An undersea volcano erupts! Plus asteroids, moons, and heavy elements

This is an astronomy newsletter, so I gotta cover a lot of ground. And ocean. And sky.

May 6, 2024 Issue #717

Shameless Self-Promotion

Where I’ll be doing things you can watch and listen to or read about

My friends at the kids’ podcast Brains On interviewed me for their episode about living on the Moon!

Brains On is a terrific and award-winning podcast for science-curious people that’s a lot of fun and covers a wide range of science topics. If you or someone you know has kids then let them know about it! They’ll love it.

Speaking of being interviewed about the Moon for a kids’ show, I talked with the folks at The Children’s Hour about how the Moon formed (along with lots of other scientists who study our natural satellite)! This show is another great one for kids, so again, spread the word!

Pic o’ the Letter

A cool or lovely or mind-bending astronomical image/video with a description so you can grok it

Not all volcanoes erupt on land. Some like to keep things under the surface. Of the ocean, at least.

Kavachi is an active volcano off the coast of Papua New Guinea, near the islands of Vangunu and Nggatokae. It’s just barely submarine, though, with its summit just 20 meters below sea level. Close! But not quite enough, yet, to breech the water’s surface.

But it’s close enough that the plume from a recent eruption could be caught by the hardworking Landsat 8 Earth-observing satellite, which traced the arcing plume for about 20 kilometers:

Blue ocean dominates the image, with an arcing greenish-teal plume seen from the volcano.

The Kavachi volcanic plume is completely underwater, but easily visible in this Landsat image. Credit: NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey

Coooool. Ocean currents blow the plume to the northeast. You can see some clouds and even waves on the ocean in this shot. The plume itself is of course very hot when it leaves the volcano, and contains rock, iron, and other elements from deep underground.

This wider shot shows it in context:

Blue ocean and white clouds, with the volcano plume at the bottom, and dark grren islands near the top.

A wider view of the plume. Credit: NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey

I found this image on the ever-wonderful Earth Observatory Image of the Day, and this is one you should bookmark. I check it every day, and I’m always delighted to see imagery of our wonderful planet from space.

News Roundup

Who can keep up with everything these days?

  • Back in 2022, on The Old Site, I wrote about a new way to discover asteroids in huge images of the sky. You can go to that link to see how it works, but at the time I said it has great promise for finding lots of new (to us) space rocks. And that promise is starting to become realized! My friends at The B612 Foundation just announced they used the method to find—get this27,500 new asteroids! Most are in the main belt between Mars and Jupiter, but 100 of them are near-Earth asteroids, which can get closer to Earth. They used over 5 billion separate observations of the sky from various astronomical surveys to look for these asteroids, which is a daunting task. It’s amazing this can be done, and a boon to those of us who are concerned that one day one of these rocks will hit us. The first step is finding them, and this is a huge stride. Bonus: The method is called Tracklet-less Heliocentric Orbit Recovery, or THOR. 

    A graph showing how many asteroids are discovered yearly, broken up by quarter. Q1 of 2024, in which this technique was used, is far higher than any previous quarter.

    Asteroids discovered by quarter, measured in the thousands. The new technique blows away the previous quarters. Credit: The Asteroid Institute

  • In BAN 676 I wrote about an asteroid that orbits the Sun on a path that is very similar to that of Earth, enough that it acts a bit like a quasimoon. As I wrote then, the asteroid, 469219 Kamo’oalewa, is a few dozen meters across and bears some similarity in composition to the Moon. Astronomers are wondering if an asteroid impact on our actual satellite could have flung out something this size, and new results indicate that yes, it could, and they may have actually located the impact point: Giordano Bruno, a 22-km-wide crater on the Moon’s far side. They show [link to journal paper] that a decent sized lunar impact could launch a rock into solar orbit, and the age of Giordano Bruno (roughly 1 – 10 million years) is about right to be Kamo’oalewa’s origin. It’s not a smoking gun — well, figuratively, maybe, but not literally, or, in this case, metaphorically — but it’s certainly intriguing. Tianwen-2, a Chinese space mission planned for launch in 2025 is set to return a sample from the asteroid, so we may found out about all this pretty soon.

  • How heavy an element can nature make? We know that elements up to uranium can be made in supernova explosions, but most atoms in the periodic table with more mass in their nuclei have been made by humans. An interesting bit of work just published posits that some stars made much, much heavier elements, though [link to research paper]. “R-process” elements are created when atoms are in a neutron-rich environment (like the cores of massive stars as they explode) and help them build up their nucleus. These include strontium, platinum, and more. By looking at the elemental composition of a few dozen stars, the astronomers deduce that some of the r-process elements in them may actually be due to nuclear decay of far heavier elements, with atomic masses greater than 260 — higher than any naturally occurring element known, and higher than many of the human-made ones, too.

Et alia

You can email me at [email protected] (though replies can take a while), and all my social media outlets are gathered together at Also, if you don’t already, please subscribe to this newsletter! And feel free to tell a friend or nine, too. Thanks!


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