Bibliografia consultada:
http://pt.wikipedia.org/wiki/Castelo_de_Vinhais
http://www.cm-vinhais.pt/municipio/historia.html
http://www.lifecooler.com/Portugal/patrimonio/CastelodeVinhaisvestigios
Pictures from Trás-os-Montes region, Douro region, Bragança, Portugal and others beautiful places
It has long been known that some asteroids cross Earth's orbit, coming significantly close and potentially entering a collision course with our planet. These asteroids are under constant surveillance and monitoring. Earth has a history of violent impacts, and some collisions were capable of causing the extinction of a large percentage of living species, such as the collision 65 million years ago that created the Chicxulub crater in Mexico's Yucatán province. Other smaller collisions have left marks across various parts of the Earth's surface.
In 2004, an asteroid named Apophis (99942 Apophis) was discovered, which has a 1 in 250,000 probability (NASA laboratory calculations) [1] of colliding with planet Earth in the year 2036, with this asteroid rated at level 1 on the Torino scale (up to 10). This 140-meter-long asteroid will make a close approach to planet Earth in 2029 and could collide with it in 2036 if its orbit is modified by the gravitational pull exerted by Earth. According to some scientists, the impact of this asteroid would cause massive, large-scale damage. NASA estimates the impact energy at 880 megatons of TNT, 114,000 times the energy released by the Hiroshima atomic bomb (www.wikipedia.org). This celestial body has become one of the most closely watched objects by astronomers. Although presenting a reduced threat in 2036, this asteroid will make another close approach to our planet in 2068, where the odds of collision increase slightly. Recent news reports published across various newspapers and websites mention another potentially dangerous asteroid that could collide with Earth in 2182. The asteroid, named 1999 RQ36, has a 1 in 1,000 chance of colliding with Earth [2].
Although we are dealing with probabilities, the danger exists, and it would be important to join forces in developing technological solutions capable of preventing these types of collisions. And as the saying goes, better safe than sorry, lest the sky fall on our heads one day.
A ponte romana de Chaves, também designada por ponte de Trajano, foi construída sobre o rio Tâmega entre finais do século I e inícios do século II d.C. Esta ponte tem cerca de 150 metros de comprimento e uma dúzia de arcos."What a wonderful and stupendous scheme we have here of the magnificent vastness of the universe! So many suns, so many Earths […] (1).
Since 1995, the year the first extrasolar planet orbiting a Sun-like star was discovered by M. Mayor and D. Queloz, more than 400 exoplanets have already been found (403 planets as of October 19, 2009) (2). The first planets to be discovered were gas giants, mostly with masses hundreds of times greater than Earth's, some describing strangely elongated orbits, and others so close to their respective stars that they orbit them in just a few days or even hours (3).
New detection instruments available to astronomers have recently made it possible to discover smaller planets as well as provide data on their composition and geology. In April 2007, the most Earth-like planet (Gliese 581c) was discovered. With an estimated temperature between 0 and 40ºC, it could have liquid water on its surface (4). In September 2009, the planet CoRoT-7b was discovered. This planet is five times more massive than Earth. It has a rocky surface and a density similar to our planet; however, it is far too hot because it is very close to its sun (5).
Sagan and Shklovsky (6) supported the idea that there would be billions of planetary systems in our galaxy alone, and that around 1 billion of those worlds would be populated with their own varieties of living organisms. Astronomers are convinced they will soon discover small, Earth-like planets where some form of life could develop. We await new discoveries."