树荫里的日食

树荫里的日食

ByNASA中文

2023年10月15日 An Eclipse Tree Image Credit & Copyright: Shawn Wyre Explanation: Yes, but can your tree do this? If you look closely at the ground in the featured image, you will see many images of yesterday’s solar eclipse — created by a tree. Gaps between tree leaves act like pinhole lenses and each create a small image of the partially eclipsed Sun visible in the other direction. The image was taken in Burleson, Texas, USA. Yesterday, people across the Americas were treated to a partial eclipse of the Sun, when the Moon moves in front of part of the Sun. People in a narrow band of Earth were treated to an annular eclipse, also called a ring-of-fire eclipse, when the Moon becomes completely engulfed by…

沙漠上空的日食

沙漠上空的日食

ByNASA中文

2023年10月1日 A Desert Eclipse Image Credit & Copyright: Maxime Daviron Explanation: A good place to see a ring-of-fire eclipse, it seemed, would be from a desert. In a desert, there should be relatively few obscuring clouds and trees. Therefore late December of 2019, a group of photographers traveled to the United Arab Emirates and Rub al-Khali, the largest continuous sand desert in world, to capture clear images of an unusual eclipse that would be passing over. A ring-of-fire eclipse is an annular eclipse that occurs when the Moon is far enough away on its elliptical orbit around the Earth so that it appears too small, angularly, to cover the entire Sun. At the maximum of an annular eclipse, the edges of the Sun can be…

红色精灵与绿树

红色精灵与绿树

ByNASA中文

2023年9月18日 The Red Sprite and the Tree Credit & Copyright: Maxime Villaeys Explanation: The sprite and tree could hardly be more different. To start, the red sprite is an unusual form of lightning, while the tree is a common plant. The sprite is far away — high in Earth’s atmosphere, while the tree is nearby — only about a football field away. The sprite is fast — electrons streaming up and down at near light’s speed, while the tree is slow — wood anchored to the ground. The sprite is bright — lighting up the sky, while the tree is dim — shining mostly by reflected light. The sprite was fleeting — lasting only a small fraction of a second, while the tree is durable…

彩虹树

彩虹树

ByNASA中文

2023年3月13日 Rainbow Tree Image Credit & Copyright: Eric Houck Explanation: What lies at the end of a rainbow? Something different for everyone. For the photographer taking this picture, for example, one end of the rainbow ended at a tree. Others nearby, though, would likely see the rainbow end somewhere else. The reason is because a rainbow’s position depends on the observer. The center of a rainbow always appears in the direction opposite the Sun, but that direction lines up differently on the horizon from different locations. This rainbow’s arc indicates that its center is about 40 degrees to the left and slightly below the horizon, while the Sun is well behind the camera and just above the horizon. Reflections and refractions of sunlight from raindrops…

极光与树

极光与树

ByNASA中文

2021年02月28日 The Aurora Tree Image Credit & Copyright: Alyn Wallace Explanation: Yes, but can your tree do this? Pictured is a visual coincidence between the dark branches of a nearby tree and bright glow of a distant aurora. The beauty of the aurora — combined with how it seemed to mimic a tree right nearby — mesmerized the photographer to such a degree that he momentarily forgot to take pictures. When viewed at the right angle, it seemed that this tree had aurora for leaves. Fortunately, before the aurora morphed into a different overall shape, he came to his senses and capture the awe-inspiring momentary coincidence. Typically triggered by solar explosions, aurora are caused by high energy electrons impacting the Earth’s atmosphere around 150 kilometers…