1 . Scientists have observed a planet being swallowed by its host star for the first time. They believe this could be a preview of what could one day happen to Earth — but don’t worry, that won’t be for about another five billion years.
The US astronomers said that when the sun finally does swallow Earth, it will cause only a “tiny change” compared to the cosmic (宇宙的) explosion they just witnessed. Most planets are believed to meet their end when their host star runs out of energy, turning into a red giant that massively expands, destroying anything unlucky enough to be in its path.
Astronomers had previously seen the before-and-after effects of this process, but had never caught a planet in the act of being consumed. Lead researcher Kishalay De said the accidental discovery unfolded like a “detective story”.
“It all started about three years ago when I was looking at data from the Zwicky Transient Facility survey, which took images of the sky every night,” Dr. De said.
He came across a star that had suddenly increased in brightness by more than 100 times over a 10-day period. The star is in the Milky Way galaxy (银河系), around 12,000 light years from Earth near the Aquila constellation (天鹰座). Dr. De had been searching for binary star (双星) systems, in which the larger star takes bites out of its companion, creating incredibly bright explosions called outbursts. But data showed that this outburst was surrounded by cold gas, suggesting it was not a binary star system.
And NASA’s infra-red space telescope NEOWISE showed that dust had started to shoot out of the area months before the outburst. More puzzling still was that the outburst produced around 1,000 times less energy than previously observed mergers (合并) between stars.
1. What is paragraph 2 mainly about?| A．US astronomers are concerned about the future of Earth. |
| B．The harm the cosmic explosion may bring. |
| C．A prediction made by US astronomers about Earth. |
| D．Harmony between the Earth and the Sun is of great importance. |
| A．He loves detective stories. | B．His efforts paid off at last. |
| C．The survey made him suffer. | D．He took pride in his discovery. |
| A．It is near the Aquila constellation. | B．It has the strongest brightness. |
| C．It can swallow other host stars. | D．It causes explosions constantly. |
| A．Science. | B．Literature. | C．Documentary. | D．Education. |
