How can one make the iconic Hubble Ultra Deep Field image even better? How about adding some ultraviolet light to the image? Well, that's exactly what astronomers at Caltech. Result: the iconic image is far more spectacular than the original version.
So, why care other than for the aesthetics?
For scientists, taking pictures in space is like looking back into time. The farther away an astronomical object is, the longer it takes the light to reach us. In a practical sense, any light that we see coming from anything in the sky tonight left in direction proportion to its age. Example: for a star 500 light years away whose light we see tonight, that light left 500 years ago so, in essence, we are seeing how the star appeared 500 years ago. For another interesting thought, if that star were to blow itself up today, we would not know about it here on Earth for another 500 years, the time it would take the light from the explosion to reach us.
For scientists, this fact can prove insightful in determining the origins of galaxies and even the universe. With the UV assist, astronomers can now see galaxies that formed just a few hundred million years after the Big Bang, which created the universe as we know it. Why is this? Simple: visible light is blocked by interstellar gasses while UV light is not. In essence, by observing in UV, astronomers can lift a veil that would otherwise obscure the observable universe. By being able to see through such a wide swath of time, astronomers can study galaxies ta all stages of formation, which can then help determine why the universe is the way it is today.
Throughout its two decades in space, Hubble has undergone many refurbishments to keep the multimillion dollar space telescope up to speed with the technology on Earth. The most recent add-on: a new camera capable of operating in the infrared part of the electromagnetic spectrum. It is this ability to shoot in infrared that allows Hubble to see farther back in space and time than a visual light-only camera could ever could.
So, how do astronomers determine the distance of an object that is light years away? Answer: the Doppler Effect.
Everyone is familiar with the change in pitch that occurs when any object making a constant sound goes right past the observer. Example: a train is coming down the track and as it gets closer, the pitch increases, peaking as it passes you, then getting lower as it travels away. The reason it does this is because the sound waves are, relative to the stationary observer, getting compressed as the train nears and stretched out as it moves away. The same is true of light. In astronomy, scientists use the same technique, only with light waves, to measure distances to far away objects. The farther away something is, the more the light is shifted to the red (as opposed to the blue) end of the spectrum.
Now, with the extra UV light, scientists can now see farther back into time than visual light alone would ever allow.
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