At 80 minutes after sunset January 31, 2014, Curiosity Rover and Mars were about 160 million km (99 million miles) from Earth. Curiosity pointed a camera on the Mast-cam above the horizon in the direction of Earth and snapped this photo of the evening sky.
Closer view of the same photo. The small dot of Earth is a little above left of center.
Zoom the image and crop the section with Earth. See a dot just below Earth?
NASA’s Jet Propulsion Laboratory processed the image to show Earth above and Moon below.
Standing on Mars with normal vision, Earth and Moon could easily be seen with un-aided eyes.
A musical selection for your enjoyment.