The planet Mars has gone through an ice age and is now warming up, scientists say.
科学家表示，火星已经脱离了冰河时代，现在正在升温。
The findings are based on detailed radar measurements of ice caps on Mars.
这些发现是基于对火星冰冠的详细雷达测定数据。
Isaac Smith studies the physical qualities of Earth and other planets -- or geophysics -- at the University of Texas. He told VOA about new research from scientists at universities in Texas, Colorado and Missouri.
艾萨克·史密斯（Isaac Smith）在得克萨斯大学研究地球物理。他对美国之音谈到了得克萨斯州、科罗拉多州以及密苏里州各个大学的科学家进行的新研究。
Their findings were published in the journal Science.
他们的研究结果发表在《科学》杂志上。
Smith said Mars has ice ages, just like Earth has had.
史密斯表示火星也和地球一样有过冰河时期。
"The last ice age... would have been about 600,000 years ago," he told VOA. "And the next [ice age on Mars] is 500,000 [years] in the future."
他对美国之音表示，“火星上一次冰河时期大约是60万年前，而下一次冰河时期是50万年后。”
Mars is often called the red planet. But, a few hundred thousand years ago, the scientists said, the planet was not so red. Their research suggests that Mars has been warming for the past 370,000 years.
火星通常被称之为红色星球。但是科学家表示，几十万年前火星没有这么红。他们的研究表明，过去37万年火星一直在升温。
Smith said ice may have built up to a thickness of several meters around Mars during its ice ages. This would have made the red planet look more white than red.
史密森表示，在冰河时期，冰层可能环绕火星表面堆积了几米高的厚度，这会让火星看上去更像白色而不是红色。
Smith told VOA an ice age on Mars would be different than an ice age on Earth. He said, during Martian ice ages, the north and south poles would be warmer than they are now, and they would have less ice.
史密斯对美国之音表示，火星上的冰河时期同地球上的冰河时期有所不同。他说，在火星冰河时期，南北两极可能会比目前更暖和，并且可能冰更少。
Warmer poles, he said, mean there would be more water in the atmosphere. The tilt and orbit of Mars and its thin atmosphere also would have a big impact on its ice ages.
他说，两极更暖和意味着空气中可能有更多水分。火星的斜度和轨道以及它的稀薄大气可能也会对其冰河时期产生很大的影响。
Scientists are attempting to understand how Mars has changed over long periods of time. The information they gather will help scientists look for evidence of life beyond Earth.
科学家们正在试图了解火星在很长一段时期内是如何变化的。他们收集到的信息将有助于科学家寻找地球以外生命的证据。
One of the keys to life is water. The scientists said their evidence suggests Mars could have been a watery place.
生命的关键之一是水。科学家表示，他们有证据表明火星过去可能是个水乡。
I'm Mario Ritter.
我是马里奥·理特。(51VOA.COM对本文翻译保留全部权利，未经授权请勿转载，违者必究！)