Years ago, planetary scientists thought of Venus as Earth’s sister planet. Similar in size, both close to the Sun, both rocky bodies, Earth and Venus were practically considered two of a kind.
That abruptly changed, however, when astronomers got their first close-up look at Venus. The moment arrived in 1962, when Mariner 2 flew by the planet, and far more forcefully in 1970, when Venera 7 touched down on the hellishly hot surface. Not only do surface temperatures on our sister planet exceed 750° F (400° C), but Venus’ thick carbon-dioxide atmosphere produces a greenhouse effect that hosts sulfur-dioxide and sulfuric-acid clouds. It’s not a friendly environment for living things of any sort.
Scientists’ understanding of Venus and its geology again catapulted forward with the most significant mission thus far: the Magellan spacecraft. Magellan mapped 98 percent of the planet’s surface and returned thousands of spectacular views of Venus’ geological features. Almost one-quarter of the images returned by Magellan became computerized, 3-D images of regions with altitude effects exaggerated by the image processors. For the first time, humans had a good look at what Venus is really like.
There were surprises. The most amazing was the relative lack of craters compared with other inner solar system bodies like the Moon, Mars, and Mercury. Water, wind, volcanoes, and tectonic shifts constantly resurface our planet. Venus must be hiding many old craters, too. Astronomers wondered what resurfacing forces could keep Venus’ surface looking so young.
In this week’s episode of Infinity & Beyond, host Abigail Bollenbach will guide you through Magellan’s evidence that suggests Venus got a face-lift in the relatively recent past.
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