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Are we alone in the Universe?
Transcript of Are we alone in the Universe?
in the Universe? Extraterrestrial life How life began? The Habitable Zone Exoplanets in the HZ 4 billion years ago... Curiosity on Mars Curiosity Mt. Sharp When we speak about extra solar planets, it’s important to explain the Habitable Zone concept.
The Habitable Zone is the distance from a star to allow for liquid water. The planet has to be at the right distance from the star to allow for liquid water, and this distance depends of the brightness of the star. Gale crater Curiosity's landing area Kepler space telescope 17 billion of like-Earth planets... 500 million in the HZ Beyond our Solar System When we speak about extra-terrestrial life, normally people thinks in ET, green men, UFO, aliens invading our planet and other things like these...
But, this is not real.
Presently, there is no scientific evidence for extra-terrestrial life. The first question is how life began. Our knowledge is limited to the Earth, and when we're talking about life we mean life as we know it: carbon based organic life forms that need liquid water to exist.
We know that life began in the seas 4 billion years ago. So, logically, if we were able to find liquid water on other planets, we could expect to find life in them.
This is the way scientist have taken in the last years. However, we are making great efforts and investing resources to know if is possible to find life out of the Earth and what kind of life. The first stop we are going to do is on Mars.
This is the NASA’s rover Curiosity in a self-portrait.
Today he is working on Mars surface and he is giving us fantastic landscapes from Mars.
But the main target of Curiosity’s mission is to find life or evidences of life on Mars. Curiosity mission The rover is studying whether the landing region at Gale crater had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed on Mars surface. The portion of the crater where Curiosity has landed has an alluvial fan likely formed by water-carried sediments. Scientist are trying to drive the rover to the base of Mt. Sharp. The layers at the base of the mountain contain clays and sulphates, both known to form in water. Mars is a perfect place for searching evidences of life because we know that there was water flowing in the past, so Mars could also have had life on it. In fact, while life was beginning on Earth, Mars was covered by oceans, lakes and flowing liquid water on its surface, so if life began on Earth, why not on Mars with the same conditions? But, what happen if we search life out of our Solar System?
Is possible to find other stars with planets orbiting around them? In 1995 this two astronomers announced that they had discovered a planet, 51 Pegasi B, in orbit around the star 51 Pegasi. The first exoplanet found orbiting a star. It’s a giant planet, with Jupiter’s size, orbiting very close to its star. Too hot for hosting life.
But the most important of all was that we finally had the ability to detect planets orbiting other stars. Since then, we have discovered a total of 854 planets orbiting other stars. In the beginning, the majority of them where giant planets, but scientists are improving day after day their technology and now we can detect planets slightly larger than the Earth. This is thanks, specially, to the Kepler space telescope. Was launched in 2009 and its mission is to discover Earth-like planets orbiting other stars. In our Solar System, Venus is out of the inner edge of the HZ (too hot) and Mars is close to the outer edge of the HZ (in the limit). So the most interesting thing for us is to detect Earth–like planets orbiting its stars within the HZ. Kepler Mission has discovered several exoplanets in the HZ.
The Kepler spacecraft has identified a further 54 candidates (green band) from a total of 2740 planets. From this, there are only 9 slightly larger than the Earth potential exoplanets in the HZ. Few planets? 9 seems a small number of planets, but we have to consider that all these discoveries have occurred in our neighbourhood.
We have studied a little area in our galaxy of 300 light years from our sun.
Imagine what we could find in the rest of the galaxy.
In fact, latest estimates from NASA talks about 17 billion Earth-like planets in the Milky Way, 500 million of which could be in the habitable zone. And if this is not enough, imagine in the rest of the Universe, with about 100 to 200 billion of galaxies... Unfortunately, they are so far away, it is unlikely that we will ever know if life exists within them.