【文章标题】：Moon (2024)
【文章标题】：月球（2024年）
【文章正文】：
【文章正文】：
Moon
月球
In the vastness of empty space surrounding Earth, the Moon is our closest celestial neighbor. Its face, periodically filled with light and devoured by darkness, has an ever-changing, but dependable presence in our skies.
在环绕地球的浩瀚虚空中，月球是我们最近的天体邻居。它的表面周期性地被光照亮，又被黑暗吞噬，在我们的天空中有着不断变化却又可靠的存在。
In this article, we’ll learn about the Moon and its path around our planet, but to experience that journey first-hand, we have to enter the cosmos itself.
在本文中，我们将了解月球及其绕地球运行的路径，但要亲身体验这段旅程，我们必须进入宇宙本身。
Let’s take a look at the Moon as seen from space in all its sunlit glory. You can drag it around to change your point of view, and you can also use the slider to control the date and time:
让我们来看看从太空中看到的、沐浴在阳光下的月球。你可以拖动它来改变视角，还可以使用滑块控制日期和时间：
In this convenient view, we can freely pan the camera around to see the Moon and its marvelous craters and mountains from various angles. Unfortunately, we don’t have that freedom of motion in our daily experience â the Moon wanders on its own path across the daily and nightly skies.
在这个方便的视图中，我们可以自由地平移相机，从各个角度观察月球及其壮观的陨石坑和山脉。遗憾的是，我们在日常体验中并没有这种移动的自由——月球沿着自己的路径在白天和夜晚的天空中游走。
We can simulate these travels below, where you can see the current position of the Moon in the sky. You can drag that panorama around to adjust your viewing direction â this lets you see the breadth of the sky both above and below the horizon. By dragging the sliders you can witness how the position of the Moon changes in the sky across days and hours of your local time. As the Moon’s placement in the sky shifts, the little arrow will guide you to its position.
我们可以在下面模拟这些运行，你可以看到月球当前在天空中的位置。你可以拖动全景图来调整观看方向——这让你能看到地平线以上和以下的广阔天空。通过拖动滑块，你可以观察月球在天空中的位置如何随着本地时间的日复一日、时复一时而变化。当月球在天空中的位置移动时，小箭头会指引你找到它的位置。
You can also drag the little figurine on the globe in the bottom-right corner to see how the sky looks at that location on Earth. If your browser allows it, clickingtapping the button will automatically put the figurine at your current location. This may all feel quite overwhelming at the moment, but we’ll eventually see how all these pieces fit together:
你还可以拖动右下角地球上的小人偶，看看地球上那个位置的天空是什么样子。如果你的浏览器允许，点击/轻触按钮会自动将人偶放到你当前的位置。目前这一切可能让人感到不知所措，但我们最终会看到这些部分是如何组合在一起的：
Over the course of one day, the Moon travels on an arc in the sky almost completing a loop around the Earth. As the days pass, the Moon’s illumination also visibly changes.
在一天的时间里，月球在天空中沿弧线运行，几乎绕地球完成一圈。随着日子一天天过去，月球的照明也发生明显变化。
You’ll probably admit that it’s a little hard to focus on the tiny Moon as it shifts its position in the sky. To make things easier to see, I’ll zoom in the camera and lock its position on the Moon:
你可能会承认，当小小的月球在天空中移动位置时，很难将注意力集中在它身上。为了看得更清楚，我会拉近相机并将其锁定在月球上：
Notice that across a single day the Moon seems to rotate, and over many days it quite visibly wobbles. These wobbly variations let us occasionally see some hidden parts on the “edges” of the Moon, but our neighbor ultimately shows us only one of its sides. In our space-floating demo we could easily see the Moon from all sides, but on Earth we can never see most of the far side of the Moon.
请注意，在一天之内，月球似乎在旋转，而在许多天里，它会明显地摆动。这些摆动变化让我们偶尔能看到月球“边缘”的一些隐藏部分，但我们的邻居最终只向我们展示它的一面。在我们的太空漂浮演示中，我们可以轻松地从各个侧面看到月球，但在地球上，我们永远看不到月球背面的大部分。
Over the course of days, the lighting on the Moon also changes dramatically. The line between the lit and unlit parts of the Moon, known as the terminator, sweeps across the Moon, revealing the details of its surface. Although the Moon has a spherical shape, the fully lit Moon looks more like a flat disk.
