Impact melt forms a swirled feature in Giordano Bruno crater. Image width is 1 km, LROC NAC M143947267L [NASA/GSFC/Arizona State University].
The crater Giordano Bruno is a favorite of lunar scientists due to its relatively young age and the amazing impact melt features found within and without the crater walls. Previously, the LROC Featured Image gave a birds eye view of the whole crater in Giordano Bruno, The Big Picture. Today's Featured Image uses a 57 cm per pixel NAC frame to highlight the details of a giant swirl (or whorl) of impact melt within one of the larger impact melt pools inside Giordano Bruno. The whorl formed in a clockwise direction and is ~1 km in diameter. This spiral-shaped feature may have formed due to shear stress created when molten impact melt flowed at different speeds (probably caused by drag from the pool floor or an obstacle within the pool). This shear would modify flow directions in ways that could ultimately produce such a swirling pattern. Slumping material may have set the melt into motion within an otherwise calm impact melt pool. The more information lunar scientists can gather about how quickly impact melt cools, the more we will know about how this structure formed!
Context image of Giordano Bruno crater. The location of the Featured Image is in shadow along the western edge of the floor. Image width is 49 km [NASA/GSFC/Arizona State University].