你看到月全食了吗？高能的那种！

中国科学院国际合作局出品

Produced by Bureau of International Cooperation, Chinese Academy of Sciences

最近的月全食，你是否也抬头看到了那轮红红的血月？在我们的眼中，它是视觉盛宴；而在高能X射线波段，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.

为什么月亮会变红？

Why Does the Moon Turn Red?

月球绕地球公转，地球绕太阳公转。当月球进入地球的影子中，部分月面失去直射光，就出现了月食。地球大气吸收蓝、绿、黄光，只剩红光折射到月面，于是月全食时的月亮呈现红色，也就是我们看到的“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.

天关卫星如何“看”月全食？

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

月球本身不发光，它反射太阳光。月球的X射线辐射主要由太阳X射线激发月表元素产生。天关卫星通过监测这些X射线亮度变化，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.

天关卫星在地球轨道上运行，并不跟随月球移动。通过姿态控制系统，它可以将X射线望远镜始终指向月球，连续记录来自月球的X射线光子。

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.

当月球进入地球本影时，直射太阳X射线被挡，月球被激发产生的X射线明显减少，探测亮度下降。这就是X射线版本的“月食变暗”。

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.

红点从哪里来？

Where Do the Red Dots Come From?

天关卫星的X射线图中，每个红点都是一个被探测的光子，主要来自太阳X射线激发月球表面元素所产生的荧光辐射。月全食时红点减少，少量残余可能来自地球高层大气散射、地球磁尾的高能粒子与月球作用。

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.

天文与高能的完美结合

Astronomy Meets High-Energy Physics

在我们眼中，月全食是血月；在天关卫星眼中，它是一场天然空间实验：太阳是光源，月球是反射屏幕，地球影子是遮挡器。科学家借此研究地月物质和能量交换，分析地球磁尾与月球的相互作用并验证模型，甚至还可标定仪器。

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.

下次抬头看血月时，不妨想一想：地球轨道上的天关卫星，也正静静“看着”这轮高能版的红月亮。

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.