quinta-feira, 26 de abril de 2007

Descoberto o primeiro planeta parecido com a Terra

Chamaram-lhe Gliese 581C

Não, esta ainda é a nossa...

Na realidade é algo optimista, ainda, dizer que o planeta é parecido com a Terra. É um planeta com uma massa que é 1,5 vezes a da Terra, em órbita de uma estrela gigante vermelha - Gliese 581, na constelação da Balança, a 21 anos-luz da Terra - a uma distância que lhe permite beneficiar de temperaturas parecidas com as da Terra, ou seja, em que pode existir água no estado líquido, logo, vida.

Evidentemente que daí a dizer que o planeta é parecido com a Terra vai uma grande distância. Ainda não se pode analisar a atmosfera do planeta, não se sabe se há água ou oxigénio ou o que quer se seja acerca daquele planeta.

No entanto é uma descoberta histórica, porque é o primeiro planeta que é descoberto com o tipo de condições que lhe permitirão ser um candidato a 'irmão da Terra'.

Fonte: Adelaide Now

Link: Universe Today

New earth find suggests we are not alone
April 26, 2007 02:15am

ASTRONOMERS have found a "new Earth" - the first planet outside our solar system with the potential for life as we know it.

The Earth-like planet is 20.5 light years away, orbiting the "red dwarf" star Gliese 581 in the constellation Libra.

It is one of three planets in that solar system, with the Earth-like planet named Gliese 581C.

Commenting on the discovery by a team of European scientists, University of Adelaide Professor Roger Clay said this was the first time a planet with a mass or weight similar to the Earth's had been found.

"They believe that its distance from the star would mean the surface temperature is not that different to the surface temperature of Earth," he said.

This meant water would be in a liquid form.

"So, potentially, it is the sort of place that you'd start looking to find some sort of life form... it does seem to have the right ingredients."

The discovery, at the European Southern Observatory's telescope in La Silla, Chile, was made using spectroscopy.

The technique is based on the principle that light is shifted more towards the blue end of the spectrum when something is moving towards you and more towards red when it is moving away, Professor Clay said.

It worked in this case because the planet has a tight orbit and the star was relatively lightweight, so movement was easier to detect. The discovery appears to confirm suspicions of astronomers that the universe has many Earth-like worlds.

The new planet is about 1 1/2 times the diameter of the Earth. It is the first exoplanet (a planet orbiting a star other than our own Sun) that is like our Earth. Of the 220 or so exoplanets found to date, most have either been too big, made of gas rather than solid material, far too hot, or far too cold for life to survive. "On the treasure map of the universe, one would be tempted to mark this planet with an X," said Xavier Delfosse, one of the scientists who discovered the planet.

"Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extraterrestrial life."

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