for asking about life beyond Earth.

Wang Junkai, leader singer of the wildly popular TFBOYS, posted a video of himself on his Weibo account on Friday asking the author of &quot;A Brief History of Time&quot; how humanity should prepare for interstellar migration in years to come.

Hawking recently warned that the human race must evacuate Earth in 600 years before soaring energy consumption turns the planet into a &quot;ball of fire&quot;.

Earlier this month, Hawking made a video appearance at a science summit organised by Tencent Holdings and pleaded for investors to support his idea of travelling to the closest star outside our solar system in the hope of finding an inhabitable planet.

The 75-year old physicist said in a video posting on his Weibo account that Wang asked &quot;an excellent question&quot;, which gave him insight into Chinese millennnials and their &quot;curiosities&quot; regarding the future.

Wang and his two other band mates each have more than 30 million followers on their Twitter-like Weibo microblog accounts.

Owned by Weibo Corp, Weibo is China&#39;s biggest social media platform with more than 200 million active users.

Hawking, who opened his Weibo account last year, has 4.3 million followers, while British Prime Minister Theresa May has more than 900,000, having inherited her account from David Cameron.

Wang Junkai asked Hawking how humanity should prepare for interstellar migration in years to come

British theoretical physicist Stephen Hawking, on his Chinese microblog Weibo account, praised the lead singer of China's most popular boy band for asking about life beyond Earth. Wang Junkai, leader singer of the wildly popular TFBOYS, posted a video of himself on his Weibo account on Friday asking the author of "A Brief History of Time" how humanity should prepare for interstellar migration in years to come. Hawking recently warned that the human race must evacuate Earth in 600 years before soaring energy consumption turns the planet into a "ball of fire". Earlier this month, Hawking made a video appearance at a science summit organised by Tencent Holdings and pleaded for investors to support his idea of travelling to the closest star outside our solar system in the hope of finding an inhabitable planet. The 75-year old physicist said in a video posting on his Weibo account that Wang asked "an excellent question", which gave him insight into Chinese millennnials and their "curiosities" regarding the future. Wang and his two other band mates each have more than 30 million followers on their Twitter-like Weibo microblog accounts. Owned by Weibo Corp, Weibo is China's biggest social media platform with more than 200 million active users. Hawking, who opened his Weibo account last year, has 4.3 million followers, while British Prime Minister Theresa May has more than 900,000, having inherited her account from David Cameron.

Stephen Hawking lauds Chinese pop star for space migration question

The carbon dioxide emissions that drive global warming, flat since 2014, are set to rise two percent this year, dashing hopes they had peaked, scientists reported at UN climate talks Monday.

&quot;This is very disappointing,&quot; said Corinne Le Quere, director of the Tyndall Centre for Climate Change Research at the University of East Anglia and lead author of a major study detailing the findings.&nbsp;

&quot;With global CO2 emissions from human activities estimated at 41 billion tonnes for 2017, time is running out on our ability to keep warming below two degrees Celsius (3.6 degrees Fahrenheit), let alone 1.5 C.&quot;

The 196-nation Paris Agreement, adopted in 2015, calls for capping global warming at 2 C below pre-industrial levels.

With the planet out of kilter after only one degree of warming -- enough to amplify deadly heatwaves, droughts, and superstorms -- the treaty also vows to explore the feasibility of holding the line at 1.5 C.

Earth is overheating due to the burning of oil, gas and especially coal to power the global economy. Deforestation also plays a critical role.

&quot;The news that emissions are rising after a three-year hiatus is a giant leap backward for humankind,&quot; said Amy Luers, a climate policy advisor to Barack Obama and executive director of Future Earth, which co-sponsored the research.

This year&#39;s climate summit is presided by Fiji, one of the dozens of small island nations whose very existence is threatened by rising seas engorged by warmer water and melt-off from ice sheets on Greenland and Antarctica.

Thousands of diplomats in Bonn are negotiating the &quot;rulebook&quot; for the Paris pact, which goes into effect in 2020.

To stay below the 2 C threshold, greenhouse gas emissions should peak and begin to curve downward by 2020, earlier research has shown.

