When planets and other bodies revolve around the Sun, they usually revolve around the same plane. So chances are that they would apparently share the same declination or right ascension (or both) at some point in time. We call such event as a conjunction.
In other words, conjunction refers to the astronomical event where two astronomical bodies appear together or closer when seen from Earth. Such events occur when either of their celestial coordinates matches with one another.
Rare astronomical conjunctions
Though astronomical conjunctions happen more often, they usually have a much larger angular separation. Rare conjunctions are the events where the two bodies occult each other or when they are only separated by smaller angular distances.
In fact, at the time of this writing, a rare planetary conjunction just happened. Venus and Jupiter appeared closest to each other with a separation of 15.7 arcminutes (12 degrees). Here are some photographs of the 2017 Jupiter and Venus conjunction.
Here are some other photographs of similar conjunction events throughout time. Another rare moment waiting to happen is in the year 2065 where Venus would occult Jupiter. Probably by that time, we could get some staggering photographs.