While Mercury was quite active in its early days, it has been perceived as dead for a long time because of the static appearance of its surface.

Mercury is a planet that just doesn't make sense. It's incredibly small yet hosts a relatively massive core. Mercury is so strange that astronomers have not been able to explain its properties with ...

Far smaller and closer to the Sun than it should be, Mercury has long baffled astronomers because it defies much of what we know about planet formation. A new space mission arriving in 2026 might ...