Astro Blog

By Hannah Richter , Science.  Excerpt: In the late 2000s, planetary scientists scoured data gathered by NASA’s Cassini mission, a Saturn orbiter, about the planet’s mysterious icy moon Titan. Their exciting conclusion: The frozen world harbored an ocean sloshing around tens of kilometers beneath a thick ice shell. The ocean, hundreds of kilometers deep itself, might even be a cauldron for the “prebiotic” organic chemistry that led to life on Earth, they proposed. Now, nearly 2 decades later, researchers think they may have gotten the story all wrong. Research  presented today  here at the American Geophysical Union’s annual meeting and  published in  Nature  claims that although Titan may have once harbored a liquid ocean, today it is frozen, except for smaller melted zones deep beneath the surface. If true, the discovery will upend the long-standing assumption that Saturn’s biggest moon is a water world, like other moons in the outer Solar System,  in...

https://eos.org/articles/to-make-a-big-moon-start-with-a-small-planet By Kimberly M. S. Cartier , Eos/AGU.  Excerpt: In a contest of which planet in the solar system has the most relatively massive moon, Earth takes the prize. The Moon is roughly 1% of Earth’s mass, whereas the moons of all the remaining moon-bearing planets—that’s all of them save for Mercury and Venus—are less than one ten thousandth their planets’ masses. ...“We think that a giant impact is a very efficient way to form fractionally large moons,” said  Miki Nakajima , a planetary scientist at the University of Rochester in New York. Large collisions are thought to be a common occurrence in the chaos of a still-forming solar system, but if all giant impacts formed fractionally large moons, our solar system would be rife with them. ...Using computer simulations, Nakajima and her colleagues explored what happens when rocky or icy would-be planets of various sizes collide. The researchers found that after such a...

https://www.sciencemag.org/news/2020/11/famed-meteorite-reveals-early-water-mars-and-early-outer-space-bombardment Source:  By   Paul Voosen .  Excerpt: With just 15 grams of the 4.4-billion-year-old   “Black Beauty” meteorite   [from Mars] discovered in 2011 in the western Sahara, [Martin Bizzarro’s] team has revealed a record of asteroid impacts and volcanic eruptions spanning nearly all of martian history. One of the most surprising findings: After Mars underwent a pummeling early in its life, all went quiet—even during a time, nearly 4 billion years ago, when our Solar System was thought to have suffered a cataclysmic assault... .  

https://www.nasa.gov/image-feature/ames/planetary-impact-simulation s Source:    By Frank Tavares, NASA.  Excerpt: The histories of planets across our solar system and beyond are filled with collisions and transformations. New research is helping scientists understand how colossal impacts, like the one with Earth thought to have formed the Moon, are impacting the atmospheres of rocky planets.In the animation above, a Mars-like mass grazes an Earth-like mass, replicating the traditional theory for the impact that formed the Moon. Some atmosphere is lost, accompanied by a shockwave....    

https://www.nytimes.com/2020/07/25/science/mars-moons-phobos-deimos.html Source:   By Robin George Andrews, The New York Times.  Excerpt: our planetary neighbor is adorned with two moons: puny Phobos, a lumpy mass 17 miles across; and diminutive Deimos, just 9 miles long. Their names in ancient Greek may mean “fear” and “dread’, but the aesthetics of these Lilliputian space potatoes inspire anything but. ...the desire to visit Phobos and Deimos was galvanized by their deeply mysterious nature. “They’re super weird, confusing and interesting,” said Abigail Fraeman, a planetary scientist studying Mars, Phobos and Deimos at NASA’s Jet Propulsion Laboratory. ...they look like asteroids foreign to the red planet but behave like byproducts of Mars’ early, impact-laden history. And if that Japanese mission manages to grab some samples and decode the chemistry of the mangled moons, we might be able to discover their origins. In doing so, we won’t just gain a better understanding of ...

https://www.sciencemag.org/news/2019/04/japanese-spacecraft-may-have-just-blown-crater-distant-asteroid Source:   By Dennis Normile, Science Magazine. Excerpt: Japan’s Hayabusa2 mission continued its unprecedented explorations today by apparently creating an artificial crater in an asteroid, a space exploration first. Officials confirmed that the operation to fire a projectile into asteroid Ryugu went smoothly, though as of early evening Japan time they were still trying to confirm whether a crater had actually been formed. ...Developed by the Japan Aerospace Exploration Agency’s Institute of Space and Astronautical Science in Sagamihara, Hayabusa2 was launched in December 2014 and traveled 3.2 billion kilometers through space before reaching its home position 20 kilometers away from Ryugu, a diamond-shaped asteroid about 1 kilometer by 900 meters in size orbiting between Earth and Mars. The mission’s objective is to collect samples both from Ryugu’s surface and its interior an...

