Tuesday, February 03, 2009

Space



What may be the smallest extrasolar planet, measuring less than twice the size of Earth, has been discovered orbiting a sun-like star.

The world is far hotter than ours, however. And controversy over the size claim has heated up, too.

Astronomers used the COROT space telescope (a mission led by the French Space Agency, and also involving the European Space Agency and others) to detect the new planet as it transited its parent star, dimming the light from the star as it passed in front of it.

The host star is located 457 light-years from Earth, where one light-year is the distance light will travel in a year, or about 6 trillion miles (10 trillion kilometers).

"For the first time, we have unambiguously detected a planet that is 'rocky' in the same sense as our own Earth," said Malcolm Fridlund, ESA's COROT Project Scientist. "We now have to understand this object further to put it into context, and continue our search for smaller, more Earth-like objects with COROT."

He added, "This discovery is a very important step on the road to understanding the formation and evolution of our planet."

Sara Seager, an astrophysicist at MIT who was not involved in the discovery said, "My first thought is that it's extremely exciting because we've been waiting to find a planet that we can really call rocky. I would just caution that more information, more data, is needed."

For instance, the discovery has yet to be published in a peer-reviewed journal, and not much information about the planet has been released by COROT scientists.

Seager says in order to confirm an exoplanet is rocky, scientists need to nail down its mass and radius (or the combination of size and density, or mass and density).

"It looks like the mass is not well-determined and so that's why they're saying they're not sure what the density is," Seager told SPACE.com. "They think it is terrestrial-like. It might have water ice, or it might have rocks, but it's certainly not a gas giant."

COROT scientists estimate the planet ranges from 5.7 to 11 Earth masses.

Hot discovery

One big difference in the newfound planet compared to Earth: COROT-Exo-7b is located very close to its star, orbiting once every 20 hours.

Its temperature is so high, ranging from 1,832 to 2,732 degrees Fahrenheit (1,000 to 1,500 degrees Celsius) that the researchers say the exoplanet could be covered in lava or water vapor.

The density of the planet is still under investigation, though scientists say it may be rocky like Earth and covered in liquid lava.

COROT-Exo-7b may also belong to a class of planets that are thought to be made up of water and rock in almost equal amounts. Given the high temperatures measured, the planet would likely be a very hot and humid place.

"Finding such a small planet was not a complete surprise," said Daniel Rouan, researcher at the Observatoire de Paris Lesia, who coordinates the project with Alain Leger, from Institut d'Astrophysique Spatiale. "COROT-Exo-7b belongs to a class of objects whose existence had been predicted for some time."

Small and odd

Very few of the more than 300 exoplanets found so far have a mass comparable to that of Earth and the other terrestrial planets — Venus, Mars and Mercury. That's because terrestrial planets are extremely difficult to detect.

Of the Earth-like planets detected, this is the first one spotted using the so-called transit method, which can yield both the planet's mass and radius. Other methods just reveal the planet's mass, Seager said.

The newfound planet's size status is also questioned. When astronomers study planets, they're interested in both mass and diameter.

"The claim that it is the 'smallest exoplanet' found to date is not correct," said planet-formation theorist Alan Boss of the Carnegie Institution of Washington. "It is the smallest mass exoplanet found to date that transits, but other hot super-Earths have been found that do not transit but have lower masses."

Boss was not involved in the current discovery.

For instance, he adds Gliese 876 d has "a minimum mass of 5.9 Earth masses and a best estimate for the true mass of 7.5 Earth masses."

Most of the methods used so far are indirect and sensitive to the mass of the planet, which is why bigger worlds are easier to detect.

COROT can directly measure the size of a planet's surface, which is an advantage to astronomers. In addition, because the probe is in space, it has longer periods of uninterrupted observation than from the ground.

The internal structure of COROT-Exo-7b particularly puzzles scientists, as they are unsure whether it is an "ocean planet," a kind of planet whose existence has never been proved so far.

In theory, such planets would initially be covered partially in ice, and they would later drift toward their star, with the ice melting to cover it in liquid.

http://www.foxnews.com/story/0,2933,487485,00.html

Not exactly a vacation destination, unless you are looking to get that crispy beach tan in a fraction of a second. :)

It is still interesting how, as the techniques are refined, smaller and smaller planets are being found. Makes the search for truly Earth-like planets less science-fiction and more science-possible.

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Pure mathematics is, in its way, the poetry of logical ideas.

Albert Einstein

The first article posted said European Space Agency. Posting this news here, and a moderator can remove it. I searched for a thread, really.

'Silver sensation' seeks cold cosmos

Monday, 9 February 2009

The Herschel space observatory is ready for its great voyage

Stare into the curve of Herschel's mirror too long and you get a slightly giddy feeling that comes from not being able to judge where its surface really starts.

It is enchanting, spectacular and - at 3.5m in diameter - it will soon become the biggest telescope mirror in space, surpassing that of Hubble.

The great 18th Century astronomer William Herschel would have been astonished by the silver sensation that now bears his name.
The design keeps Herschel's critical detectors in an ultra-cold state


More details


The European Space Agency (Esa) is certainly very proud of its new observatory. It has been working on the venture for more than 20 years.

"The mirror is an enormous piece of hardware," enthused Thomas Passvogel, Esa's programme manager on the Herschel space observatory.

"It's a ceramic mirror; it's the biggest piece ever made from silicon carbide. It's very hard but much, much lighter than glass and the performance is excellent."

This week, the finished observatory will be flown to Europe's Kourou spaceport in South America. There, it will be bolted to an Ariane rocket and hurled into orbit.

It will take up a vantage point a million-and-a-half kilometres from Earth, to open up what scientists expect to be an utterly fascinating new vista on the Universe.

"Very simply, the science pillars of Herschel are to understand better how stars and galaxies form and how they evolve," Göran Pilbratt, Esa's project scientist on Herschel, told BBC News.

There is also a u-tube video within the link.

http://news.bbc.co.uk/2/hi/science/nature/7864087.stm

Here is a link to the BBC article:
Herschel
Tullio

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Galaxy has 'billions of Earths'

There could be one hundred billion Earth-like planets in our galaxy, a US conference has heard.

Dr Alan Boss of the Carnegie Institution of Science said many of these worlds could be inhabited by simple lifeforms.

He was speaking at the annual meeting of the American Association for the Advancement of Science in Chicago.

So far, telescopes have been able to detect just over 300 planets outside our Solar System.

Very few of these would be capable of supporting life, however. Most are gas giants like our Jupiter; and many orbit so close to their parent stars that any microbes would have to survive roasting temperatures.

But, based on the limited numbers of planets found so far, Dr Boss has estimated that each Sun-like star has on average one "Earth-like" planet.

This simple calculation means there would be huge numbers capable of supporting life.

"Not only are they probably habitable but they probably are also going to be inhabited," Dr Boss told BBC News. "But I think that most likely the nearby 'Earths' are going to be inhabited with things which are perhaps more common to what Earth was like three or four billion years ago." That means bacterial lifeforms.

Dr Boss estimates that Nasa's Kepler mission, due for launch in March, should begin finding some of these Earth-like planets within the next few years.

Recent work at Edinburgh University tried to quantify how many intelligent civilisations might be out there. The research suggested there could be thousands of them.

http://news.bbc.co.uk/2/hi/science/nature/7891132.stm

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