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Moon and Venus
There are no oceans or seas on Venus, so there’s no sea level for measuring the height or depth of mountains, canyons, or other features. Instead, scientists calculate an average elevation, then measure any deviations from that. And what they’ve found is that most of the planet’s surface is remarkably smooth and flat.
The entire surface was shaped by volcanoes and volcanic events. In fact, there’s evidence that the whole planet was repaved by molten rock a few hundred million years ago. Since then, many thousands of volcanoes have built up across the surface. They’re not as dramatic as the volcanoes on Earth, though. They’re wide but generally not very tall, so their slopes are gentle.
Other prominent features also have a volcanic origin. Collapsed lava tubes form canyons, and molten rock pushing up from below created domes as wide as states but no taller than a good-sized hill.
Even with these features, about 80 percent of the surface of Venus is no more than one kilometer above or below the average elevation. The tallest mountain is taller than Mount Everest, but the lowest spot is only a bit more than a mile deep. That’s far shallower than the ocean trenches here on Earth — helping to give our planetary neighbor a smooth complexion.
Look for Venus shortly after sunset this evening, to the lower right of the crescent Moon. It’s brilliant but low in the sky, and sets by about the time the last blush of twilight fades away.
Script by Damond Benningfield