A massive, bow-shaped wave was spotted for the first time in the highest regions of Venus’ atmosphere, perplexing astronomers.
The structure was captured by the Japan Aerospace Exploration Agency (JAXA) in some of the first images returned by their Akatsuki orbiter following a troubled orbital insertion
in late 2015. Using both infrared and UV imaging, researchers spotted the prominent feature in the planet’s upper atmosphere, where winds whip by in excess of 200 miles per hour. Any features spotted in the atmosphere should get carried along by the fierce winds, but this curved wave remained planted firmly in place, lasting for at least four days.
The wave extends for more than 6,000 miles, stretching nearly from pole to pole. It is marked by the presence of slightly warmer air in the upper portion of the planet’s thick atmosphere, some 40 miles above the surface. While small aberrations are common in the upper atmosphere, such a large feature, to say nothing of one that refuses to move, is highly uncommon.
Venus’ atmosphere is in a state of super-rotation, meaning it moves much faster than the planet does. Venus rotates very slowly on its axis, completing just one rotation every 243 Earth days — longer than it takes the planet to go around the sun. On Earth, winds move only 10 to 20 percent the speed of the planet at most, but on Venus they far outpace the planet’s stately spin.
The researchers believe that the enormous structure might be caused by so-called “gravity waves” in Venus’ atmosphere. Gravity waves (which are entirely different than gravitational waves
), are upheavals in a planet’s atmosphere caused by winds colliding with features on the surface. In the case of Venus, mountainous features on the surface may be forcing winds into the upper atmosphere, where they slow down enough to create a lasting bow wave. Indeed, the atmospheric bulge is located above Aphrodite Terra, a continent-sized region of highlands. The researchers discuss their findings in a paper published Monday in Nature Geoscience.