Sinus iridum is what type of feature

Then, million years later, a large chunk of rock smashed into the the northern rim of the Imbrium depression. As a result, when we look there with our telescopes today, we see the vast expanse of Mare Imbrium and the lovely curve of Bay of Rainbows. If you train your scope on this region when the terminator sweeps across Sinus Iridum, the easternmost horn of the Bay, named Cape Laplace, first begins to catch the light of the approaching lunar dawn.

As the hours pass, more and more of the arc of the Jura Mountain lights up. Eventually, the whole curve of Sinus Iridum up to Cape Heraclides is bathed in bright sunlight, even as most of the flat Bay remains in darkness. This week, you have that chance. As with so many lunar features, its visibility is less a question of optics than it is of illumination.

Some years ago the waxing gibbous Moon was closely conjunct Jupiter. The weather that evening was clear, so I set up 15x70 binoculars on a tripod in front of my home and shared the view of the Moon, Jupiter, and Jupiter's moons with neighbors and passersby.

One grizzled older fellow asked me why there was a wire hanging off the edge of the Moon. I didn't understand his question until I looked for myself and noticed the edge of Sinus Iridum illuminated by sunlight while the surface of the bay was still in darkness. Eventually I was able to explain what he was seeing -- imagine you're looking up at a mountaintop at sunrise Log in to Reply. There is a recent theory by Schultz and Crawford that Sinus Iridum is the first contact point of an oblique protoplanet impact.

They estimate the impactor diameter is about kilometers. Now one can imagine a protoplanet making first contacting at Sinus Iridum and turning into a shotgun of debris as it collapses into the Moon! Schultz, Peter H.

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