Perseverance photographs Earth transit behind Mars moon Phobos

Rare perspective from Mars

On 2 July 2026, the Mastcam-Z camera on NASA’s Perseverance rover recorded a sequence in which Earth appears as a tiny, bright point seemingly passing behind the Martian moon Phobos. A composite made from seven individual frames shows the light spot moving from the upper left to the lower right. The images were taken on the mission’s 1,907th Martian day (Sol).

How the sequence was recorded

Mastcam-Z is a zoom-capable imaging system designed for geological and atmospheric studies. For this observation, the team aimed the optics toward the horizon and captured multiple exposures in quick succession. Exposure settings were tuned to the relatively faint brightness of Earth and Phobos, which is why background stars are barely visible.

What can be seen

Phobos appears as a dark, irregularly shaped object in the foreground. The small moon orbits Mars at low altitude in just a few hours; its surface looks rough and cratered. Behind it, Earth shows up as a point-like bright spot — at this distance effectively a single bright pixel.

Scientific value

The sequence aids camera calibration: reliably detecting such a small, distant target requires precise pointing and appropriate exposure. The observation also enables photometric measurements, for example of Phobos’s reflectance at different viewing angles. Those data provide clues about surface roughness and material properties and improve models of orbital dynamics and illumination geometry. Such measurements are also relevant for planned future investigations of the Martian moons.

Significance for Earth observation

Seeing Earth reduced to a light point illustrates the scale of the solar system and underscores the value of continuous Earth observation from space. Satellites deliver high temporal and spatial resolution data on the atmosphere, oceans, vegetation and ice sheets — the basis for reliably tracking global environmental and climate changes.

Geometry of the transit

The visible occultation is caused by the alignment of the rover, Phobos and Earth. Because Phobos is small and orbits Mars at low altitude, these configurations are not often documented from a rover’s perspective. In the image sequence the Earth point shifts while Phobos passes across the view.

Outlook

Perseverance remains a versatile tool: beyond the search for signs of past life and detailed analyses of the Martian surface, observations like this provide supplementary data that link engineering, science and the public.