Stalled CO2 emissions from 2014 through 2016 -- due to better energy efficiency, a boom in renewables, and reduced coal use in China -- raised expectations that the world had turned the corner.

Those hopes were premature.&nbsp;&nbsp;

&quot;As each year ticks by, the chances of avoiding 2 C of warming continue to diminish,&quot; said co-author Glen Peters, research director at Center for International Climate Research in Oslo, Norway.

&quot;Given that 2 C is extremely unlikely based on current progress, then 1.5 C is a distant dream,&quot; he told AFP.

The study fingered China as the single largest cause of resurgent fossil fuel emissions in 2017, with the country&#39;s coal, oil and natural gas use up three, five and 12 percent, respectively.

Earth outside the safe zone&nbsp;

China alone accounts for nearly 30 percent of global carbon pollution.

Emissions from India -- the world&#39;s fourth largest emitter after the United States and the European Union -- are projected to grow by two percent, down from a 6.7-percent increase the year before.

2017 CO2 emissions in the United States will drop by only 0.4 percent, compared to 1.2 percent annually over the previous decade.

For the first time in five years, US coal use is projected to rise.&nbsp;

&quot;Human-induced warming has accelerated over the past few years despite the slowdown in carbon dioxide emissions because of other drivers of climate change, notably methane,&quot; said Myles Allen, a professor at the University of Oxford, commenting on the findings.

The Paris Agreement rests on voluntary carbon-cutting pledges from virtually every country in the world.

But even if fulfilled, those promissory notes are not enough to keep Earth in the safe zone, and would still see global temperatures rise a devastating 3 C (5.6 F) by the end of the century.

&quot;Global commitments made in Paris to reduce emissions are still not being matched by actions,&quot; said Peters.

The bottom line, say experts, is that the global economy is not shifting quickly enough from fossil fuels to low- or zero-carbon energy.&nbsp;

Solar and wind energy have grown 14 percent annually since 2012, but still only account for a tiny fraction -- less than four percent -- of global energy consumption.

The transition from dirty to clean energy has been slowed by oil, gas and coal subsidies that topped $320 million dollars (270 million euros) in 2015, according to the International Energy Agency.

Oceans and forests combined absorbed over half of the CO2 emissions from human activity, with the rest staying in the atmosphere, the study showed.&nbsp;

&quot;We would expect that the carbon sinks will eventually weaken as temperatures continue to rise, but how much and how fast is an active area of research,&quot; said Peters.

The International Union for Conservation of Nature (IUCN), meanwhile, released a report Monday showing that climate change now imperils one in four natural World Heritage sites, including coral reefs, glaciers, and wetlands -- nearly double the number from just three years ago.

Thousands of diplomats in Bonn are negotiating the "rulebook" for the Paris pact, which goes into effect in 2020

