... SUN MOON MERCURY VENUS MARS, JUPITER SATURN . ... Mars . ... Year of Pluto . ... Durable NASA rover beginning ninth year of Mars work . ... Eight years after landing on Mars for what was planned as a three-month mission, NASAт??s enduring Mars Exploration Rover Opportunity is working on what essentially became a new mission five months ago. ... Mars years last nearly twice as long as Earth years. Entering its ninth Earth year on Mars, Opportunity is also heading into its fifth martian winter. ...