火卫一：注定灭亡的卫星

2022年7月3日

Phobos: Doomed Moon of Mars
Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA

Explanation: This moon is doomed. Mars, the red planet named for the Roman god of war, has two tiny moons, Phobos and Deimos, whose names are derived from the Greek for Fear and Panic. These martian moons may well be captured asteroids originating in the main asteroid belt between Mars and Jupiter or perhaps from even more distant reaches of our Solar System. The larger moon, Phobos, is indeed seen to be a cratered, asteroid-like object in this stunning color image from the robotic Mars Reconnaissance Orbiter, with objects as small as 10 meters visible. But Phobos orbits so close to Mars – about 5,800 kilometers above the surface compared to 400,000 kilometers for our Moon – that gravitational tidal forces are dragging it down. In perhaps 50 million years, Phobos is expected to disintegrate into a ring of debris.

Tomorrow’s picture: strawberry supermoon

火卫一：注定灭亡的卫星
影像提供: HiRISE, MRO, LPL (U. Arizona), NASA

说明: 这颗卫星在劫难逃。以罗马神话的战神为名的火星，有两颗名为火卫一和火卫二的小卫星，其名称的希腊文义分别是恐惧和恐慌。这两颗火星卫星，可能是火星和木星间小行星主带里的小行星，或者甚至是我们太阳系更外围的天体，后来被火星俘获。在这幅由火星探勘号轨道船所拍摄、最小可解析10米结构的彩色影像里，二者中较大的火卫一，也真的看起来酷似满布撞击坑的小行星。与月球和地球的间距400,000公里比起来，火卫一的轨道离火星表面非常近只有5,800公里，因此受到火星的潮汐力的下拉。也许在5千万年之内，火卫一就会崩解成为一个碎片环。

明日的图片: strawberry supermoon