At the beginning of Navaratri I watched the moon rise in the east through a thin haze of clouds. The atmosphere affects our view of the sky quite a bit. On the moon, the line of sunrise had just crossed the shores of the Sea of Crisis (Mare Crisium). The same sun that rises over the moon also rises on earth.
The next morning in Bera I watched the sun rise. The sky turned from black to red. And then, as the horizon fell away below the sun, the air turned blue and bright. On the airless moon will you only see the bright yellow sun pop over the horizon in an airless black sky? Interestingly, the sun creates its own drama as it rises over the moon. The solar wind kicks up dust in a narrow 150 km band around the terminator. Diffraction of sunlight through the dust will produce spectacular, albeit dimmer, colours. I can’t wait to see the first photos of the colours of sunrise from the moon.
Luna glided overhead as we looked for nightjars. It was easier to spot the triad of lunar seas, serenity, tranquility, fertility, than a savanna nightjar in flight. Certainly photographing them at night with my equipment was out of the question, even with the moon waxing to nearly three quarters. I turned my camera up to the moon.
The lunar seas of showers and of clouds had become visible a couple of days ago. These fancifully named seas are actually basalt shields, the frozen remnants of lava flows which were caused by an extensive bombardment by meteors around four billion years ago. The earth was also shaped by this shower, and very few fragments of continental crusts are older. Life began on earth soon after that. On the moon the lava seas in these enormous craters had solidified more than three billion years ago. By that time photosynthesis had begun on earth. Our atmosphere was changing even as the splotchy appearance of the moon took shape. The new photosynthetic life made the earth unlivable for most anaerobic bacteria and caused the first age of extinction.
Near the northern end of the terminator, my camera could pick out the far edge of Plato crater catching the morning sunlight. This crater is as old as the sea of showers (Mare Imbrium) just south of it. If you were to stand inside that crater then and looked up at the cliffs on the far edge, what a sight the morning sunlight must be! At the southern end of the terminator you can see a jumble of craters. Just inside it, at roughly mid-morning, is the bright young Tycho crater, only a 108 million years old. The dinosaurs may have seen it forming. In a few days, the whole of the visible half of the moon would have day. That lunar day is what we call a harvest moon. It was still more than a week away.
In the next two days we were to cross the Tropic of Cancer several times, as we scouted for more of the winter’s birds passing through the Rann of Kutch. It was a funny astronomical coincidence. The Tropic of Cancer marks the furthest point north where the sun can be at the zenith. And we were near that at the time the sun was crossing the equator! As I took photos of the signboard someone remarked that it had seen better days. True enough. So had the moon, by my reckoning.