Learn about the how the Hubble space telescope detects light in space. Also learn about the variety of stars and the visibility of their light and distance.
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Learn About the Hubble's Starlight Detection This is the big bang and this is how many scientists believed our universe began. Since the Hubble space telescope was launched, one of its most important uses has been to serve as a time machine allowing astronomers to look back to the beginnings of time. Light may travel through space at a speed faster than any or you can imagine but it is still a fine art speed. Light from very distant stars are therefore very old and because it is in space, Hubble can much better to take faint and distant light sources. This will show how things were when light began its journey billions of years ago. One of the key questions astronomers have wanted to answer for decades is how old and big our universe is. Hubble was built to answer these questions. Since the big bang when time began, the universe has been expanding. The weight of the expansion called the Hubble constant holds the key to determine the age and the size of the universe. By running the expansion back like a film until everything is compressed into that small point from which the universe submerged. Its age and size can be estimated. But how can you get images from a film that has been running for billions of years? To determine the age of the light sources Hubble sees, astronomers look for remote, accurate standard candles. A special class of variable stars called Cepheids. This table and predictable variations tell astronomers exactly how faraway they are. In this way, they serve as reliable comparisons for nearby Supernovae which are much brighter than the Cepheids and can be seen at far greater distances. Hubble has measured the light from Cepheids and ancient Supernova explosions with the highest accuracy so far. And today, we therefore know the age of the universe better than ever before, around 14 billion years. An astonishing discovery Hubble has made is at the expansion rate of our universe has changed with time. When astronomers observe the most distant Supernova they found that these stars are dimmer than they should be. This implies that they must be farther away than predicted. Most astronomers believe this is a signature that the universe is accelerating its expansion and galaxies are getting away from one another more and more rapidly. Hubble also gave us the most detailed view of what a universe actually look like when it was younger. Just as geologist dig deeper underground to find ancient fossils, so astronomers ventured deeper and deeper towards the beginning of time, looking for light coming from the faintest and most distant objects. In 1995, Hubble was pointed to the same place in the sky for 10 days in a row. The first so called deep field observation copied the technique of time lapse photographers who keep their camera shot open to capture faint details. The observation revealed thousands of previously unknown galaxies of various sizes, shapes and colors. Besides the classical spiral and atypical shaped galaxies, there is a variety of other galaxy shapes and colors that gave important clues to understanding the evolution of the universe. One of the most stunning results is the discovery that most stars formed a few billion years after the birth of the universe.
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