This month, on the 18th, Mars reaches a position on the opposite side of the Sun that in astronomical terms is called a solar conjunction – or we would say that the Mars is in conjunction with the Sun. For the closest outer planet to the Earth Mars reaches solar conjunction approximately every 26 months. This is a result of the orbital periods for each planet and the time it takes for each planet to return to the same line up (Earth – Sun – Mars) or solar conjunction.
While observing Mars is obviously not possible during a solar conjunction, having Mars on the opposite side of the Sun also impacts the current Mars exploration programs. In particular mission controllers are unable to communicate with the various orbiters and rovers on or around Mars for a period of about one month, ending at the start of next month. During this time the orbiters and rovers are put in a sort of safe mode where the rovers, for example, stay in one spot, not moving until contact with mission control is re-established.
This animated graphic shows a view of the terrestrial planets at one-day intervals from April 4th to May 1st, the time period when radio communication is interrupted.
Click here to visit the Mars Curiosity Rover web site.
Click here to go to the Qué tal in the Current Skies web site for more observing information.