The great feature of an island is its geographical isolation .View from the sky, we see « cut off from the world. » Our maps or our terrestrial globe we show as a small dot in the blue ocean. For its inhabitants, this small point is equally fondamental.Important for people who dream to expand on its beaches.
Our land is extremely isolated in infinite cosmos.View from outside our solar system, we do not even see: more noticeable Saturn and Jupiter the Sun itself.The pictures taken from the moon we show all blue in space, away from all the other planets.
Vision touching this little blue planet carrier of life,is precious.De endearing and makes our days, we can easily go from one island to the other, even distant from one continent to another and vice versa.
Only a few people were able to travel (? … True or false!) In the space to the moon and back!
Interstellar travel is still imaginary, although short trips to the ISS have trivialized the information and that the « wonder » of my youth fades gradually! A mission to Mars would require some travel hundreds of millions of miles … It is not for tomorrow, the great adventure already so romanticized by Hollywood!
All the islands of the Earth are greatly threatened by the immediate consequences of global warming and the ultimate climat.It is insured this will provocate a rapid rise in sea level and all oceans.Menaced, they are irremediably because their altitude is low.The tourist beaches will be submerged, and places highly prized, will disapear forever in the eyes of the futur humanity .The inhabitants of some islands are already back on the farthest points or emigrate.
Continents of the world have their threatened coastline, each being a huge island … finally Similarly the Earth is a very small island, directly threatened by even the smallest of the big wave turbulence driven by the spatial motion of our galaxy: the Milky Way!
The Hubble space telescope has detected what scientists believe is the oldest galaxy ever seen before.
Thirteen billion years. That would be the age of the galaxy recently observed by Hubble. It already existed 480 million years after the Big Bang.
The new image, taken by Hubble and published in the journal Nature, was detected using a wide angle camera recently installed on the Hubble Space Telescope. The NASA scientists have observed a rapid growth of this galaxy in a very short time. They then think that there was a period when galaxy formation was intensively activated. About 500 million years after the Big Bang, there would have been a galaxy, while 150 million years later, a dozen others have emerged. The researchers even claim that this account has doubled from 100 million years.
First there were a few stars and clusters, baby galaxies, and finally the majestic galaxies we see today, according to Professor Richard Bouwens, interviewed by the BBC. He compares the galaxy discovered by Hubble in a newborn: it is much smaller than galaxies like our Milky Way, but it grows faster. « We can use these new measures to know how fast the galaxies are formed and grow, » explains Professor Bouwens. They will also get more details about the early days of the Universe at the time of the first stars and galaxies.
Robert Massey of the Royal Astronomical Society (RAS), believes the new image captured by the space telescope will also allow astronomers to adjust their theories about the evolution of the Universe. If this new Hubble observation is yet to be confirmed, scientists remain confident teams.
In all cases, astronomers are eagerly awaiting the launch of the James Webb Space Telescope at NASA in 2014. The resolution of these instruments will be used, inter alia, to observe the first stars and galaxies that formed after the Big Bang.
Astronomers have long known that many surveys of distant galaxies miss 90% of their targets, but they didn’t know why. Now, astronomers have determined that a large fraction of galaxies whose light took 10 billion years to reach us have gone undiscovered. This was found with an extremely deep survey using two of the four giant 8.2-meter telescopes that make up ESO’s Very Large Telescope (VLT) and a unique custom-built filter. The survey also helped uncover some of the faintest galaxies ever found at this early stage of the Universe.
Astronomers frequently use the strong, characteristic “fingerprint” of light emitted by hydrogen known as the Lyman-alpha line, to probe the amount of stars formed in the very distant Universe Yet there have long been suspicions that many distant galaxies go unnoticed in these surveys. A new VLT survey demonstrates for the first time that this is exactly what is happening. Most of the Lyman-alpha light is trapped within the galaxy that emits it, and 90% of galaxies do not show up in Lyman-alpha surveys.
“Astronomers always knew they were missing some fraction of the galaxies in Lyman-alpha surveys,” explains Matthew Hayes, the lead author of the paper, published this week in Nature, “but for the first time we now have a measurement. The number of missed galaxies is substantial.”
To figure out how much of the total luminosity was missed, Hayes and his team used the FORS camera at the VLT and a custom-built narrowband filter to measure this Lyman-alpha light, following the methodology of standard Lyman-alpha surveys. Then, using the new HAWK-I camera, attached to another VLT Unit Telescope, they surveyed the same area of space for light emitted at a different wavelength, also by glowing hydrogen, and known as the H-alpha line. They specifically looked at galaxies whose light has been traveling for 10 billion years (redshift 2.2), in a well-studied area of the sky, known as the GOODS-South field.
“This is the first time we have observed a patch of the sky so deeply in light coming from hydrogen at these two very specific wavelengths, and this proved crucial,” said team member Goran Ostlin. The survey was extremely deep, and uncovered some of the faintest galaxies known at this early epoch in the life of the Universe. The astronomers could thereby conclude that traditional surveys done using Lyman-alpha only see a tiny part of the total light that is produced, since most of the Lyman-alpha photons are destroyed by interaction with the interstellar clouds of gas and dust. This effect is dramatically more significant for Lyman-alpha than for H-alpha light. As a result, many galaxies, a proportion as high as 90%, go unseen by these surveys. “If there are ten galaxies seen, there could be a hundred there,” Hayes said.
Different observational methods, targeting the light emitted at different wavelengths, will always lead to a view of the Universe that is only partially complete. The results of this survey issue a stark warning for cosmologists, as the strong Lyman-alpha signature becomes increasingly relied upon in examining the very first galaxies to form in the history of the Universe. “Now that we know how much light we’ve been missing, we can start to create far more accurate representations of the cosmos, understanding better how quickly stars have formed at different times in the life of the Universe,” said co-author Miguel Mas-Hesse.
The breakthrough was made possible thanks to the unique camera used. HAWK-I, which saw first light in 2007, is a state-of-the-art instrument. “There are only a few other cameras with a wider field of view than HAWK-I, and they are on telescopes less than half the size of the VLT. So only VLT/HAWK-I, really, is capable of efficiently finding galaxies this faint at these distances,” said team member Daniel Schaerer.
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