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In the winter of 1995,
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scientists pointed the Hubble Telescope at an area of the sky near the Big Dipper,
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a spot that was dark and out of the way of light pollution from surrounding stars.
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The location was apparently empty, and the whole endeavor was risky.
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What, if anything, was going to show up?
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Over ten consecutive days,
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the telescope took close to 150 hours of exposure of that same area.
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And what came back was nothing short of spectacular:
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an image of over 1,500 distinct galaxies
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glimmering in a tiny sliver of the universe.
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Now, let's take a step back to understand the scale of this image.
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If you were to take a ballpoint pen
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and hold it at arm's length in front of the night sky,
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focusing on its very tip,
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that is what the Hubble Telescope captured in its first Deep Field image.
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In other words,
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those 3,000 galaxies were seen in just a tiny speck of the universe,
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approximately one two-millionth of the night sky.
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To put all this in perspective,
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the average human measures about 1.7 meters.
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With Earth's diameter at 12,700 kilometers,
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that's nearly 7.5 million humans lined up head to toe.
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The Apollo 8 astronauts flew a distance of 380,000 kilometers to the moon.
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And our relatively small Sun has a diameter of about 1.4 million kilometers,
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or 110 times the Earth's diameter.
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A step further,
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the Milky Way holds somewhere between 100 to 400 billion stars,
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including our Sun.
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And each glowing dot of a galaxy captured in the Deep Field image
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contains billions of stars at the very least.
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Almost a decade after taking the Deep Field image,
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scientists adjusted the optics on the Hubble Telescope
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and took another long exposure over a period of about four months.
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This time, they observed 10,000 galaxies.
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Half of these galaxies have since been analyzed more clearly
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in what's known as the eXtreme Deep Field image,
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or XDF.
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By combining over ten years of photographs,
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the XDF shows galaxies so distant
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that they're only one ten-billionth the brightness
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that the human eye can perceive.
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So, what can we learn about the universe from the Deep Field images?
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In a study of the universe, space and time are inextricably linked.
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That's because of the finite speed of light.
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So the Deep Field images are like time machines to the ancient universe.
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They reach so far into space and time
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that we can observe galaxies that existed over 13 billion years ago.
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This means we're looking at the universe as it was
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less than a billion years after the Big Bang,
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and it allows scientists to research galaxies in their infancy.
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The Deep Field images have also shown that the universe is homogeneous.
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That is, images taken at different spots in the sky look similar.
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That's incredible when we think about how vast the universe is.
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Why would we expect it to be the same across such huge distances?
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On the scale of a galaxy, let alone the universe,
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we're smaller than we can readily comprehend,
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but we do have the capacity to wonder,
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to question,
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to explore,
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to investigate,
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and to imagine.
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So the next time you stand gazing up at the night sky,
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take a moment to think about the enormity of what is beyond your vision,
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out in the dark spaces between the stars.