金星的位相

金星的位相

BySamuel Chan

2024年1月8日 The Phases of Venus Image Credit & License: Stéphane Gonzales Explanation: Venus goes through phases. Just like our Moon, Venus can appear as a full circular disk, a thin crescent, or anything in between. Venus, frequently the brightest object in the post-sunset or pre-sunrise sky, appears so small, however, that it usually requires binoculars or a small telescope to clearly see its current phase. The featured time-lapse sequence was taken over the course of six months in 2015 from Surgères, Charente-Maritime, France, and shows not only how Venus changes phase, but changes angular size as well. When Venus is on the far side of the Sun from the Earth, it appears angularly smallest and nearest to full phase, while when Venus and Earth are…

土耳其上空的双月行迹

土耳其上空的双月行迹

ByNASA中文

2022年10月10日 A Double Lunar Analemma over Turkey Image Credit & Copyright: Betul Turksoy Explanation: An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. But the trick to imaging an analemma of the Moon is to wait bit longer. On average the Moon returns to the same position in the sky about 50 minutes and 29 seconds later each day. So photograph the Moon 50 minutes 29 seconds later on successive days. Over one lunation or lunar month it will trace out an analemma-like curve as the Moon’s actual position wanders due to its tilted and elliptical orbit. Since the featured image was taken over two months, it actually shows…

2022年的月相

2022年的月相

ByNASA中文

2022年2月1日 Moon Phases 2022 Video Credit: Data: Lunar Reconnaissance Orbiter ; Animation: NASA’s Scientific Visualization Studio; Music: Build the Future (Universal Production Music), Alexander Hitchens Explanation: What will the Moon phase be on your birthday this year? It is hard to predict because the Moon’s appearance changes nightly. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The featured video animates images and altitude data taken by NASA’s Moon-orbiting Lunar Reconnaissance Orbiter to show all 12 lunations that appear this year, 2022 — as seen from Earth’s northern (southern) hemisphere. A single lunation describes one full cycle of our Moon, including all of its phases. A full lunation takes about 29.5 days, just under a…