(Intro)

Hank: Venus is a strange, extreme sort of planet for lots of reasons.  For one thing, it rotates so slowly that its day is longer than its year.  Combine that with its chokingly thick atmosphere and you end up with one of the least windy surfaces in the solar system.  Fly up high, though, and you'll find the clouds rushing by at a blistering 360km/hr.  That's why astronomers with Japan's Akatsuki's spacecraft were so shocked to find a giant stationary feature in Venus's cloud tops.  

This new finding was the result of some of the first observations by Akatsuki and was announced this week in the journal Nature Geoscience.  The authors described what they saw as an enormous bow structure, like the shape created by a boat cutting through the water.  It spanned 10,000 kms of Venus' sky, distorting an entire hemisphere's worth of clouds and an altitude of 65kms and seemed hotter than the surrounding atmosphere.  

If it moved like a normal cloud, this thing should have been circling Venus pretty quickly.  Instead, four days later, it had hardly budged and when Akatsuki was able to observe the area again, about a month later, it was gone.  Now, when the researchers plotted this structure's position on a map of Venus' surface, they found it sittin' smack dab in the center of a mountainous region called Aphrodite Terra.  This led them to conclude that Akatsuki had spotted a huge example of a feature that's common here on Earth: what's known as a gravity wave.  

These kinds of waves happen when buoyancy pushes up a fluid, like air or water, and gravity pulls it back down.  Gravity waves are not the same thing as gravitational waves, the ripples in space-time caused by things like merging black holes.  The most common gravity waves on Earth are the ones that surfers ride on, but they can also  form in the atmosphere, often when air rushes over the top of a mountain.  

The feature is seen on Venus just downwind of a big peak, so it's probably created by rushing air over that peak.  Even though it's common for waves like these to stay in one place, when they reach such a massive scale, they usually move at the speed of the surrounding wind.  Now that's clearly not the case here, and the researchers don't know why the wave stayed still or why it later disappeared.  They also aren't sure of how waves like this could end up so high in Venus' atmosphere, when simulations show that if it can reach a height of 10kms, getting the rest of the way would be a lot easier, and if the surface winds on Venus turn out to be more dynamic than we thought in the past, they could create waves that high.  

Akatsuki is slated to operate well into 2018, so with more observations, hopefully we'll learn exactly how this giant wave came to exist and where it went.  

Now, this was also a big week for space flight.  Just four months after an explosion on the pad claimed a rocket and its payload, SpaceX was back in action with a satellite launch last Saturday.  The launch came less than two weeks after the conclusion of the accident investigation.  The report, a joint effort between SpaceX and federal agencies, determined that the company's Falcon 9 exploded after the failure of an internal tank.  This small tank, called the Composite Overwrapped Pressure Vessel holds the helium needed to pressurize the rocket's liquid oxygen fuel.  Buckles in the wall of the tank formed gaps that allowed super cold oxygen to pool in the area where friction could ignite it, causing the explosion.

By returning to an older tank fueling process, SpaceX got permission to resume their flight schedule.  Onboard the Falcon 9 were 10 satellites for communications company Iridium, the first of at least 70 that SpaceX is set to launch.  The rocket's first stage also made a picture perfect touchdown on a floating platform in the Pacific ocean, the first such landing off the West coast, and that's just the start of the company's plans for this year.

They're still catching up after September's accident and they're also planning the inaugural flight of the much larger Falcon Heavy rocket, which is capable of launching more than 54 metric tons to low-Earth orbit.  They're also hoping to launch one of their previously landed rockets for the first time.  If all goes well, these used rockets could dramatically cut the cost of sending space into space, and then there's the contract with NASA to launch astronauts to the International Space Station.  Test flights of the human-ready Dragon capsule could begin late this year, with a 2018 goal for the first crew mission.

I don't know about you, but I am excited and a little nervous to see how that goes.  If you wanna learn more about these kinds of discoveries or missions as they happen, head to YouTube.com/SciShowSpace, subscribe, we will be bringing you all kinds of great content.  We make two episodes a week and we like it when you watch them.  If you wanna support the show, if you wanna help us make stuff like this, that would also be great.  You can do that at patreon.com/scishow.