Maybe someone smarter than me can answer a question that this picture prompted in my mind. How come Mars in just a pinprick in the sky for us looking at Mars from Earth, but a crescent is visible of the earth from the surface of Mars?
Edit: I am as dumb as I expected. Thanks for the responses, and a big fuck you to the person who shamed me for my ignorance. I'm glad that there was only one
Although, at a high enough zoom, Earth could also be a crescent.
Planets closer to the sun than you can be in a range of places relative to you and the sun, and so you can see parts of it that are illuminated and parts that are in shadow. Venus and Mercury can both be seen as crescents when viewed from the Earth
When you're looking at a planet further out than you are, you only see the part of the planet that's facing the sun because that's the same part that facing you. So from Earth, the planet Mars looks like a disc.
As has been said, the blue dot in the photo is earth, not the crescent.
But you also have to remember that earth is about twice the size of mars, so when they’re the same distance apart, earth will appear twice the size in the Martian sky then mars does for us.
Sun light. This photo looks like it was taken at dusk or dawn and it's dark enough to see the far side/day side of earth reflecting more than the night side.
It's not as noticeable for us with Venus because it's closer ie brighter and more reflective due to the atmosphere making it visibly white.