Aristoteles and Eudoxus are two of the largest young craters in the north polar region of the Moon. Aristoteles is 87 km wide and Eudoxus has a diameter of 67 km. These craters look pretty similar, both have terraced walls and hilly floors, apparently veneered with some smooth material - perhaps impact melt. Which is youngest? The larger crater has radial ejecta and secondary craters on nearby Mare Frigoris. These are seen more clearly on the Lunar Orbiter IV frame. Because Eudoxus formed on rubbly Imbrium ejecta, its secondary craters are harder to recognize. The US Geological Survey assigns Eudoxus a stratigraphic age of Copernican, whereas Aristoteles is Eratosthenian. This means that Eudoxus is younger than 1.1 billion years old, and Aristoteles is somewhere between 1.1 and 3.2 b.y. old. Since both craters have about the same number of superposed (subsequent) impact craters, the two craters must be very near the Copernican-Eratosthenian boundary, with one slightly older and the other slightly younger.
Technical Details:
Cristian's low Sun view was obtained May 25, 2004 when the seeing was excellent. He used a 25 cm Newtonian telescope with a Vesta Pro webcam; 300 out of 450 frames were combined with the IRIS software.
Related Links:
Aristoteles: Lunar Orbiter IV View
Eudoxus: Lunar Orbiter IV View
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