Planetary Picture of the Day - Week of June 22, 2026

Monday, 22 June 2026

Boulders Escaping Asteroid Dimorphos

This NASA/ESA Hubble Space Telescope image of the asteroid Dimorphos was taken on 19 December 2022, nearly four months after the asteroid was impacted by NASA’s DART (Double Asteroid Redirection Test) mission. Hubble’s sensitivity reveals a few dozen boulders knocked off the asteroid by the force of the collision. These are among the faintest objects Hubble has ever photographed inside the Solar System.

The ejected boulders range in size from 1 meter to 6.7 meters across, based on Hubble photometry. They are drifting away from the asteroid at around a kilometer per hour. The discovery yields invaluable insights into the behavior of a small asteroid when struck by a projectile, altering its trajectory.

Wednesday, 24 June 2026

A JunoCam View of Europa

Jupiter's moon Europa was captured by the JunoCam instrument aboard NASA's Juno spacecraft during the mission's close flyby on Sept. 29, 2022. As with our Moon and Earth, one side of Europa always faces Jupiter, and that is the side of Europa visible here. Europa's surface is crisscrossed by fractures, ridges, and bands, which have erased terrain older than about 90 million years.

Friday, 26 June 2026

Marvelous Martian Mega-Ripples

Mega-ripples are distinct wind-driven formations that occur on the surface of Earth and Mars, often with sizes between those of smaller ripples and larger dunes. Based on their shapes and examples of fractured crests in some areas, mega-ripples are thought to be largely inactive relics of past climates. Thanks to repeat coverage by HiRISE, we can tell that some mega-ripple fields are active and migrating alongside dunes and ripples.

From this downwind perspective, we can see mega-ripples forming along the flanks of the dark sand dunes near the North Polar deposits.

Landforms across these North Polar latitudes become ice-cemented when wintertime carbon dioxide ice buries dunes. Then the ice sublimates through the northern spring until dunes and mega-ripples become “frost-free” and mobile by summer. It is these summertime seasonal winds that drive the enhanced activity of migrating mega-ripples of the North Polar region.