The carbon dioxide emissions that drive global warming, flat since 2014, are set to rise two percent this year, dashing hopes they had peaked, scientists reported at UN climate talks Monday. "This is very disappointing," said Corinne Le Quere, director of the Tyndall Centre for Climate Change Research at the University of East Anglia and lead author of a major study detailing the findings. "With global CO2 emissions from human activities estimated at 41 billion tonnes for 2017, time is running out on our ability to keep warming below two degrees Celsius (3.6 degrees Fahrenheit), let alone 1.5 C." The 196-nation Paris Agreement, adopted in 2015, calls for capping global warming at 2 C below pre-industrial levels. With the planet out of kilter after only one degree of warming -- enough to amplify deadly heatwaves, droughts, and superstorms -- the treaty also vows to explore the feasibility of holding the line at 1.5 C. Earth is overheating due to the burning of oil, gas and especially coal to power the global economy. Deforestation also plays a critical role. "The news that emissions are rising after a three-year hiatus is a giant leap backward for humankind," said Amy Luers, a climate policy advisor to Barack Obama and executive director of Future Earth, which co-sponsored the research. This year's climate summit is presided by Fiji, one of the dozens of small island nations whose very existence is threatened by rising seas engorged by warmer water and melt-off from ice sheets on Greenland and Antarctica. Thousands of diplomats in Bonn are negotiating the "rulebook" for the Paris pact, which goes into effect in 2020. To stay below the 2 C threshold, greenhouse gas emissions should peak and begin to curve downward by 2020, earlier research has shown. Stalled CO2 emissions from 2014 through 2016 -- due to better energy efficiency, a boom in renewables, and reduced coal use in China -- raised expectations that the world had turned the corner. Those hopes were premature. "As each year ticks by, the chances of avoiding 2 C of warming continue to diminish," said co-author Glen Peters, research director at Center for International Climate Research in Oslo, Norway. "Given that 2 C is extremely unlikely based on current progress, then 1.5 C is a distant dream," he told AFP. The study fingered China as the single largest cause of resurgent fossil fuel emissions in 2017, with the country's coal, oil and natural gas use up three, five and 12 percent, respectively. Earth outside the safe zone China alone accounts for nearly 30 percent of global carbon pollution. Emissions from India -- the world's fourth largest emitter after the United States and the European Union -- are projected to grow by two percent, down from a 6.7-percent increase the year before. 2017 CO2 emissions in the United States will drop by only 0.4 percent, compared to 1.2 percent annually over the previous decade. For the first time in five years, US coal use is projected to rise. "Human-induced warming has accelerated over the past few years despite the slowdown in carbon dioxide emissions because of other drivers of climate change, notably methane," said Myles Allen, a professor at the University of Oxford, commenting on the findings. The Paris Agreement rests on voluntary carbon-cutting pledges from virtually every country in the world. But even if fulfilled, those promissory notes are not enough to keep Earth in the safe zone, and would still see global temperatures rise a devastating 3 C (5.6 F) by the end of the century. "Global commitments made in Paris to reduce emissions are still not being matched by actions," said Peters. The bottom line, say experts, is that the global economy is not shifting quickly enough from fossil fuels to low- or zero-carbon energy. Solar and wind energy have grown 14 percent annually since 2012, but still only account for a tiny fraction -- less than four percent -- of global energy consumption. The transition from dirty to clean energy has been slowed by oil, gas and coal subsidies that topped $320 million dollars (270 million euros) in 2015, according to the International Energy Agency. Oceans and forests combined absorbed over half of the CO2 emissions from human activity, with the rest staying in the atmosphere, the study showed. "We would expect that the carbon sinks will eventually weaken as temperatures continue to rise, but how much and how fast is an active area of research," said Peters. The International Union for Conservation of Nature (IUCN), meanwhile, released a report Monday showing that climate change now imperils one in four natural World Heritage sites, including coral reefs, glaciers, and wetlands -- nearly double the number from just three years ago.

Global 2 per cent rise in CO2 'giant leap backwards for humankind'

The US space agency&#39;s Cassini spacecraft will end its 13-year mission to Saturn in mid-September by transmitting data until the final moment before it plunges into the ringed planet&#39;s atmosphere, officials said on Tuesday.

Cassini, the first spacecraft to orbit Saturn, will make the last of 22 farewell dives between the planet&#39;s rings and surface on Sept. 15. The spacecraft will then burn up as it heads straight into the gas giant&#39;s crushing atmosphere.

Cassini&#39;s final dive will end a mission that provided groundbreaking discoveries that included seasonal changes on Saturn, the moon Titan&#39;s resemblance to a primordial Earth, and a global ocean on the moon Enceladus with ice plumes spouting from its surface.

&quot;The mission has been insanely, wildly, beautifully successful, and it&#39;s coming to an end in about two weeks,&quot; Curt Niebur, Cassini program scientist, said on a telephone conference call with reporters from NASA&#39;s Jet Propulsion Laboratory in California.

Cassini&#39;s final photo as it heads into Saturn&#39;s atmosphere will likely be of propellers, or gaps in the rings caused by moonlets, said project scientist Linda Spilker.

The spacecraft will provide near real-time data on the atmosphere until it loses contact with Earth at 4:54 am&nbsp;PDT (1154 GMT) on Sept. 15, the National Aeronautics and Space Administration said.

Spilker said Cassini&#39;s latest data on the rings had shown they had a lighter mass than forecast. That suggests they are younger than expected, at about 120 million years, and thus were created after the birth of the solar system, she said.

During its final orbits between the atmosphere and the rings, Cassini also studied Saturn&#39;s atmosphere and took measurements to determine the size of the planet&#39;s rocky core.

