How far can Hubble telescope observe? What is its shooting principle?

Hubble telescope can observe far away. The question is reversed. Why did it take us so many billions of years to see the distance of 1000 billion light years? Light-year is the unit of length, and 1000 billion light-year refers to the distance traveled by light in 1000 billion years. You may think that since the celestial body is 10 billion light years away, it will take 10 billion years for our "sight" to fly to the celestial body and see it. In fact, this understanding is completely wrong. To see the true face of an object clearly, we can only see it because the light it emits or reflects is captured by a telescope or an eye, and then the light signal is imprinted.

Hubble Space Telescope can see far away, even more than 100 light years, because the light from celestial bodies 100 billion years ago has spread far to reach us. But the light from such a distant object is so dim that it takes the Hubble Space Telescope several months to collect enough light for imaging. Because the universe is expanding, an object beyond 1000 billion light years is retreating at the speed of 2 15000 km/s, or 7 1.6%, according to the Hubble constant of 70 (km/s)/MPa. At present, it takes more than10000000000 years for light from an object with1000000000 light years to reach the earth, because the space is expanding, and the light has already passed over1000000000000 light years.

People's eyes can see the universe, because our eyes receive all photons, not the eyes looking for photons, but the eyes of photons, so the image I saw 100 light years away was the light flying to Hubble 100 light years away, and finally we saw it in the mirror, instead of crossing 100 light years away to find the light there.

Compared with the universe, the speed of light is very slow, which means that what we see outside 10 billion light-years is only a repeat of 10 billion years ago. We never know what that star field looks like now, what it will look like in the future, and even the galaxy we see now 10 billion years ago no longer exists. But it will take 654.38+0 billion years to know. For celestial bodies over 65.438+0.4 billion light years, their current light will never reach the distance of the earth, which means that we will never see these distant celestial bodies. However, in the past, the light of these distant objects still reached the earth, so we can only see their past appearance, not their present or future appearance.