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                Trails in the Sky

Read the text and try to understand it completely,then answer the questions.

Sometimes when we look at the sky we can see a white trail being traced in it. Many people believe it’s a Unidentified Flying Object, or a UFO. From time to time it happens in the sky some strange phenomenon. We can see lights  apparently coming from nowhere or, as in this case, two white trails of vapor. Some lights are not so easy to explain, what makes people believe more and more in flying saucers. We are not saying whether they exist or not,we are just making a remark about the fact. There are some “facts” or perhaps “legends" about UFOs sightings. In the USA there ‘s a place called area 51 ,where, according to a lot of people and newspapers, in the 50’s a flying saucer crashed and was captured by the Army. It  seems there were four aliens inside it, one of them alive. Many people say there is a conspiracy to keep the secret of the super advanced technology learned from that UFO. What remains a fact is that in the 60’s the USA had a jet plane called "Blackbird” that was able to fly at Mach 3 (that’s 3 times the sound speed, about 3600 Km per hour) at an altitude of 22,000 meters. That plane was used as a spy plane, but after satellites began to work the plane wasn't useful any more and was retired. Perhaps someone who saw that plane flying so  fast, had thought it was from another planet. UFOs aside, what remains is that “there are more mysteries between heaven and earth than dreams our philosophy (adapted from Shakespeare).(Leia a pagina--UFO)

 Anyway, the picture above shows something much more real. It’s a Jumbo Jet Plane flying 33,000 feet high (Veja a pagina Medidas) and the white trails are produced by the heat of  jet engines in the surrounding air that is about 50 degrees Celsius negative. If you are inside the plane it is  difficult to see the trails. They start about 15 meters back from the engines and it takes a few seconds to become visible. Remember that a Jumbo can fly at 900 Km per hour. Now imagine you are about 70 years old and you lived all your life away from cities in the country. One day you see something very strange in the air: two white trails growing from horizon to horizon. What would you think that thing was? A UFO? The end of the world? The wrath of God? The signal of  good news? Just a different kind of cloud?
It  depends completely on your beliefs, your knowledge about natural phenomena , your mind acceptance of something new, and many other things. So if you see something strange, stop , think, analyze and don’t believe in legends but try to see the truth, in the sky or in your daily life. The principle is the same.

Responda as questões de acordo com o texto
Basta responder "YES"  ou "NO"
1- All lights in the sky are easy to explain,aren't they? 
2- From time to time it happens a strange phenomenon,doesn't it? 


3- The author says UFOs exist, right? 


4- Blackbird was a slow plane, wasn't it?


5- The white trails are produced by the air, right?


6- The air is very cold at 33,000 feet high,isn't it?


7- A Jumbo Plane can fly very fast,can't it?


8- It is always easy to see the trails if you´re inside the plane, isn't it?


9- The plane in the photo is above the clouds, isn't it?


10- The Blackbird was a plane from the sixties,wasn't it?



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