Cassini has been probing Saturn, the sixth planet from the sun, and its entourage of 62 known moons since July 2004. It has provided enough data for almost 4,000 scientific papers.

Since the craft is running low on fuel, NASA is crashing it into Saturn to avoid any chance Cassini could someday collide with Titan, Enceladus or any other moon that has the potential to support indigenous microbial life.

By destroying the spacecraft, NASA will ensure that any hitchhiking Earth microbes still alive on Cassini will not contaminate the moons for future study.

Cassini, the first spacecraft to orbit Saturn, will make the last of 22 farewell dives between the planet's rings and surface on Sept. 15.

The US space agency's Cassini spacecraft will end its 13-year mission to Saturn in mid-September by transmitting data until the final moment before it plunges into the ringed planet's atmosphere, officials said on Tuesday. Cassini, the first spacecraft to orbit Saturn, will make the last of 22 farewell dives between the planet's rings and surface on Sept. 15. The spacecraft will then burn up as it heads straight into the gas giant's crushing atmosphere. Cassini's final dive will end a mission that provided groundbreaking discoveries that included seasonal changes on Saturn, the moon Titan's resemblance to a primordial Earth, and a global ocean on the moon Enceladus with ice plumes spouting from its surface. "The mission has been insanely, wildly, beautifully successful, and it's coming to an end in about two weeks," Curt Niebur, Cassini program scientist, said on a telephone conference call with reporters from NASA's Jet Propulsion Laboratory in California. Cassini's final photo as it heads into Saturn's atmosphere will likely be of propellers, or gaps in the rings caused by moonlets, said project scientist Linda Spilker. The spacecraft will provide near real-time data on the atmosphere until it loses contact with Earth at 4:54 am PDT (1154 GMT) on Sept. 15, the National Aeronautics and Space Administration said. Spilker said Cassini's latest data on the rings had shown they had a lighter mass than forecast. That suggests they are younger than expected, at about 120 million years, and thus were created after the birth of the solar system, she said. During its final orbits between the atmosphere and the rings, Cassini also studied Saturn's atmosphere and took measurements to determine the size of the planet's rocky core. Cassini has been probing Saturn, the sixth planet from the sun, and its entourage of 62 known moons since July 2004. It has provided enough data for almost 4,000 scientific papers. Since the craft is running low on fuel, NASA is crashing it into Saturn to avoid any chance Cassini could someday collide with Titan, Enceladus or any other moon that has the potential to support indigenous microbial life. By destroying the spacecraft, NASA will ensure that any hitchhiking Earth microbes still alive on Cassini will not contaminate the moons for future study.

NASA to crash US spacecraft into Saturn, 13-year mission to complete soon

Our Earth may once have been a spinning, donut-shaped mass of hot, vapourised rock - called &quot;synestia&quot; - according to scientists who proposed the new type of planetary object.

Synestia is a spinning planetary object that forms as planet-sized objects smash into each other.

At one point early in its history, Earth was likely a synestia, said Sarah Stewart, scientist at the University of California Davis in the US.

Current theories of planet formation hold that rocky planets such as Earth, Mars and Venus formed early in the solar system when smaller objects smashed into each other. These collisions were so violent that the resulting bodies melted and partially vapourised, eventually cooling and solidifying to the nearly spherical planets we know today.

In the new study, researchers modeled what happens when the Earth-sized rocky planets collide with other large objects with high energy and momentum.

&quot;We looked at the statistics of giant impacts, and we found that they can form a completely new structure,&quot; Stewart said.

Researchers found that over a range of high temperatures and momenta, planet-sized bodies could form a new, much larger structure, an indented disk rather like a red blood cell or a donut with the center filled in. The object is mostly vaporised rock, with no solid or liquid surface.

They have dubbed the new object a &quot;synestia,&quot; from &quot;syn&quot; - meaning &quot;together&quot; - and &quot;Estia,&quot; the Greek goddess of architecture and structures.

The key to synestia formation is that some of the structure&#39;s material goes into orbit.

In a spinning, solid sphere, every point from the core to the surface is rotating at the same rate. However, in a giant impact, the material of the planet can become molten or gaseous and expands in volume.

