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September 2021

Current Events: Venus Lacks Plate Tectonics, But It Has Something Much More Quirky

By Stacy Palen

A reanalysis of Magellan images has led to the hypothesis that Venus has “campi,” or blocks of rock that float on the mantle, shimmying and bumping into each other like packs of ice.

Below are some questions to ask your students based on this article.

1). Describe plate tectonics on Earth.

Answer: On Earth, a small number of very large plates float on top of the mantle, bumping into each other, sliding under or along each other’s boundaries, and creating geological features.

2). Why is liquid water required for plate tectonics?

Answer: Water lubricates the plates, permitting them to break bend and flow.

3). What happened to Venus’ liquid water?

Answer: It was lost during some kind of apocalyptic event that heated Venus to temperatures too high for liquid water to persist. This event happened about a billion years ago.

4). How is the process with campi, described in the article, different from that of plate tectonics?

Answer: Campi don’t flow past, rise over, or slide under each other. The campi are much smaller than the tectonic plates on Earth.

5). What is the evidence that this process might still be ongoing?

Answer: The observed campi are in the lava-covered lowlands, which are geologically young.

6). How will scientists explore whether this process is still actually occurring?

Answer: Several spacecraft are heading to Venus over the next few years. These spacecraft have higher-resolution radars than Magellan's and will compare the current positions of the campi with the positions observed by Magellan.

Classroom Stories: Teaching Climate in Astronomy Class

By Stacy Palen

This year, in particular, feels like a year in which we might be able to move the needle a little bit on the public understanding of climate change. The effects are starting to capture the attention of ordinary citizens who are infinitely distracted by…everything. Between the fires in the West, the extreme heat, and Hurricane Ida, ordinary citizens are starting to wake up to the fact that climate change matters to them.

Climate change is a thread that runs through my astronomy class, with a day devoted to it during my discussion of planetary atmospheres, and a lengthy revisit to it in our astrobiology discussion. But I also mention it when we talk about telescopes and atmospheric opacity (if the IR light can’t get down to the ground, it can’t get out to space, either, which is interesting because it has consequences that we talk about later in class). And I mention it when I talk about molecular bonds. And I also talk about it when we talk about “going to Mars” and whether there are fossil fuels there. In fact, I mention it matter-of-factly every time I see a connection that even remotely makes sense.

I also happen to teach a more advanced course in which we discuss climate and energy issues in gory physical detail, which means that I’m always looking for simulations and interactive sites that I can build activities around for students to use as they develop an intuition for the scope and complexity of the problem. (These activities often don’t make it into my Norton textbooks because they use resources we don’t control, so I can’t rely on them to be available, or to work the same way, for more than a semester at a time.) 

Earlier this year, the Climate Reality Project pulled together six of these interactive tools, with explanations about each. I found the list useful, and it might be useful to you, too!

Additionally, I have used the En-ROADS climate simulator for years, and it keeps getting better and more powerful (although that also means more complicated). I have an activity where students work in groups to negotiate how to adjust the world economy to try to control climate change. Hilarity, and sometimes intense arguments, ensue. Sometimes, they mention that this is one of the most meaningful activities of the whole semester because it reveals how complex these issues are.

I have also used the Climate Time Machine, which makes it easy to run as a demonstration during lecture. You slide the slider to see, for example, the impact of sea-level rise on various geographic areas.

There’s also a very nice Footprint Calculator on the list. There are lots of these around, but this particular one runs by sliders and dials, which makes it simple to use in a classroom situation where you don’t want students to get stuck on the details of one particular issue. The calculator ends by answering two questions: a). “On what day of the year have you used up your share of resources?” and b). “How many Earths would we need if everyone lived like you?” This offers a really great framing of the subject that students intuitively understand. If the answer to a). is before December 31, and the answer to b). is more than one Earth, then we’re in big trouble.

Feel free to check out these interactives and let me know if you end up using any of them in the classroom! I’m always looking for new ideas to help make this issue more concrete for students, and I always hate to leave them feeling helpless and wondering, “Yes, but what can I do?” These interactives help them find a meaningful way forward.