Passage 104 (4/17)-T140

主题句：New observations about the age of some globular clusters in our Milky Way galaxy (Milky Way galaxy: n.[天]银河系) have cast doubt on a long-held theory about how the galaxy was formed. The Milky Way contains about 125 globular clusters (compact groups of anywhere from several tens of thousands (tens of thousands: 好几万) to perhaps a million stars) distributed in a roughly spherical halo around the galactic nucleus (galactic nucleus: [天]星系核). The stars in these clusters are believed to have been born during the formation of the galaxy, and so may be considered relics of the original galactic nebula (galactic nebula: n.[天]银河星云), holding vital clues to the way the formation took place.原因：星星产生于星座形成时。 第一段：对星星年龄的观察否定了旧的星座形成理论。原因。

The conventional theory of the formation of the galaxy contends that roughly 12 to 13 billion years ago the Milky Way formed over a relatively short time (about 200 million years) when a spherical cloud of gas collapsed under the pressure of its own gravity into a disc surrounded by a halo. Such a rapid formation of the galaxy would mean that all stars in the halo should be very nearly the same age.老观点：星座形成的时间短，说明星星年龄相似

However, the astronomer Michael Bolte has found considerable variation in the ages of globular clusters. One of the clusters studied by Bolte is 2 billions years older than most other clusters in the galaxy, while another is 2 billion years younger. A colleague of Bolte contends that the cluster called Palomar 12 is 5 billion years younger than most other globular clusters.

第三段：B的观察：星星年龄差据大，否定了老观点。

To explain the age differences among the globular clusters, astronomers are taking a second look at “renegade” theories. One such newly fashionable theory, first put forward by Richard Larson in the early 1970’s, argues that the halo of the Milky Way formed over a period of a billion or more years as hundreds of small gas clouds drifted about, collided, lost orbital energy, and finally collapsed into a centrally condensed elliptical system. Larson’s conception of a “lumpy and turbulent” protogalaxy is complemented by computer modeling done in the 1970’s by mathematician Alan Toomre, which suggests that closely interacting spiral galaxies could lose enough orbital energy to merge into a single galaxy.RL提出新观点：星座形成的时间长。被子AT的计算机模型所证实。