If it gets big enough and is moving fast enough, parts of the object pass the velocity needed to keep a satellite in orbit, and that is when it forms a huge, disc-shaped synestia, according to the study. Most planets likely experience collisions that could form a synestia at some point during their formation, Stewart said.

For an object like Earth, the synestia would not last very long perhaps a hundred years before it lost enough heat to condense back into a solid object. However, synestia formed from larger or hotter objects such as gas giant planets or stars could potentially last much longer, she said.

The synestia structure also suggests new ways to think about lunar formation, researchers said.

The Moon is remarkably like Earth in composition, and most current theories about how the moon formed involve a giant impact that threw material into orbit. However, such an impact could have instead formed a synestia from which the Earth and Moon both condensed, Stewart said.

No one has yet observed a synestia directly, but they might be found in other solar systems once astronomers start looking for them alongside rocky planets and gas giants, she said.

(PTI)

Scientists say the Earth could have been formed from planetary objects colliding with each other

Our Earth may once have been a spinning, donut-shaped mass of hot, vapourised rock - called "synestia" - according to scientists who proposed the new type of planetary object. Synestia is a spinning planetary object that forms as planet-sized objects smash into each other. At one point early in its history, Earth was likely a synestia, said Sarah Stewart, scientist at the University of California Davis in the US. Current theories of planet formation hold that rocky planets such as Earth, Mars and Venus formed early in the solar system when smaller objects smashed into each other. These collisions were so violent that the resulting bodies melted and partially vapourised, eventually cooling and solidifying to the nearly spherical planets we know today. In the new study, researchers modeled what happens when the Earth-sized rocky planets collide with other large objects with high energy and momentum. "We looked at the statistics of giant impacts, and we found that they can form a completely new structure," Stewart said. Researchers found that over a range of high temperatures and momenta, planet-sized bodies could form a new, much larger structure, an indented disk rather like a red blood cell or a donut with the center filled in. The object is mostly vaporised rock, with no solid or liquid surface. They have dubbed the new object a "synestia," from "syn" - meaning "together" - and "Estia," the Greek goddess of architecture and structures. The key to synestia formation is that some of the structure's material goes into orbit. In a spinning, solid sphere, every point from the core to the surface is rotating at the same rate. However, in a giant impact, the material of the planet can become molten or gaseous and expands in volume. If it gets big enough and is moving fast enough, parts of the object pass the velocity needed to keep a satellite in orbit, and that is when it forms a huge, disc-shaped synestia, according to the study. Most planets likely experience collisions that could form a synestia at some point during their formation, Stewart said. For an object like Earth, the synestia would not last very long perhaps a hundred years before it lost enough heat to condense back into a solid object. However, synestia formed from larger or hotter objects such as gas giant planets or stars could potentially last much longer, she said. The synestia structure also suggests new ways to think about lunar formation, researchers said. The Moon is remarkably like Earth in composition, and most current theories about how the moon formed involve a giant impact that threw material into orbit. However, such an impact could have instead formed a synestia from which the Earth and Moon both condensed, Stewart said. No one has yet observed a synestia directly, but they might be found in other solar systems once astronomers start looking for them alongside rocky planets and gas giants, she said. (PTI)

Early Earth may have been donut-shaped: study

The world&#39;s biggest and most-valuable diamonds like the famed Kohinoor may have formed from metallic liquid deep inside the Earth&#39;s mantle, according to a new study.

Researchers from the Gemological Institute of America studied the unique properties of diamonds with similar characteristics to famous stones such as the Cullinan, Constellation and Kohinoor by examining their so-called &quot;offcuts,&quot; which are the pieces left over after the gem&#39;s facets are cut for maximum sparkle.

They determined that these diamonds sometimes have tiny metallic grains trapped inside them that are made up of a mixture of metallic iron and nickel, along with carbon, sulphur, methane and hydrogen.

These inclusions indicate that the diamonds formed, like all diamonds, in the Earth&#39;s mantle, but they did so under conditions in which they were saturated by liquid metal.

As unlikely as it sounds, their research shows that pure carbon crystallised from this pool of liquid metal in order to form the large gem diamonds.

