[ti:Arrokoth: Most Distant Space Object Ever Explored] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]A space object billions of kilometers away from Earth is giving scientists information about how our planet, and others, were formed. [00:14.88]It is the most distant object ever explored by a spacecraft. [00:21.76]It is named Arrokoth, and sometimes called "Snowman" because of its shape. [00:29.84]Arrokoth is some 6.6 billion kilometers away from us. [00:37.12]It can be found about 1.6 billion kilometers past Pluto, the largest dwarf planet in our solar system. [00:50.16]NASA's New Horizons spacecraft flew past Arrokoth on New Year's Day, 3 years after exploring Pluto, [01:01.32]which is located just past the planet Neptune in an area called the Kuiper Belt. [01:09.92]The New Horizons spacecraft has been providing scientists with information about the formation of Neptune and other planets. [01:21.80]Pictures it sent back of Arrokoth show a reddish surface. It appears to be largely smooth, [01:32.08]with some craters—areas that are lower than their surroundings. [01:38.08]It is covered with frozen methanol, a kind of alcohol, and unidentified complex organic molecules. [01:50.16]Arrokoth is a small body -- 36 kilometers long and 20 kilometers wide. [01:58.80]It is classified as a planetesimal — objects that were among the original building blocks of our solar system. [02:10.72]Scientists believe these small bodies came together about 4.5 billion years ago. [02:20.48]They are thought to be an important middle size step on the way to building planets. [02:30.24]The space object is made of two round parts joined together, notes John Spencer, [02:37.84]an astronomer at the Southwest Research Institute in Colorado. [02:45.04]They "appear to have formed in orbit around each other from a local dust cloud, [02:53.32]which collapsed under its own gravity within the solar nebula [03:00.36]- the huge disk of dust and gas that the solar system formed from," he said. [03:10.44]The two parts then came together "very gently." [03:15.08]This suggests that planetesimals formed in local conditions in which crash speeds were slow, [03:26.04]instead of widely spaced objects coming together at high speeds. [03:33.92]"So we now have a clearer picture of how planets, including the Earth, were built," Spencer said. [03:43.04]He helped prepare a report on the study, which appeared in Science magazine. [03:50.52]When spacecraft visited planetesimals before, they were all badly damaged by objects that struck them. [04:01.08]Some experienced extreme heat because they moved too close to the sun. [04:09.68]"So it is thrilling to finally be able to see one still pretty much just as it was [04:18.72]after its formation," said Will Grundy, who is working with the New Horizons project. [04:27.76]He is a planetary scientist and study co-author from Lowell Observatory in Arizona. [04:38.08]One of the scientists on the New Horizons team is better known for his music [04:45.12]than his doctorate—an advanced degree in astrophysics. [04:51.88]Brian May, lead guitarist for the British group Queen, is passionate about space exploration, as well as music. [05:03.60]He wrote this song for the New Horizons project: [05:08.20](Music plays) [05:15.56]New Horizons will examine other objects in the Kuiper Belt from afar as it makes its way deeper into space. [05:29.12]I'm Anne Ball. [05:30.92](Music plays) 更多听力请访问51VOA.COM