Scientists use James Webb Space Telescope to make 1st 3D map of exoplanet — and it's so hot, it rips apart water

科学家使用詹姆斯·韦伯太空望远镜制作首张系外行星的三维地图——它如此炙热，以至于能撕裂水分子

Astronomers have produced the first-ever three-dimensional map of a planet outside our solar system — WASP-18b — marking a major leap forward in exoplanet research.

天文学家首次绘制出了太阳系外行星——WASP-18b 的三维地图，这标志着系外行星研究取得了重大进展。

Using the James Webb Space Telescope, researchers applied a new technique called 3D eclipse mapping, or spectroscopic eclipse mapping, to track subtle changes in various light wavelengths as WASP-18b moved behind its star. These variations allowed scientists to reconstruct temperature across latitudes, longitudes and altitudes, revealing distinct temperature zones throughout the planet's atmosphere.

研究人员使用詹姆斯·韦伯太空望远镜，应用了一种名为三维日食成像（或光谱日食成像）的新技术，追踪 WASP-18b 穿过恒星背后时各光波长的微小变化。这些变化使科学家能够重建纬度、经度和高度上的温度分布，揭示出整个行星大气中的不同温度区域。

"If you build a map at a wavelength that water absorbs, you'll see the water deck in the atmosphere, whereas a wavelength that water does not absorb will probe deeper," Ryan Challener, a postdoctoral associate in Cornell’s Department of Astronomy and lead author of a study published on the research, said in a statement. "If you put those together, you can get a 3D map of the temperatures in this atmosphere."

康奈尔大学天文学系博士后、该研究的第一作者瑞安·查勒纳在一份声明中表示：“如果你在水吸收的波长下绘制地图，你将看到大气中的水层，而在水不吸收的波长下，将能够探测得更深。如果将这些信息结合起来，你就可以得到这片大气中温度的三维地图。”

WASP-18b is located about 400 light-years from Earth; it has roughly 10 times Jupiter's mass and completes an orbit of its host star in just 23 hours. Because it's so close to its star, temperatures in the planet's atmosphere reach nearly 5,000 degrees Fahrenheit (2,760 degrees Celsius). Those scorching conditions made it an ideal candidate for testing the new method of 3D temperature mapping.

WASP-18b距离地球约400光年；它的质量大约是木星的10倍，在短短23小时内完成其主星的轨道运行。由于它离恒星如此之近，这颗行星的大气温度达到了近5000华氏度（2760摄氏度）。这些灼热的条件使其成为测试3D温度测绘新方法的理想候选者。

The map revealed a bright central hotspot surrounded by a cooler ring on the planet's dayside — it has a tidally locked orbit, meaning that one side of the planet is always facing its star — demonstrating that the exoplanet's winds fail to distribute heat evenly across the atmosphere.

地图显示行星白昼面有一个明亮的中央热点，周围被较冷的环状区域环绕——它处于潮汐锁定轨道上，这意味着行星的一侧始终朝向恒星——这表明这颗系外行星的大气风无法均匀分配热量。

Remarkably, the hotspot showed lower water vapor levels than WASP-18b's atmospheric average. "We think that's evidence that the planet is so hot in this region that it's starting to break down the water," Challener said. "That had been predicted by theory, but it’s really exciting to actually see this with real observations."

值得注意的是，这个热点的水蒸气含量低于WASP-18b大气的平均水平。Challener说：“我们认为，这是该行星该区域温度如此之高，以至于开始分解水的证据。这一现象早在理论上就有预测，但能够通过真实观测真正看到，确实令人兴奋。”

This new 3D eclipse mapping technique will open many doors in exoplanet observations, as it "allows us to image exoplanets that we can't see directly, because their host stars are too bright," said Challener. As 3D eclipse mapping is applied to other exoplanets observed by Webb, "[w]e can start to understand exoplanets in 3D as a population, which is very exciting," he added.

Challener表示：“这种新的三维日食成像技术将在系外行星观测中打开许多大门，因为它‘让我们能够成像那些无法直接看到的系外行星，因为它们的宿主恒星太亮了’。”他补充说，随着三维日食成像技术应用于韦伯望远镜观测的其他系外行星，“我们可以开始以群体方式以三维来理解系外行星，这非常令人兴奋。”

The team's research was published in the journal Nature Astronomy on October 28, 2025.

该团队的研究于2025年10月28日发表在《自然天文学》杂志上。