New Looks At Old Moons

europa-with-plumesI reading where they’ve finally detected evidence of water plumes on Europa, an ice-crusted moon of Jupiter. (Image credit: NASA, ESA, and W. Sparks (STScI)) Video here. Very cool, and not just because of a surface temp of minus-260 F.

Since 1979, moons of the outer solar system have provided the most surprises to scientists directing probes launched from Earth. Voyager 1 flew by Jupiter at the end of the seventies, and Io, orbiting interior to Europa, intrigued fron the start. Scientists had seen nothing like it before: yellow with patches of white, orange, red, brown, and black. No craters. It was described as pizza, but it didn’t look very appetizing to me, except as food for the mind.

ioThe day after the probe’s encounter, scientist Linda Morabito, while processing images, noticed a significant irregularity. A bulge appeared on the Io horizon. Was it another moon, or a distant galaxy, or a computer error on the spacecraft? Very soon the bulge was assessed as a plume of gas erupting from what was earlier imaged as a black patch on the moon’s surface. This was the first time active volcanoes were detected on another world. (Mariner 9 found massive volcanoes on Mars in 1971, but these are long-dormant. We think.)

Dr Morabito recounts her discovery in this paper. It’s a thirty-page read, but excellent. The scientist details how good science is done. Featured: personal and professional collaboration, the sifting of ideas, and how good scientists are slow to jump to conclusions when confronted with new information that upsets the status quo.

io-videoCheck the five image sequence of volcanic activity from another probe, New Horizons, left. (Image credit.)

We know now that erupting moons are not unique in our solar system. Orbiting Saturn, Enceladus erupts water. That was a surprise. Pre-2006, the thinking went, a small moon the size of the British Isles isn’t substantial enough to exhibit such activity. But it does. There’s a lake of liquid water underneath the Enceladian crust.

Voyager 2 saw nitrogen geysers on Neptune’s main satellite, Triton. Are these the only instances? I would look to the moons of Uranus, if I were asked for the location of the next likely discovery.

And now we have evidence (but not proof) of water erupting from another solar system moon. Note that in the linked video on the Europa discovery that scientists have utilized two methods of observation. They imaged the moon tracking across the planet Jupiter as seen from Earth. They also looked at ultraviolet wavelengths to detect a tell-tale sign of water. (Think of water appearing not in the color of blue, but of “ultraviolet” in space.) These alone are not enough to confirm a discovery, not for careful scientists.

If I were teaching high school, this sequence of exploration and discovery would be an excellent example of planetary astronomy and scientific method, blended with one story of how real human beings interact with the universe. Read the papers, look at the images, and allow young students to posit their own views of what is out there. Hardly as exotic or scary as aliens with colored skins, but part of a real experience of wonder.

We look up. Or out. And we wonder. We observe what transpires in the universe around us. We draw upon existing knowledge, and we allow our thinking to expand. As an artist, I would hope we also allow for the expansion of our hearts. As a man of faith, I would pray this inspires an expansion of the spirit. God draws us more deeply to the Divine as we get more and more glimpses into the wonders of creation. And with the Psalmist, we can sing:

When I look at your heavens, the work of your fingers,
the moon and the stars that you have established;
what are human beings that you are mindful of them,
mortals that you care for them? (8:3-4, NRSV)


About catholicsensibility

Todd lives in the Pacific Northwest, serving a Catholic parish as a lay minister.
This entry was posted in Astronomy, Satellite Imagination, Scripture. Bookmark the permalink.

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