火星的Z字形逆行轨迹

火星的Z字形逆行轨迹

ByNASA中文

2023年4月15日 When Z is for Mars Image Credit & Copyright: Tunc Tezel (TWAN) Explanation: A composite of images captured about a week apart from mid August 2022 through late March 2023, this series traces the retrograde motion of ruddy-colored Mars. Progressing from lower right to upper left Mars makes a Z-shaped path as it wanders past the Pleiades and Hyades star clusters, through the constellation Taurus in planet Earth’s night sky. Seen about every two years, Mars doesn’t actually reverse the direction of its orbit to trace out the Z-shape though. Instead, the apparent backwards or retrograde motion with respect to the background stars is a reflection of the orbital motion of Earth itself. Retrograde motion can be seen each time Earth overtakes and laps…

2020年夏天的土星与木星

2020年夏天的土星与木星

ByNASA中文

2020年12月12日 Saturn and Jupiter in Summer 2020 Image Credit & Copyright: Tunc Tezel (TWAN), Onur Durma Explanation: During this northern summer Saturn and Jupiter were both near opposition, opposite the Sun in planet Earth’s sky. Their paired retrograde motion, seen about every 20 years, is followed from 19 June through 28 August in this panoramic composite as they wander together between the stars in western Capricornus and eastern Sagittarius. But this December’s skies find them drawing even closer together. Jupiter and Saturn are now close, bright celestial beacons in the west after sunset. On solstice day December 21 they will reach their magnificent 20 year Great Conjunction. Then the two largest worlds in the Solar System will appear in Earth’s sky separated by only about…