&quot;The existence of this metal mixture has broad implications for our understanding of deep Earth processes,&quot; said Evan Smith from the Gemological Institute of America.

Diamonds form deep in the Earth&#39;s mantle and shoot to the surface in minor volcanic eruptions of magma.

Impurities contained inside diamonds can teach geologists about deep Earth chemistry under the pressure, temperature, and chemical conditions in which they were formed.

Diamonds, once formed, have a unique ability to protect and shield any minerals contained inside their crystal structures, thereby giving scientists a special, protected sample of the mantle mineralogy and a glimpse at conditions miles beneath the planet&#39;s surface.

Most diamonds form at depths around 145 to 241 kilometres under the continents. However, the so-called &quot;superdeep&quot; diamonds form much deeper - at depths below 386 kilometres, where the mantle rocks are known to be mobile due to convection.

From the team&#39;s work, we now understand for the first time that large gem diamonds are a group of superdeep diamonds, according to analysis of tiny samples of silicate that were also found inside the studied diamonds.

These tiny silicate inclusions are also associated with the metal. These tiny samples of metal, along with their associated methane and hydrogen, tells researchers about oxygen availability in different parts of the mantle.

Near the surface, the mantle chemistry is more oxidised, which scientists can tell from the presence of carbon in the form of carbon dioxide in magmas erupted in volcanoes.

However, deeper down, according to the researchers, some regions of the mantle are the opposite of oxidised, or reduced, which is what allows the iron-nickel liquid metal to form there.

The study was published in the journal Science.

(PTI)

Their research shows that pure carbon crystallised from this pool of liquid metal in order to form the large gem diamonds

The world's biggest and most-valuable diamonds like the famed Kohinoor may have formed from metallic liquid deep inside the Earth's mantle, according to a new study. Researchers from the Gemological Institute of America studied the unique properties of diamonds with similar characteristics to famous stones such as the Cullinan, Constellation and Kohinoor by examining their so-called "offcuts," which are the pieces left over after the gem's facets are cut for maximum sparkle. They determined that these diamonds sometimes have tiny metallic grains trapped inside them that are made up of a mixture of metallic iron and nickel, along with carbon, sulphur, methane and hydrogen. These inclusions indicate that the diamonds formed, like all diamonds, in the Earth's mantle, but they did so under conditions in which they were saturated by liquid metal. As unlikely as it sounds, their research shows that pure carbon crystallised from this pool of liquid metal in order to form the large gem diamonds. "The existence of this metal mixture has broad implications for our understanding of deep Earth processes," said Evan Smith from the Gemological Institute of America. Diamonds form deep in the Earth's mantle and shoot to the surface in minor volcanic eruptions of magma. Impurities contained inside diamonds can teach geologists about deep Earth chemistry under the pressure, temperature, and chemical conditions in which they were formed. Diamonds, once formed, have a unique ability to protect and shield any minerals contained inside their crystal structures, thereby giving scientists a special, protected sample of the mantle mineralogy and a glimpse at conditions miles beneath the planet's surface. Most diamonds form at depths around 145 to 241 kilometres under the continents. However, the so-called "superdeep" diamonds form much deeper - at depths below 386 kilometres, where the mantle rocks are known to be mobile due to convection. From the team's work, we now understand for the first time that large gem diamonds are a group of superdeep diamonds, according to analysis of tiny samples of silicate that were also found inside the studied diamonds. These tiny silicate inclusions are also associated with the metal. These tiny samples of metal, along with their associated methane and hydrogen, tells researchers about oxygen availability in different parts of the mantle. Near the surface, the mantle chemistry is more oxidised, which scientists can tell from the presence of carbon in the form of carbon dioxide in magmas erupted in volcanoes. However, deeper down, according to the researchers, some regions of the mantle are the opposite of oxidised, or reduced, which is what allows the iron-nickel liquid metal to form there. The study was published in the journal Science. (PTI)

'Biggest, best diamonds formed deep inside Earth's mantle'

Aliens may take another 1,500 years to contact us as Earth&#39;s physical attributes are not unique, making it difficult for the extraterrestrials to locate us, a new study has found. 
 
&quot;We haven&#39;t heard from aliens yet, as space is a big place, but that doesn&#39;t mean no one is out there,&quot; said Evan Solomonides, from the Cornell University in the US. 
 
