In astronomy, what does retrograde mean? And what connection does it have to astrology? We explain how planets move across ...

Learn how you can see bright Jupiter from Earth, helped by its massive size and banded, reflective cloud tops, in December's ...

Mercury retrograde is a fascinating natural phenomenon that can open your eyes to the inner workings of the solar system.

Mercury ' s inner core is solid and about the same size as Earth ' s inner core, a new study using observations from NASA's MESSENGER mission has indicated. Mercury is the smallest planet in our ...

At only a third the size of the Earth, Mercury had automatically become the smallest planet in our solar system, ripe for bullying by Jupiter and the other giants patrolling around our Sun.