Huge asteroid will pass closer to Earth than the moon

 　　BEIJING, Nov. 7 (Xinhuanet) -- A huge asteroid¹ will pass closer to Earth than the moon on Tuesday, but experts say there is no cause for alarm.

　　Asteroid 2005 YU 55 will pass about 300-thousand kilometers from the earth. The giant space rock is about 400 meters in diameter. The close encounter will occur at 23:28 Greenwich Mean Time. Computer models showing the asteroid’s path for the next 100 years show there is no chance it will hit Earth during that time.

　　Previous studies show the asteroid is what is called a C-type asteroid that is likely made of carbon-based materials and some silicate² rock.

1 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

2 silicate   

n.硅酸盐

参考例句：

• There are large amounts of aluminum silicate in the area.这个地区有大量的硅酸铝。
• Silicate minerals are characteristically refractory and difficult to break down.硅酸盐矿物的特点是耐熔和难以分离。