&quot;It&#39;s possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now,&quot; said Solomonides.&nbsp;&quot;Until then, it is possible that we appear to be alone - even if we are not. But if we stop listening or looking, we may miss the signals. So we should keep looking,&quot; he said. 
 
Astronomers from Cornell University deconstructed the Fermi Paradox and paired it with the Mediocrity Principle into a fresh equation.&nbsp;According to the Fermi Paradox, billions of Earth-like planets exist in our galaxy, yet no aliens have contacted or visited us. Thus the paradox: the cosmos teems with possibility. 
 
The mediocrity principle - proposed by 16th-century mathematician Copernicus - states that the Earth&#39;s physical attributes are not unique, as natural processes are likely common throughout the cosmos, and therefore aliens would not discover us for a while. 
 
Hunting for extraterrestrials means sending out signals like television broadcasts, for example. As Earth&#39;s electronic ambassador, TV and radio signals are sent into space as a byproduct of broadcasting. 
 
These signals have been travelling from Earth for 80 years at the speed of light. 
 
For aliens receiving these transmissions, they would likely be indecipherable, said Solomonides, as the extraterrestrials would need to decode light waves into sounds, then parse 3,000 human languages to grasp the message. 
 
Earth&#39;s broadcast signals have reached every star within about 80 light years from the Sun - about 8,531 stars and 3,555 Earth-like planets, as our Milky Way galaxy alone contains 200 billion stars, researchers said. 
 
Combining the equations for the Fermi Paradox and the mediocrity principle, the researchers suggest that the Earth might hear from an alien civilisation when about half of the Milky Way Galaxy has been signalled in about 1,500 years. 
(PTI)

'We haven't heard from aliens yet, as space is a big place, but that doesn't mean no one is out there'

Aliens may take another 1,500 years to contact us as Earth's physical attributes are not unique, making it difficult for the extraterrestrials to locate us, a new study has found. "We haven't heard from aliens yet, as space is a big place, but that doesn't mean no one is out there," said Evan Solomonides, from the Cornell University in the US. "It's possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now," said Solomonides. "Until then, it is possible that we appear to be alone - even if we are not. But if we stop listening or looking, we may miss the signals. So we should keep looking," he said. Astronomers from Cornell University deconstructed the Fermi Paradox and paired it with the Mediocrity Principle into a fresh equation. According to the Fermi Paradox, billions of Earth-like planets exist in our galaxy, yet no aliens have contacted or visited us. Thus the paradox: the cosmos teems with possibility. The mediocrity principle - proposed by 16th-century mathematician Copernicus - states that the Earth's physical attributes are not unique, as natural processes are likely common throughout the cosmos, and therefore aliens would not discover us for a while. Hunting for extraterrestrials means sending out signals like television broadcasts, for example. As Earth's electronic ambassador, TV and radio signals are sent into space as a byproduct of broadcasting. These signals have been travelling from Earth for 80 years at the speed of light. For aliens receiving these transmissions, they would likely be indecipherable, said Solomonides, as the extraterrestrials would need to decode light waves into sounds, then parse 3,000 human languages to grasp the message. Earth's broadcast signals have reached every star within about 80 light years from the Sun - about 8,531 stars and 3,555 Earth-like planets, as our Milky Way galaxy alone contains 200 billion stars, researchers said. Combining the equations for the Fermi Paradox and the mediocrity principle, the researchers suggest that the Earth might hear from an alien civilisation when about half of the Milky Way Galaxy has been signalled in about 1,500 years. (PTI)

Aliens may take 1,500 more years to contact Earth: Study

The new planet is in constellation Lyra and is likely to be rocky and possibly could have oceans, scientists said.

A planet which about 1,200 light-years away from Earth and 40 per cent larger than its size may be habitable, according to US researchers.

Kepler-62f, which is in the direction of the constellation Lyra, is within the range of planets that are likely to be rocky and possibly could have oceans, scientists said. 
 
NASA&#39;s Kepler mission discovered the planetary system that includes Kepler-62f in 2013, and it identified Kepler-62f as the outermost of five planets orbiting a star that is smaller and cooler than the sun, they said.

