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Moon and Venus
Thanks to satellites, you don’t have to see the ocean floor to know what it looks like. The surface of the ocean bulges upward over underwater mountains, and forms depressions above ocean basins. So measuring contours in the ocean surface can provide a rough look at what’s below.
And a satellite around Venus has showed that you don’t have to see that planet’s surface to know what it looks like.
A blanket of clouds hides the surface of Venus from view. A few spacecraft have used radar to peek through the clouds, allowing them to map the surface. But the last of these missions ended more than two decades ago.
A more recent mission found clues to the surface contours in the clouds. Venus Express orbited the planet for eight years. It found ripples in the clouds downwind of a mountain range known as Aphrodite Terra. It also found that the clouds in that region contained high concentrations of water vapor.
Scientists say those features are caused by winds at the surface flowing over the mountains. The winds create waves that ripple all the way to the top of the atmosphere. The rising air also carries water vapor. So looking at the clouds helps reveal what’s happening far below.
Venus stands in the west-southwest as darkness falls this evening. It’s quite low in the sky, but it’s the brilliant “evening star,” and it’s close to the left of the crescent Moon, so you shouldn’t have much trouble spotting it.
More about Venus and the Moon tomorrow.