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I am holding something remarkably old. It is older than any human artifact,
我拿著的是一個(gè)十分古老的東西。它比任何一個(gè)人工制品都要古老，
older than life on Earth, older than the continents and the oceans between them.
比地球上的生命古老，也比大陸和它們之間的海洋古老。
This was formed over four billion years ago in the earliest days of the solar system while the planets were still forming.
它形成于四十億年前，在太陽(yáng)系最初階段行星還在形成的過(guò)程中。
This rusty lump of nickel and iron may not appear special, but when it is cut open,
這一塊粗糙的鎳鐵合金看起來(lái)并不特殊，但它一旦被切開(kāi)，
you can see that it is different from earthly metals. This pattern reveals metallic crystals that can only form out in space
你就會(huì)發(fā)現(xiàn)它與地球上的金屬有很大不同。這種花紋意味著只能在外太空形成的金屬晶體，
where molten metal can cool extremely slowly, a few degrees every million years.
在那里融化的金屬能以極慢的速度冷卻，每百萬(wàn)年下降幾度。
This was once part of a much larger object, one of millions left over after the planets formed.
它曾經(jīng)是一個(gè)巨大物體的一部分，是在星球形成后存留下來(lái)的百萬(wàn)塊中的一個(gè)。
We call these objects asteroids. Asteroids are our oldest and most numerous cosmic neighbors.
我們稱(chēng)這些物體為小行星。小行星是我們已知的最古老數(shù)量最多的宇宙鄰居。
This graphic shows near-Earth asteroids orbiting around the Sun, shown in yellow,
這張圖顯示了近地小行星繞太陽(yáng)運(yùn)行的軌道，用黃色標(biāo)出的部分，
and swinging close to the Earth's orbit, shown in blue.
同時(shí)在地球軌道附近轉(zhuǎn)動(dòng)的行星，用藍(lán)色標(biāo)出。
The sizes of the Earth, Sun and asteroids have been greatly exaggerated so you can see them clearly.
關(guān)于地球，太陽(yáng)以及小行星的大小被放大，所以大家能很清楚地看到。
Teams of scientists across the globe are searching for these objects,
全球許多科學(xué)家都在尋找這些東西，
discovering new ones every day, steadily mapping near-Earth space.
并且每天都有新的發(fā)現(xiàn)，穩(wěn)定分布在近地空間。
