A、Because it is so luminous. B、Because it is broad. C、Because it is where the Heaven is. D、Because it is so remote from us. D因果关

We humans have found countless mysteries of the universe with which to occupy our minds over the centuries. We not only ask questions about what something is but we also want to know why it is.
    Ancient people invented elaborate mythological explanations to account for the mysterious things they saw. (26) Both the sky with its heavenly bodies and seemingly never-ending vastness and the seas with their great depths and power were, and still are, capable of filling people with feelings of fear and wonder. As ancient humans looked at the sky above them, one sight that intrigued them most was the Milky Way. They, of course, didn’t know that the strange, broad, luminous band of light across the sky is in reality composed of countless stars and planets located so far from the Earth that they cannot be seen individually by the naked eye. To the ancient Chinese it appeared as a luminous river, which they referred to as the River of Heaven or the Silver Stream. (27) Even though today we know what the Milky Way is, it remains equally mysterious in many ways because it is so remote from us. (28) It is no wonder that for those individuals who believe in UFOs, it seems a likely place from which they could have arisen. After all, we know so little about heavenly bodies.
    The power of the ocean is awesome. We hear of tidal waves that crash onto land, destroying everything in their path; we read accounts of lost ships over the centuries. Now, in the 21st century as we fly across the Pacific, we can’t help but feel a bit lonely and concerned as we think of that vast body of water below us.
26. How did ancient people account for those mysterious things they saw?
27. What did ancient Chinese people consider the Milky Way as?
28. Why is the Milky Way mysterious to humans even now?