This has to be my favorite photo I captured during the August 21 solar eclipse from Charleston, SC. It shows a phenomenon called Baily’s Beads, which is caused by the last bits of Sun peeking through low points and between mountains along the limb of the Moon in the final moments before 100% totality. They’re only visible for a few seconds between the “diamond ring” effect (which I did not capture) and the appearance of the Sun’s outer corona, and I’m very happy to have caught them on camera!
From a “mere” 93 million miles away we’re able to view the surface of our home star the Sun very well with telescopes on Earth and in space…you can even observe large sunspots with your unaided eye (with proper protection, of course.) But the surface details of other stars tens, hundreds, or thousands of light-years away can’t be so easily resolved from Earth. The details are just too fine and get lost in the brilliance of the stars themselves.
But astronomers have now produced the best image yet of the surface of another star beyond our Solar System. Using the European Southern Observatory’s Very Large Telescope Interferometer, located on a high plateau in Chile’s Atacama Desert where the sky is some of the clearest and driest in the world, a team of scientists have mapped the movement of material in the atmosphere of Antares, a red supergiant star 700 times the size of our Sun that shines brightly in the heart of the constellation Scorpius. The observations enabled them to determine how material moves through Antares’ atmosphere and then construct an image of the star itself—the most accurate representation of another star besides the Sun.
There are a lot of moons in our solar system—175 major planet satellites, and three times that if you count every natural satellite of every known object (like asteroids)—but among them our own capital-M Moon is in many ways unique. At a full quarter the size of Earth, only Pluto has a moon so near in size to itself, and unlike the swarms of icy worlds orbiting the gas giants the Moon is oddly very similar in composition to Earth…so similar, in fact, that it’s been casting increased doubt on the accuracy of the best-accepted model of the Moon’s formation, namely the Giant Impact Hypothesis.
Suggested in 1975 by planetary scientists William K. Hartmann and Don Davis, the model claims that the Moon was created 4.5 billion years ago when a Mars-sized world that’s been named Theia impacted the newly-formed Earth, blasting a chunk of molten material out into orbit that solidified to form the Moon. The model is based on a lot of science and answers a lot of questions, but not all—including a key issue of why the Moon today appears compositionally identical to Earth and not a mixture of Earth and a completely different planet.
As advanced computer measurement and modeling capabilities have increased a new wave of researchers are tackling the conundrum of the Moon’s origins, and a few new scenarios are coming to light. While ancient impacts are still involved, the question is now how many? With what kind of world(s)? And what exactly happened after the event?
“In the past five years, a bombardment of studies has exposed a problem: The canonical giant-impact hypothesis rests on assumptions that do not match the evidence. If Theia hit Earth and later formed the moon, the moon should be made of Theia-type material. But the moon does not look like Theia—or like Mars, for that matter. Down to its atoms, it looks almost exactly like Earth.”
Read the full story by Rebecca Boyle in The Atlantic here: The Moon’s Origin Story Is in Crisis
Saturn’s largest moon Titan is often called an analogy to early Earth, with its thick, chemical-rich atmosphere and widespread system of flowing rivers and north polar lakes. But located almost a billion miles away from the Sun, everything on Titan is shifted into a completely different—and frigid—level of existence from that found on Earth. With surface temperatures of 300 degrees below zero F, the lakes are filled with liquid methane and what’s life-giving water here is literally solid rock there. Even the rain on Titan falls as oversized drops of ethane.
But even in this extreme cryo-environment it’s possible that life may right now exist…life relying on an entirely different chemistry than what’s possible on our planet.
Recently scientists have identified a molecule on Titan called vinyl cyanide, or acrylonitrile. To Earthly life acrylonitrile is toxic and carcinogenic; luckily for us it isn’t naturally-occurring here. But on Titan it is and apparently in quantity; it’s possible that vinyl cyanide, raining down from Titan’s atmosphere into its vast hydrocarbon lakes, could even help form methane-based cell structures in much the same way phospholipids do here.
The molecule (C2H3CN) has the ability to form membranes and, if found in liquid pools of hydrocarbons on Titan’s surface, it could form a kind of lipid-based cell membrane analog of living organisms on Earth. In other words, this molecule could stew in primordial pools of hydrocarbons and arrange itself in such a way to create a “protocell” that is “stable and flexible in liquid methane,” said Jonathan Lunine (Cornell University) who, in 2015, was a member of the team who modeled vinyl cyanide and found that it might form cell membranes.
Further evidence of life “not as we know it?” Read more on Ian O’Neill’s Astroengine blog here: Vinyl Cyanide Confirmed: Weird Form of Alien Life May Be Possible on Saturn’s Moon Titan and in a Gizmodo article by Maddie Stone here: Potential Building Block of Alien Life Spotted in Titan’s Atmosphere
It’s been known for a while (especially since the 2009 LCROSS impact experiment) that there is water on the Moon. But so far the largest volume has been found as ice inside the shadowed walls of craters on the Moon’s south pole, likely originating from ancient comet impacts. Now, using data collected by India’s Chandrayaan-1 lunar satellite, researchers from Brown University in Providence, Rhode Island have identified water inside ancient pyroclastic flows located across the Moon’s surface—water that must have come from inside the Moon itself.
“We observe the water in deposits that are at the surface today, but these deposits are the result of magma that originally comes from deep within the lunar interior,” said Ralph Milliken, a geologist at Brown and lead author of the study. “Therefore, because the products of the magma have water, the deep interior of the Moon must also contain water.”
While the age and origin of this indigenous interior water aren’t yet known, its availability near the surface would be a valuable asset for any future human settlements on the Moon.
Read the rest of this article by Samantha Mathewson on Space.com here: The Moon’s Interior Could Contain Lots of Water, Study Shows