Mysteries of Space
Black holes, alien life, the Big Bang... space and its mysteries have always fascinated people and inspired artists and writers. We know quite a lot about space, but there is far more we don't know. So what is fact and what is fantasy?
Lives of the stars
Other mysteries, such as how stars are born in nebulae and die in supernovae are gradually being solved with the help of incredibly powerful telescopes. But there is a long way to go.
But do UFOs really exist?
Fact or fiction?
Curiosity about aliens has produced lots of ideas about what they might look like, In some books and films, aliens look much like humans with two arms and legs, while in others, they resemble giant blobs or spiders.
A novel about an alien invasion from Mars was published in 1958 named The war of the worlds by H.G. Wells.
Flying saucer shaped objects, crop circles, lights in the night sky... people have long claimed to see and find evidence of UFOs (Unidentified Flying Objects). Look at some of the claims yourself. What do you think?
A UFO comes into land? Is this trucks wing mirror or something more mysterious?
These are intricate designs made from flattened areas of corn. Some believe they are the landing sites of flying saucers, but many have been proved to have been manmade.
The idea that intelligent life exists outside our solar system has always seemed to intrigue people. This cave painting is thousands of years old. It appears to depict an extraterrestrial encounter.
Was it a strange craft?
The Apollo picture shown thoroughly investigated, and found to be nothing more mysterious than the floodlight boom, used when astronauts left the spacecraft.
In the news
Some newspapers have even reported the landing of alien spacecraft. The most famous of these incidents occurred at a place called Roswell, USA, when strange debris was found in 1947.
What was Roswell?
People claimed the debris found at Roswell was of a spacecraft that crashed. Early newspaper reports called it a "flying disc". However, the military said it was a top secret weather balloon.
An alien spacecraft?
Roswell resulted in a number of books, films, stories, and general speculation. However, most people now believe that it was a weather balloon in 1955 caughted in Roswell.
Do you know?
There is a road sign in Roswell, USA, the scene of space ships investigations in the 1940s.
The most incidents reported about UFO in USA
In the Bible, Ezekiel seems to describe the appearance of a UFO at least, some people think so. He told of a fiery, wheeled object in the sky that shot lightning bolts.
Is anyone there?
If there are aliens, it is unlikely they will speak the languages of Earth, so communication may be a problem. Coded signals have been sent into space. People are also listening for signals from space.
The search for Extra Terrestrial Intelligence (SETI) uses powerful radio telescopes to scan for alien signals. However, so far nothing has been found.
Message into space
In 1974, astronomers at Arecibo, Puerto Rico, sent a radio message from us to the stars. It was sent towards a cluster of stars called M13, where it will arrive in 25,000 years. We may then get a reply after another 25,000 years (if anybody is there to read it!).
The Arecibo message lasts three minutes. It consists of 1,679 pulses, which when arranged form a pictogram. The pictogram explains the basis of life.
The message includes
Numbers from one to ten
Atoms including carbon and hydrogen
Some interesting molecules
Spiral structure of DNA
A human from and Earth's population
Earth's position in our solar system
The telescope that sent the message
A plaque into space
The spaceprobes Pioneer 10 and 11 carry engraved metal plaques. It is a space equivalent of a message in a bottle! The plaques reveal Earth's place in the solar system, the probes route away from Earth, and give the outlines of a man and woman.
A record into space
The Voyager spacecraft, sent up in 1979 and 1981, each carried a gold-plated LP record, a disc that has encoded sounds and photographs that will provide an alien intelligence with an idea of life on Earth. There are greetings in 56 languages and that includes a recording of whale song,
Do you know?
Earth have almost 7000 language and no one knows how many languages speak in the universe.
Is there life on Mars?
Historically, many people have believed that a race of creatures live on Mars. Representations have appeared in books, artwork, comics, on the radio, and on television and in films in many different forms. Do any of these creatures actually exist? No!
Two hundred years ago
In the 1780s, William Herschel observed seasonal changes around the Martian poles and noted that its inhabitants "probably enjoy a situation in many respects similar to our own".
In the papers
In the 1920s, a newspaper report on the Martians claimed they would have very large noses and ears and immense lung development... Their legs are poorly developed, because matter on Mars weighs less than here.
One hundred years ago
The idea of intelligent Martian life reached a peak at the turn of the twentieth century, when a wealthy businessman, Percival Lowell (1855-1916), set up his own observatory in Arizona, USA, and began to study Mars.
