Earth, the tiny bright spot above the Mars horizon, is so hard to see that it helps to also look at the version of the photo in which NASA has embedded a handy pointer. But perhaps Earth being just a tiny spot puts in perspective what it's like to be 99 million miles away.
According to NASA, "a human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright 'evening stars.' "
We'll put the new image and NASA's helpful illustrations in a gallery with other famous shots of Earth from far away.