中國科學院國際合作局出品

Produced by Bureau of International Cooperation, Chinese Academy of Sciences

最近的月全食，你是否也抬頭看到了那輪紅紅的血月？在我們的眼中，它是視覺盛宴；而在高能X射線波段，它又完全不同。

Did you look up and catch the recent total lunar eclipse—the red "Blood Moon"? To our eyes, it's a spectacular sight, but in high-energy X-rays, it looks completely different.

為什么月亮會變紅？

Why Does the Moon Turn Red?

月球繞地球公轉，地球繞太陽公轉。當月球進入地球的影子中，部分月面失去直射光，就出現了月食。地球大氣吸收藍、綠、黃光，只剩紅光折射到月面，于是月全食時的月亮呈現紅色，也就是我們看到的“血月”。

The Moon orbits the Earth while the Earth orbits the Sun. When the Moon passes through Earth's shadow, parts of it lose direct sunlight, creating a lunar eclipse. Earth's atmosphere absorbs blue, green, and yellow light, allowing only red light to bend onto lunar surface—hence the Blood Moon.

天關衛星如何“看”月全食？

How Does the Einstein Probe (Tianguan Satellite) "See" a Total Lunar Eclipse?

月球本身不發光，它反射太陽光。月球的X射線輻射主要由太陽X射線激發月表元素產生。天關衛星通過監測這些X射線亮度變化，就能捕捉“高能版的月全食”。

The Moon does not emit light on its own; it reflects sunlight. Its X-ray emission is mainly produced when solar X-rays excite elements on the lunar surface. By monitoring changes in X-ray brightness, the Einstein Probe (Tianguan Satellite) can capture the high-energy version of a total lunar eclipse.

天關衛星在地球軌道上運行，并不跟隨月球移動。通過姿態控制系統，它可以將X射線望遠鏡始終指向月球，連續記錄來自月球的X射線光子。

The satellite orbits Earth, not the Moon. Using its attitude control system, it keeps the X-ray telescope locked onto the Moon and continuously records X-ray photons coming from it.

當月球進入地球本影時，直射太陽X射線被擋，月球被激發產生的X射線明顯減少，探測亮度下降。這就是X射線版本的“月食變暗”。

When the Moon enters Earth's shadow, direct solar X-rays are blocked, X-rays generated from the lunar surface drop, and the detected brightness decreases—this is the X-ray version of the eclipse dimming.

紅點從哪里來？

Where Do the Red Dots Come From?

天關衛星的X射線圖中，每個紅點都是一個被探測的光子，主要來自太陽X射線激發月球表面元素所產生的熒光輻射。月全食時紅點減少，少量殘余可能來自地球高層大氣散射、地球磁尾的高能粒子與月球作用。

In EP's X-ray images, each red dot represents a detected photon. Most are fluorescent X-rays produced when solar X-rays excite elements on the lunar surface. During a total lunar eclipse, the number of red dots drops sharply. The remaining photons may come from X-rays scattered by Earth's upper atmosphere or from interactions between high-energy particles in Earth's magnetotail and the Moon.

天文與高能的完美結合

Astronomy Meets High-Energy Physics

在我們眼中，月全食是血月；在天關衛星眼中，它是一場天然空間實驗：太陽是光源，月球是反射屏幕，地球影子是遮擋器。科學家借此研究地月物質和能量交換，分析地球磁尾與月球的相互作用并驗證模型，甚至還可標定儀器。

To us, a total lunar eclipse is a Blood Moon. But to EP, it's a natural space experiment: the Sun serves as the light source, the Moon as a reflective screen, and Earth's shadow as a natural shutter. This precise geometry allows scientists to study the exchange of matter and energy between Earth and the Moon, explore interactions between Earth's magnetotail and the lunar environment, test theoretical models, and even calibrate instruments.

下次抬頭看血月時，不妨想一想：地球軌道上的天關衛星，也正靜靜“看著”這輪高能版的紅月亮。

Next time you look at a Blood Moon, remember: the Einstein Probe (Tianguan Satellite) in Earth orbit is quietly watching this high-energy version of the red Moon.