That impact may also have been responsible for the odd terrain on the exact opposite side of the planet. In addition to its heavily cratered terrain, Mercury also has regions of relatively smooth plains. Some of the plains may be the result of ancient volcanic activity, but some may be deposits of dirt ejected from craters by impacts. A reanalysis of the old Mariner data revealed some evidence of recent volcano activity on Mercury. Mercury has a small magnetic field whose strength is about one percent of Earth's magnetic field.
Mercury often is visible from earth with binoculars and sometimes even the naked eye.
However, the planmet always is very near the Sun and difficult to see in the twilight sky. Planet finder charts show the sky position of Mercury and the other planets. A planetarium program such as Starry Night creates detailed custom charts. Mercury has no known satellites. No iron has been seen in spectroscopic studies of the planet's surface.