A big prize!
In 1901, the French Guzman prize offered an award of 100,000 francs for the first person to make contact with extraterrestrials. Terms actually excluded contact with Martians as it was believed to be too easy!
Camille Flammarion's founder of the Sociate Astronomique) "Flat Earth" woodcut influenced Pierre Guzman who offered the prize,
Martians sell books
We now know the lines weren't there, but many people believed Lowell's theories, caught up by the excitement of the idea. The discussions inspired H.G.Wells' The War of the Worlds, a book published in 1898.
Lowell claimed he could see a network of lines criss-crossing the surface of Mars, which he believed were built to transport water from the poles around the planet.
In 1938, a radio dramatization of HG Wells' book by Orson Welles sent a million Americans into panic The broadcast described the Martian invasion of Earth in the form of a news report.
Percival Lowell mapped and claimed that he sees 160 canals.
The Big Bang
The Big Bang: "a day without yesterday"
Most scientists now believe that the Universe was born from a hot, dense spot more than 13 billion years ago. They call this event the Big Bang.
As the Universe expands and cools, at 300,000 years, matter as we know it starts to form. The Universe is a thousandth of its size today
A Universe is born
What was later termed the Big Bang was first proposed by Georges Lemaitre in 1931. Scientists believe it was the beginning of everything, but don't know what caused it to happen.
Space and time were brought to life from a minute speck, which was unbelievably hot and heavy, The energy contained in this speck immediately began to spread out, in the form of an ever expanding fireball.
A long time coming
Matter only began to form bundreds of thousands of years after the Big Bang, long after the fireball had cooled. The resulting gases would form the stars, planets, and galaxies that exist today,
Stars and galaxies start to form after about 300 million years
At 9 billion years the Universe looks much as it does today, if a little bit smaller. Our Sun starts to form.
Scientists have detected a faint radio signal, present in any direction they look for it in space. They believe it is a faint glow from the Big Bang's superhot fireball. It is called The Cosmic Background Radiation.
The Cosmic Background Radiation was discovered by American physicists Arno Penzias and Robert Wilson in the 1960s.
No beginning, no end
An alternative to the Big Bang, the Steady State Theory claimed there was no beginning or end for the Universe. It's just always been there. Few scientists now believe in the Steady State Theory.
Do you know?
The astronomer who gave the Big Bang theory its name didn't support it. He termed it Big Bang as a criticism and was surprised that the name stuck. He believed in the Steady State Theory.
We think Big Bang is not an explosion
Black holes are a great mystery. Astronomers know they are there, because of their effect on nearby stars (if a star is too close, it gets pulled towards the hole), but they have proved very difficult to study. Why? Because they are black, and that makes them invisible!
Scientists believe a black hole may be formed by the death of a star. This picture shows a star's explosion as it dies.
Sometimes some of the falling gas Is squirted back out as hot jets
This artist's idea of a black hole, shows clouds of gas and dust swirling rapidly around it before being pulled in towards the hole at the centre.
Why are they there?
Black holes are sometimes born when a star explodes and dies. When a big star has run out of fuel it can't stop gravity pulling its gas together, squeezing it tighter and tighter until it forms a tiny neutron star, or a black hole.
Into the hole
Black holes have such strong gravity that nothing in the surrounding space can escape, not even light. However, they do not act as enormous vacuum cleaners something has to get close enough to be in danger of being pulled in. They are a bit like space whirlpools, affecting just their area of space.
How do we find the holes?
Scientists can find black holes because gas and dust falling into a hole rubs together and becomes incredibly hot. This gives off x-rays which space telescopes detect.
Astronauts into black holes
The black hole's gravity would pull harder on the astronaut's feet than at their head.
The astronaut would be stretched into a long, thin, spaghetti-like shape, finally being crushed to an invisible speck.
If an astronaut entered a black hole, at first he or she wouldn't notice.
This X-ray picture shows a black hole (the blue dot) at the centre of a galaxy with a mass 30 million times that of our Sun. The orange dots are just black holes eating stars that got too close
Is that true?
Some people think a black hole may be a doorway to another universe. But it's all just speculation. Nobody really knows. However, it is doubtful someone could survive the journey through the hole to find out. An astronaut unfortunate enough to try would be stretched out like a piece of spaghetti.
