Changing Worlds: Weather, Quakes, & Impacts

By on October 22, 2019 in

(Things may look a bit different this week; Susie is on a much-deserved vacation and Pamela is filling in.)

One of the things that makes planetary science so interesting is the regular changes we see in other worlds and our own. In this show, we look at weather on Saturn, a historic landing on Venus, and our own Earth’s impacts and quakes.

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Here on Earth, we’re experiencing southern hemisphere spring and northern hemisphere fall as our planet changes its orientation with the Sun. Our world’s weather is driven by the changing fall of Sunlight on our tilted planet. Our world isn’t the only one to have seasonal weather patterns, and now, Earth-based planetary scientists have revealed a new kind of storm on the tilted planet Saturn. In 2018, observers using a combination of ground and space-based telescopes observed Saturn’s North polar region and saw mid-sized storms that were unlike anything previously observed. 

credit A. SÁNCHEZ-LAVEGA ET AL/NATURE ASTRONOMY 2019

While Saturn is often a nothing more than a beige ball of gas, storms are known to expand up from lower layers in the atmosphere, bringing white water vapour to the surface. These massive storms typically appear about every 2 Saturnian years, or every 60 earth years. We’ve also observed a number of smaller storms over the years that appear as small white spots.

These storms, however, are larger than the small white spots, and smaller than the great storms, and nothing like this has been previously observed. Exactly what caused this mid-sized storm is a bit of a mystery. One idea is that an earlier great storm, just 2 years ago, consumed so much energy from the atmosphere that enough energy wasn’t available for this storm to balloon up, but that story doesn’t match past observed behaviour, and also would require storms at different latitudes to somehow draw energy from the same energy reservoir, and this just isn’t thought to be a thing. This has led some to postulate this is an entirely new kind of storm that just hasn’t been observed before.

The reality is, we haven’t been observing worlds up close and personal for very long. Today, Oct 22, marks the 44th anniversary of the landing of the Venera 9 probe on the surface of Venus. While Venus is one of the most violent worlds in our Solar System, it was also the first non-Earth planet that we ever landed on. This mission included both a landed and an orbiter that worked until Christmas 1975. During its parachute enabled descent, the Venera lander measured the composition of the atmospheric, telling us about the many acids of Venus, and determined that the thick cloud cover lasts to about 30km above Venus’s surface. On landing, this image of a very rocky surface was acquired. While it was the first to be explored, Venus has not been among any of the last few worlds we’ve gone to, and it is my hope that we are able to send more missions in the coming years.

credit Ted Stryk from Venera 9 Data

From Saturn and Venus, we now return to our own planet Earth. While they are often hard to see, our world is actually scared with massive impact craters in a myriad of places. One of these ancient rings is in the middle of modern Sweden, and appears as a ring of lakes in the midst of vegetation. This 400 million year old feature is called the Siljan Ring, and recently, mining teams taking core samples to look for natural gas, found microbial activity instead. Rock cores studies at the Linnaeus University revealed evidence of long-term deep microbial activity that appears to have arisen in the impact region and then lasted for 300 million years. These microbes weren’t the oxygen breathers we’re used to, but were instead methanagins and also microbes that process sulphate into sulphide. While it doesn’t appear that the life originated from the asteroid strike, it seems that the conditions created by the impact produced a good place for life to thrive. This creates an paradigm of impact sites being optimal places for life, and gives us a new and interesting way to consider the formation and nurturing of life on other worlds.

NASA WorldWind/Vesta/Landsat 7

This is also a reminder that our world is undergoing constant change. From the punctuating impact of asteroids, to the restless motion of plate tectonics, our world is still very much alive. For some, this should be evidence of a clear and present danger, and by for some, I mean you California. Last July, a pair of Earthquakes over the 4th of July holiday shook the Los Angeles Basin as the Ridgecrest Fault shifted. While these Earthquakes and their related preshocks and aftershocks released energy from that particular fault line, it’s unclear how that release of energy may have affected surrounding fault lines. One of these faults, the Garlock fault, had previously been dormant, but now appears to be on the move, with the two sides of fault creeping along. This kind of slow and gradual release of energy through steady motion is a best case scenario for this fault line, which is capable of generating a magnitude 8 quake. The question is, will this fault line, which spans from the Ridgecrest fault to the San Andres and fault trigger the proper noun’ed Big One that so many seismologists predict. This is a hard one to answer. On one hand, the San Andres fault is predicted to release at any moment, and if something is already likely to go off at any moment, can you say that something increases the likelihood that it will do what it is already predicted to do? On the other hand, by talking about these fault lines, and pointing out that the energy in the faults is literally rearranging California’s land… well, maybe this will help get people to realise, Earthquake preparedness is a must. Everyone should have emergency kits in both their home and their cars, and be ready when the worst finally comes. Again, this not an if, this is a when. There are lots of resources available to help you figure out what you need.

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