Dread personified Tuesday Telescope: A rare glimpse of one of the smallest known moons I'll bet you don't spend a ton of time thinking about Deimos. Eric Berger – Apr 22, 2025 8:00 am | 9 Martian moon Deimos appears dark, framed by the brighter planet Mars behind it. Credit: European Space Agency Martian moon Deimos appears dark, framed by the brighter planet Mars behind it. Credit: European Space Agency Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only   Learn more Welcome to the Tuesday Telescope. There is a little too much darkness in this world and not enough light—a little too much pseudoscience and not enough science. We’ll let other publications offer you a daily horoscope. At Ars Technica, we’ll take a different route, finding inspiration from very real images of a universe that is filled with stars and wonder. I'll bet you don't spend a ton of time thinking about Deimos, the smaller of the two Martian moons, which is named after the Ancient Greek god that personified dread. And who could blame you? Of the two Martian moons, Phobos gets more attention, including as a possible waystation for human missions to Mars. Phobos is larger than Deimos, with a radius of 11 km, and closer to the Martian surface, a little more than 9,000 km away. By contrast, Deimos is tiny, with a radius of 6 km, and quite a bit further out, more than 23,000 km from the surface. It is so small that, on the surface of Mars, Deimos would only appear about as bright in the night sky as Venus does from Earth. But who doesn't love a good underdog story? Scientists have dreamed up all kinds of uses for Deimos, including using its sands for aerobraking large missions to Mars, returning samples from the tiny moon. So maybe Deimos will eventually get its day. Recently, we got one of our best views yet of the tiny moon when a European mission named Hera, en route to the asteroid Didymos, flew through the Martian system for a gravity assist. During this transit, the spacecraft came within just 300 km of Deimos. And its Asteroid Framing Camera captured this lovely image, which was, admittedly, artificially colored. Anyway, it's a rare glimpse at one of the smallest known moons in the Solar System, and I think it's spectacular. Source: European Space Agency Do you want to submit a photo for the Daily Telescope? Reach out and say hello. Eric Berger Senior Space Editor Eric Berger Senior Space Editor Eric Berger is the senior space editor at Ars Technica, covering everything from astronomy to private space to NASA policy, and author of two books: Liftoff, about the rise of SpaceX; and Reentry, on the development of the Falcon 9 rocket and Dragon. A certified meteorologist, Eric lives in Houston. 9 Comments