Why are distant galaxies moving away faster?
The universe is thought to be around 14 billion years old. When it was first created, the explosion blasted everything out into space. This means that all of the galaxies, including our own Milky Way galaxy is moving at incredible speeds. When planetary scientists first started having the ability to take a look at the farthest galaxies near the end of the universe, they appeared to be moving faster than our own. Could that be true? Could these galaxies actually be moving faster?
In the 1920’s, an astronomer named Edwin Hubble made the discovery that the farther galaxies seemed to be moving away faster. Hubble measured the amount of light that was coming from the distant galaxies, and, calculated the amount of ‘redshift’ in the color. As light moves farther away it loses all of the most powerful colors (the blues) and shifts towards the end of the color spectrum, which is red. This discovery included that the farther away a galaxy was, the faster it was moving away. This was called the ‘Hubble Constant’ and since then, scientists have been trying to figure out exactly why this is happening.
One of the first things that the planetary scientists had to find out was the actual speed of many of the galaxies. The Hubble Space Telescope, which now orbits earth, was named about Edwin Hubble, and thanks to the images from that telescope they have been able to study some of the galaxy speeds. They located some special types of stars called Cepheids that gave them a kind of ‘marker’ to figure out the speed. Without the Hubble Telescope, this might have taken years to decipher.
Scientists located these Cepheid stars and when they did the math, they started to find out that the galaxies were actually expanding slower in the past than they are now. This means that the more time that passes, the faster that galaxies are expanding. They continued to examine the speeds using the light of a supernova and this seemed to confirm their observations.
None of the results of the studies made any sense, because according to the laws of physics, an object should maintain the same original speed, unless something blocks it or an energy force is added to increase the speed. Scientists began to develop a theory that there might be some mysterious unknown force, like anti-gravity, that is actually pushing the galaxies apart. If this is true, it would explain why the galaxies at the furthest end of the universe (the ones that are the oldest) are moving faster and faster away from us.
It is thought that at this rate, the universe will continue to expand eternally and not collapse, as was once thought, into a final ‘Big Crunch’. As newer satellite telescopes are launched into space, planetary scientists will have the chance to learn even more about the expanding galaxies. The next generation of high tech telescopes will be the James Webb Space Telescope and it will be able to see deeper into space than the Hubble Telescope.
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