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  • In the winter of 1995,

  • scientists pointed the Hubble Telescope at an area of the sky near the Big Dipper,

  • a spot that was dark and out of the way of light pollution from surrounding stars.

  • The location was apparently empty, and the whole endeavor was risky.

  • What, if anything, was going to show up?

  • Over ten consecutive days,

  • the telescope took close to 150 hours of exposure of that same area.

  • And what came back was nothing short of spectacular:

  • an image of over 1,500 distinct galaxies

  • glimmering in a tiny sliver of the universe.

  • Now, let's take a step back to understand the scale of this image.

  • If you were to take a ballpoint pen

  • and hold it at arm's length in front of the night sky,

  • focusing on its very tip,

  • that is what the Hubble Telescope captured in its first Deep Field image.

  • In other words,

  • those 3,000 galaxies were seen in just a tiny speck of the universe,

  • approximately one two-millionth of the night sky.

  • To put all this in perspective,

  • the average human measures about 1.7 meters.

  • With Earth's diameter at 12,700 kilometers,

  • that's nearly 7.5 million humans lined up head to toe.

  • The Apollo 8 astronauts flew a distance of 380,000 kilometers to the moon.

  • And our relatively small Sun has a diameter of about 1.4 million kilometers,

  • or 110 times the Earth's diameter.

  • A step further,

  • the Milky Way holds somewhere between 100 to 400 billion stars,

  • including our Sun.

  • And each glowing dot of a galaxy captured in the Deep Field image

  • contains billions of stars at the very least.

  • Almost a decade after taking the Deep Field image,

  • scientists adjusted the optics on the Hubble Telescope

  • and took another long exposure over a period of about four months.

  • This time, they observed 10,000 galaxies.

  • Half of these galaxies have since been analyzed more clearly

  • in what's known as the eXtreme Deep Field image,

  • or XDF.

  • By combining over ten years of photographs,

  • the XDF shows galaxies so distant

  • that they're only one ten-billionth the brightness

  • that the human eye can perceive.

  • So, what can we learn about the universe from the Deep Field images?

  • In a study of the universe, space and time are inextricably linked.

  • That's because of the finite speed of light.

  • So the Deep Field images are like time machines to the ancient universe.

  • They reach so far into space and time

  • that we can observe galaxies that existed over 13 billion years ago.

  • This means we're looking at the universe as it was

  • less than a billion years after the Big Bang,

  • and it allows scientists to research galaxies in their infancy.

  • The Deep Field images have also shown that the universe is homogeneous.

  • That is, images taken at different spots in the sky look similar.

  • That's incredible when we think about how vast the universe is.

  • Why would we expect it to be the same across such huge distances?

  • On the scale of a galaxy, let alone the universe,

  • we're smaller than we can readily comprehend,

  • but we do have the capacity to wonder,

  • to question,

  • to explore,

  • to investigate,

  • and to imagine.

  • So the next time you stand gazing up at the night sky,

  • take a moment to think about the enormity of what is beyond your vision,

  • out in the dark spaces between the stars.

In the winter of 1995,

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TED-ED】宇宙の規模はどれくらい小さいのか?- アレックス・ホフェルト (【TED-Ed】How small are we in the scale of the universe? - Alex Hofeldt)

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    Wanning Wu に公開 2021 年 01 月 14 日
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