How long is a day on Venus? Scientists crack mysteries of our closest neighbor

[Jim__]

From phys.org

Venus is an enigma. It's the planet next door and yet reveals little about itself. An opaque blanket of clouds smothers a harsh landscape pelted by acid rain and baked at temperatures that can liquify lead.

Now, new observations from the safety of Earth are lifting the veil on some of Venus' most basic properties. By repeatedly bouncing radar off the planet's surface over the last 15 years, a UCLA-led team has pinned down the precise length of a day on Venus, the tilt of its axis and the size of its core. The findings are published today in the journal Nature Astronomy.

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The new radar measurements show that an average day on Venus lasts 243.0226 Earth days—roughly two-thirds of an Earth year. What's more, the rotation rate of Venus is always changing: A value measured at one time will be a bit larger or smaller than a previous value. The team estimated the length of a day from each of the individual measurements, and they observed differences of at least 20 minutes.

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Venus' heavy atmosphere is likely to blame for the variation. As it sloshes around the planet, it exchanges a lot of momentum with the solid ground, speeding up and slowing down its rotation. This happens on Earth too, but the exchange adds or subtracts just one millisecond from each day. The effect is much more dramatic on Venus because the atmosphere is roughly 93 times as massive as Earth's, and so it has a lot more momentum to trade.

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[multigraincracker]

1. Thanks for the information.

I've had a few of those days.

[lastlib]

2. They usually come when I don't get enough coffee............

(when do I *EVER* get enough coffee??!?)