A black hole is big because they grow as they eat, so they are only limited in size by the matter they consume.
Are there other Earths?
Astronomers know that there are planets outside our solar system. One day they hope to discover a planet that is capable of supporting life. The search has begun.
Exoplanet HD 1897336 was discovered in 2005 as it dimmed the light of its parent stor when possing in front of it
Other space telescopes that are looking for planets include Europe's COROT satellite. It has already detected a planet.
We know only Earth is the only planet have actual life.
A recent discovery
Twenty light years away from us lies a star called Gliese 581. Astronomers have identified three planets orbiting Gliese. One is too hot for life, one is too cold, but one is in the Goldilocks zone and it may be just right.
Gliese 581 is a red dwarf star
Gliese 581c takes 13 days to orbit its sun, and may be the right distance from it to support life. Gliese 581c may be rocky or it may be composed of gas. Nobody is really sure. Gliese 581c is thought to be about 19,300 km (12,000 miles) across, with a mass five times that of Earth.
Gliese 581b takes 5.4 days to orbit its sun and is too hot to support life.
Gliese 581d takes 84 days to orbit its sun and is too cold to support life
Gliese 581c is thought to orbit in the Goldilocks, or "habitable zone", where the surface temperatures would allow liquid water.
Compared to Earth
The planets we find are so distant that it is difficult to be sure of their size, or their composition.
Are there others?
Exoplanets, or solar planets, are planets orbiting a star other than our Sun. More than 200 exoplanets have been identified since the first was discovered in 1995. Astronomers believe there are many more. Exoplanets cannot be seen through a telescope. One way they are found is by looking for a star's "wobble" as it is affected by an orbiting planet.
A star is born
Clusters of stars are constantly being born from clouds of dust and gas thousands of times the size of our solar system in a process that can take millions of years.
Born in a cloud
Between existing stars, there are patches of dust and gas. Gradually, these draw in more and more dust and gas to form huge clouds called nebulae. Clumps of matter gather together in these clouds.
As this matter gets more and more dense, heat builds up to form a young star that fills the surrounding nebulae with light and colour.
We have fusion!
With enough matter, this process continues. The star gets denser and hotter. Eventually nuclear fusion begins, releasing huge amounts of heat and light, a star is born.
Is that one red?
Some stars shine red, others shine yellow or bluish white. A star's colour depends on its temperature. Red stars are the coolest, while blue stars are the hottest.
In the same way lava reveals its temperature through its colour. The yellow lava is hotter than the red
Our Sun is a yellow dwarf star
What's in a name?
Horsehead, Lagoon, Eagle and Cat's Eye... some of the best known nebulae have popular names inspired by their shape.
What type of star?
Stars have different characteristics according to the amount of matter involved in their birth. They differ in colour, temperature, and brightness, and in the length of time they stay alive.
The life of a star
The Universe is home to lots of different types of star,
Red dwarfs are smaller than our Sun. They burn fuel slowly, so they live a long time.
Young solar systems Leftover material from a star's formation can turn into planets.
Blue giants are among the hottest stars, and live for less than 100 million years.
Supergiants are the rarest stars, They have short lives under 50 million years.
Do you know?
The Pleiades star is known as seven sisters because seven of its stars without a telescope.
Death of a star
Stars are born, live out their lives, and, ultimately, die. In dying, all their elements are thrown back into the clouds of gas and dust from which they formed, and the process begins again.
When a star such as our Sun gets old, it begins to expand. It becomes a red giant or supergiant. This is because as it uses up its fuel, hydrogen, its centre or core becomes smaller and hotter. That leads to its expansion.
The surface of a planet whose sky is filled with a red giant star.
Do you know?
We are made from elements such as oxygen, hydrogen, carbon, and iron. Hydrogen has been around since time began, while the other elements get made inside stars and spread when they die.
Sun continue to burn its hydrogen for next five billion years to finish its burning fuel.
Once it's hot enough, a red giant starts to burn a new fuel called helium. That pushes the outer layers of the star further out. The star then begins to lose these layers as a nebula, and eventually emerges as a small, white dwarf star.
Going out with a bang
Some giant stars end their lives with a huge explosion called a supernova. Sometimes the centre will survive as a black hole or neutron star.
A lighthouse in space
Some neutron stars send out radio waves that sweep around as the star spins. Astronomers can pick up these signals. These neutron stars are called pulsars.