But the mission did not produce information about Kepler-62f&#39;s composition or atmosphere or the shape of its orbit.

Now, scientists from University of California Los Angeles (UCLA) and University of Washington came up with possible scenarios about what its atmosphere might be like and what the shape of its orbit might be to determine whether the planet could sustain life.

&quot;We found there are multiple atmospheric compositions that allow it to be warm enough to have surface liquid water.

This makes it a strong candidate for a habitable planet,&quot; said Aomawa Shields from UCLA.

On Earth, carbon dioxide makes up 0.04 percent of the atmosphere, researchers said.

Because Kepler-62f is much farther away from its star than Earth is from the sun, it would need to have dramatically more carbon dioxide to be warm enough to maintain liquid water on its surface, and to keep from freezing, they said.

Researchers ran computer simulations based on Kepler-62f having an atmosphere that ranges in thickness from the same as Earth&#39;s all the way up to 12 times thicker than our planet&#39;s.

Kepler-62f also has various concentrations of carbon dioxide in its atmosphere, ranging from the same amount as is in the Earth&#39;s atmosphere up to 2,500 times that level, and there are several different possible configurations for its orbital path, scientists said.

They found many scenarios that allow it to be habitable, assuming different amounts of carbon dioxide in its atmosphere.

Shields said that for the planet to be consistently habitable throughout its entire year, it would require an atmosphere that is three to five times thicker than Earth s and composed entirely of carbon dioxide.

Having such a high concentration of carbon dioxide would be possible for the planet because, given how far it is from its star, the gas could build up in the planet&#39;s atmosphere as temperatures get colder to keep the planet warm, she said.

Scientists made their calculations of the shape of the planet&#39;s possible orbital path using an existing computer model called HNBody, and they used existing global climate models to simulate its climate.

The findings were published in the journal Astrobiology.

Researchers have found a new planet 1,200 light-years from earth that might have life.

The new planet is in constellation Lyra and is likely to be rocky and possibly could have oceans, scientists said. A planet which about 1,200 light-years away from Earth and 40 per cent larger than its size may be habitable, according to US researchers. Kepler-62f, which is in the direction of the constellation Lyra, is within the range of planets that are likely to be rocky and possibly could have oceans, scientists said. NASA's Kepler mission discovered the planetary system that includes Kepler-62f in 2013, and it identified Kepler-62f as the outermost of five planets orbiting a star that is smaller and cooler than the sun, they said. But the mission did not produce information about Kepler-62f's composition or atmosphere or the shape of its orbit. Now, scientists from University of California Los Angeles (UCLA) and University of Washington came up with possible scenarios about what its atmosphere might be like and what the shape of its orbit might be to determine whether the planet could sustain life. "We found there are multiple atmospheric compositions that allow it to be warm enough to have surface liquid water. This makes it a strong candidate for a habitable planet," said Aomawa Shields from UCLA. On Earth, carbon dioxide makes up 0.04 percent of the atmosphere, researchers said. Because Kepler-62f is much farther away from its star than Earth is from the sun, it would need to have dramatically more carbon dioxide to be warm enough to maintain liquid water on its surface, and to keep from freezing, they said. Researchers ran computer simulations based on Kepler-62f having an atmosphere that ranges in thickness from the same as Earth's all the way up to 12 times thicker than our planet's. Kepler-62f also has various concentrations of carbon dioxide in its atmosphere, ranging from the same amount as is in the Earth's atmosphere up to 2,500 times that level, and there are several different possible configurations for its orbital path, scientists said. They found many scenarios that allow it to be habitable, assuming different amounts of carbon dioxide in its atmosphere. Shields said that for the planet to be consistently habitable throughout its entire year, it would require an atmosphere that is three to five times thicker than Earth s and composed entirely of carbon dioxide. Having such a high concentration of carbon dioxide would be possible for the planet because, given how far it is from its star, the gas could build up in the planet's atmosphere as temperatures get colder to keep the planet warm, she said. Scientists made their calculations of the shape of the planet's possible orbital path using an existing computer model called HNBody, and they used existing global climate models to simulate its climate. The findings were published in the journal Astrobiology.

A planet that may sustain life found 1,200 light-years away from Earth

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