火卫一，火卫二与火星

2020年10月30日

Fear and Dread: The Moons of Mars
Composite Image Credit & Copyright: Dennis Simmons

Explanation: On Halloween fear and dread will stalk your night skies, also known as Phobos and Deimos the moons of Mars. The 2020 opposition of Mars was on October 13, so the Red Planet will still rise shortly before sunset. Near Halloween’s Full Moon on the sky, its strange yellowish glow will outshine other stars throughout the night. But the two tiny Martian moons are very faint and in close orbits, making them hard to spot, even with a small telescope. You can find them in this carefully annotated composite view though. The overexposed planet’s glare is reduced and orbital paths for inner moon Phobos and outer moon Deimos are overlayed on digitally combined images captured on October 6. The diminutive moons of Mars were discovered in August of 1877 by astronomer Asaph Hall at the US Naval Observatory using the Great Equatorial 26-inch Alvan Clark refractor.

Tomorrow’s picture: galaxy of horrors

火卫一、火卫二与火星
组合影像提供与版权: Dennis Simmons

说明: 在今年的万圣节，分别以恐惧和恐慌为名的火星卫星：火卫一及火卫二会在夜空中出没。虽然2020年火星冲是在10月13日，在目前火星仍然紧接在日落后东升。不过这二颗火星的小卫星，除了个头很小之外，轨道更是很近火星，因此用小望远镜很难见到它们的身影。然而在这幅详细加注的组合影像里，倒不难见到它们。在这幅摄于10月6日的组合影像里，过度曝光的火星之炫光经过衰减，并在图上叠合了较靠内的火卫一及较外的火卫二之轨道。这二颗火星小卫星，是在1877年8月由美国海军天文台的天文学家霍尔，使用66公分口径的克拉克折射式赤道仪大望远镜所发现。

明日的图片: galaxy of horrors