We can peer back in time Looking out into space is like looking - TopicsExpress

We can peer back in time Looking out into space is like looking back in time. That is because light from objects that are far away takes longer to reach us than light from objects nearby. If an object is a million light years away, we are seeing it as it looked a million years ago. Modern telescopes are so powerful that they can view objects many billions of light years away, close to the time of the Big Bang. If the Big Bang did happen, then wed expect those distant views to reveal clouds of gas which have not yet turned into stars and galaxies. Astronomers have recently found gas clouds like this in the distant Universe. Some of them are around 12 or 13 billion years old. Even at this incredible distance, we can tell what they are made of by using a technique called spectroscopy to analyse light that passes through them. As Big Bang theory predicts, these ancient gas clouds are made of very different stuff to the modern Universe. Most of the chemical elements in the modern Universe are made inside stars. Because the gas clouds come from a time before stars, they consist almost entirely of the most basic elements, hydrogen and helium.