1803 年 4 月，美国特使门罗与法国签订《路易斯安那购买条约》： 以1500万美元（约合今日 3.4 亿美元 ）购得从密西西比河到落基山脉的 82.8 万平方公里 土地。 一夜之间，美国的领土几乎翻倍，从“东部小国”变成横跨大陆的“潜在强国”。

NASA OSIRIS-REx sample collection event at Asteroid Bennu saw the spacecraft plunge its arm into the surface. Find out how ...

NASA's OSIRIS-APEX mission, which was one of 19 designated to be canceled by the Trump administration, has been saved from ...

NASA’s ambitious OSIRIS-APEX mission to study the asteroid Apophis has been spared from cancellation, but its future is far ...

Ryugu’s samples reveal that water activity on asteroids lasted far longer than scientists thought, possibly reshaping ...

In April 2029, Apophis is predicted by NASA to come within 32,000 kilometers (20,000 miles) of the Earth's surface. Closer ...

From how space rocks wobble to where to hit them, scientists are learning the fine art of asteroid deflection — and it could ...

According to a study conducted by University of Tokyo researchers, Ryugu maintained a "pristine record" of late water activity. By examining the lutetium and hafnium isotopes in their rock samples, ...

Scientists have found evidence of liquid water flowing through the asteroid Ryugu for over a billion years, challenging previous theories about water activity on asteroids.

Aidan O'Brien's three-year-old can land the Group One on Champions Day at Ascot while Big Mojo, Trawlerman, The Lion In ...

As per a study led by researchers from the University of Tokyo, Ryugu preserved a “pristine record” of late water activity. The team studied the isotopes of lutetium and hafnium in their rock samples, ...

The metal-coated asteroid Psyche may have had eruptions of molten iron and nickel on its surface. This situation was more ...