在数天的时间里，月球上的光照也会发生剧烈变化。月球被照亮和未被照亮部分之间的分界线，称为明暗界线，扫过月球表面，揭示出其表面的细节。尽管月球是球形的，但完全被照亮的月球看起来更像一个扁平的圆盘。
In this article I’ll explain all the effects we’ve just seen, and we’ll also learn about gravity, ocean tides, and eclipses. Let’s begin by exploring how celestial bodies move through space and how their mere presence influences the motion of their neighbors.
在本文中，我将解释我们刚刚看到的所有现象，我们还将了解重力、海洋潮汐和日食月食。让我们首先探索天体如何在太空中运动，以及它们的存在本身如何影响邻近天体的运动。
Motion in Space
太空中的运动
Let me introduce a little cosmic playground in which we’ll do our experiments. Inside it, I put a little planet that floats freely in space. You can drag the planet around to change its position. The arrow symbolizes the initial velocity of this body â you can tweak this velocity by dragging the dashed outline at the end of the arrow. To get things going, you can press the button in the bottom-left corner:
让我介绍一个小小的宇宙游乐场，我们将在其中进行实验。我在里面放了一颗在太空中自由漂浮的小行星。你可以拖动这颗行星来改变它的位置。箭头表示这个天体的初始速度——你可以通过拖动箭头末端的虚线轮廓来调整这个速度。要开始运行，你可以按下左下角的按钮：
Notice that I’m drawing a ghost trail behind the moving planet, making it easier to track its motion. As you can see, once you let the planet go, it travels through space in a straight line, only to eventually get out of visible bounds.
请注意，我在移动的行星后面画了一条幽灵轨迹，以便更容易跟踪它的运动。正如你所看到的，一旦你放开行星，它就会沿直线穿过太空，最终离开可见范围。
Let’s complicate things a little by adding another body to this sandbox. You can tweak the positions and velocities of both bodies to see how their mutual presence impacts one another. I’m also marking the thin lines of trajectories that the bodies will take even before you let things go, making it easier to plan their motion:
让我们给这个沙盒添加另一个天体，让事情变得稍微复杂一些。你可以调整两个天体的位置和速度，看看它们彼此的存在如何相互影响。我还会标出天体将要运行的细轨迹线，甚至在你放手之前就能看到，从而更容易规划它们的运动：
The motion we see now isn’t as straightforward as before. In some scenarios, the two bodies travel past each other after tweaking their initial trajectories. In other configurations, both objects roam through space together, permanently locked in a swinging dance.
我们现在看到的运动不像之前那么直截了当。在某些情况下，调整初始轨迹后，两个天体会相互擦肩而过。在其他配置中，两个天体一起在太空中漫游，永远锁定在摇摆的舞蹈中。
You may have also managed to make the two bodies run into each other. We’ll eventually see a more realistic visualization of that scenario, but in this simplified simulation when two objects collide, they just stick together and continue their coupled journey.
你可能还设法让两个天体撞到了一起。我们最终会看到那种场景的更真实可视化，但在这个简化的模拟中，当两个天体碰撞时，它们只是粘在一起，继续它们相伴的旅程。
What’s responsible for all these effects is the force of gravity acting on the objects. Let’s explore that interaction up close. As before, you can drag the two bodies around, and you can also change their masses using the sliders below:
造成所有这些现象的原因是作用在物体上的重力。让我们近距离探索这种相互作用。和之前一样，你可以拖动这两个天体，还可以使用下面的滑块改变它们的质量：
The arrows represent the force of gravity acting on the two bodies â the longer the arrow, the larger the force. For completeness, I’m displaying the values and units of masses and distances, but the numb
箭头表示作用在两个天体上的重力——箭头越长，力越大。为了完整起见，我展示了质量和距离的数值和单位，但数字