Messenger will explore the surface of Mercury, its crust, its atmosphere and even its magnetic field.

“信使号”将探索水星的表面、地壳、大气，甚至其磁场。

youdao

Titan was a major focus of the mission all along, since it's bigger than the planet Mercury and the only moon massive enough to have a significant atmosphere.

土卫六一直以来都是这项探测任务的主要聚焦点，因其体积比水星还要大，是唯一一颗拥有浓密大气层的卫星。

youdao

Mercury has no atmosphere to speak of, so there's no way for heat to circulate from the hot regions into the craters.

值得一提的是水星没有大气层，所以没有可以从高热量区向陨石流通的热能。

youdao

This was because they saw the black-drop effect in a transit of Mercury, a planet that has no atmosphere.

ECONOMIST: Transits of Venus

One of the chemical elements in Mercury's atmosphere is sodium, a gas somewhat easy to detect because it reflects sunlight very efficiently.

BBC: Close up on Mercury

Although coal does not often contain high concentrations of mercury, the authors say the "combination of the large volume burned and the fact that a significant portion of the mercury present is emitted into the atmosphere results in large overall emissions from the sector".

BBC: UN: Rising mercury emissions increase risk to humans