Clear Lake High School Rahul Yesantharao, Lekha Yesantharao, Eric

Chen, Anshuman Kumar, George Zhang

ExMASS Moon 101

Definitions • Impact Crater – Crater formed by a high-velocity impact • Rille – A fissure or channel on the moon • Mare – A large plain formed by cooled lava • Imbrium – A large mare formed from a large crater

Image 1

Image 1 Analysis • Image 1 portrays the crater-riddled lunar surface • Because they do not cast shadows, each circular formation

is a crater. • Three Formation Phases

– Compression Phase: the impactor transfers energy to the lunar surface and explodes.

– Excavation Phase: shockwave forms the crater. – Modification Phase: crater formation finalizes

• Craters in the top right of the image (circled in blue) are more defined and crisp than the other, faded craters.

• Only half-illuminated, implying that they are deep and the light cannot reach the left side.

Image 1

LIGHT

Image 1 Analysis • Left and bottommost craters are older • Lost definition as they eroded over time due to other

impacts, and have been filled with sediment from impacts, making them lose depth

• Because they have a more uniform depth, they catch no light and are darker and harder to see in the image.

Image 1

LIGHT

Image 2

Image 2 Analysis • Image 2 portrays Elbow Crater, which is part of the Hadley

Rille upon the Mare Imbrium, surrounded by impact craters. • Elbow Crater was formed as the rille was created from lava

flow channels. The tubes that were created from these flows subsequently collapsed to create the valley-like structure.

• The Mare Imbrium that the rest of the features are located upon was formed first when a large impact created a smooth lava flood plain. The Rille then formed second, before the craters, because the rille formed before major mare-forming volcanic activity ended (1 to 1.5 billion years ago), whereas well-defined craters were created by more recent impacts. So, the impact craters seen to the right side of the image were formed last.

Image 3

Image 3 Analysis • Image 3 portrays a sinuous rille, specifically Hadley Rille, channeling

through the Apenninus peaks. The flat area to the left is the Palus Putredinis.

• Hadley rille - conduit through which lava once; collapsed during mare volcanism.

• Apenninus mountains - possibly fault-block mountains, formed from crust displacement during impact that formed Mare Imbrium.

• Palus Putredinis - flooded lava plain, formed when lava pooled in the indent created by impact that formed Mare Imbrium.

• Palus Putredinis formed first because impact that formed the Mare Imbrium caused the smooth lava flood plain upon which other features formed.

• The Apenninus mountains formed next due to the segmentation of the crust due to the impact.

• The Hadley Rille, formed from lava channeling, creating a lava tube that collapsed to create the valley-like structure we see today.

• In the center area of the rille, there is a crater that appears to be obscuring part of the rille. This suggests that this crater is the most recently formed geologic feature, because the impact crater covers part of the older rille.

Image 3