https://www.sciencemag.org/news/2019/01/how-ancient-cataclysm-may-have-jump-started-life-earth Source:   By Robert F. Service, Science Magazine Excerpt: ATLANTA—A cataclysm may have jump-started life on Earth. A new scenario suggests that some 4.47 billion years ago—a mere 60 million years after Earth took shape and 40 million years after the moon formed—a moon-size object sideswiped Earth and exploded into an orbiting cloud of molten iron and other debris. The metallic hailstorm that ensued likely lasted years, if not centuries, ripping oxygen atoms from water molecules and leaving hydrogen behind. The oxygens were then free to link with iron, creating vast rust-colored deposits of iron oxide across our planet's surface. The hydrogen formed a dense atmosphere that likely lasted 200 million years as it ever so slowly dissipated into space. After things cooled down, simple organic molecules began to form under the blanket of hydrogen. Those molecules, some scientists think, even...

https://apnews.com/5604f183641342f1ad7f99f2ce665181 Source:   By Emiliano Rodriguez Mega, Associated Press. Excerpt: Astronomers are still finding moons at Jupiter, 400 years after Galileo used his spyglass to spot the first ones. The latest discovery of a dozen small moons brings the total to 79, the most of any planet in our solar system. Scientists were looking for objects on the fringes of the solar system last year when they pointed their telescopes close to Jupiter’s backyard, according to Scott Sheppard of the Carnegie Institute for Science in Washington. They saw a new group of objects moving around the giant gas planet but didn’t know whether they were moons or asteroids passing near Jupiter. ...The team is calling one of the new moons an ‘oddball’ because of its unusual orbit. Sheppard’s girlfriend came up with a name for it: Valetudo, the great-granddaughter of the Roman god Jupiter. Valetudo is in Jupiter’s distant, outer swarm of moons that circles in the opposite ...

http://www.sciencemag.org/news/2018/05/asteroid-came-another-solar-system-and-it-s-here-stay Source:   By Daniel Clery, Science Magazine. Excerpt: While astronomers around the world had their eyes fixed last year on ‘Oumuamua, a lump of rock from another planetary system that whizzed through ours, little did they know that another interstellar interloper was quietly living among us. And this one appears to have been here for billions of years. Astronomers first spotted the object, an asteroid called 2015 BZ509 that is orbiting close to Jupiter, in 2014. They knew it was unusual because it was traveling around the solar system in the opposite direction as almost everything else. ...Astronomers have found other objects in “retrograde” orbits, perhaps knocked off course by passing too close to a giant planet, but 2015 BZ509’s orbit was the weirdest of all because it is also elongated and out of alignment with the planets and other bodies. To find out why, a pair of astronomers ran...

https://eos.org/articles/scientists-discover-stromboli-like-eruption-on-volcanic Source:    By JoAnna Wendel, Eos/AGU By JoAnna Wendel, Eos/AGU. For GSS Energy Flow chapter 2. Excerpt: Jupiter’s moon Io is known for its lava fountains and roiling lava lakes, but scientists had never seen such an intense eruption in their data until now. ...But wait, you ask, didn’t Galileo plunge into Jupiter’s atmosphere at the end of its mission, way back in 2003? Well, yes. But the orbiter, at that point, had collected so much data about the Jovian system and its Galilean moons (Ganymede, Io, Callisto, and Europa) that scientists still haven’t waded through it all, even 14 years later. ...Io’s surface is constantly gushing lava—every million years or so, the entire moon’s surface completely regenerates. From towering lava fountains that can reach 400 kilometers high to violently bubbling lava lakes that burst through freshly cooled crust, these oozing lava fields can stretch many thous...

Source:   By CBC News, Thomson Reuters Excerpt: A NASA spacecraft has detected carbon-based materials, similar to what may have been the building blocks for life on Earth, on the Texas-sized dwarf planet Ceres that orbits between Mars and Jupiter in the main asteroid belt, scientists said on Thursday. The finding puts Ceres, a rock-and-ice world about 950 kilometres in diameter, on a growing list of places in the solar system of interest to scientists looking for life beyond Earth. The list includes Mars and several ocean-bearing moons of Jupiter and Saturn. The discovery, published in the journal Science, was made by a team of researchers using NASA's Dawn spacecraft, which has been orbiting Ceres for nearly two years. "I think these organic molecules are a long way from microbial life," Dawn lead scientist Christopher Russell of the University of California Los Angeles (UCLA) wrote in an email to Reuters. "However, this discovery tells us that we n...

Source:   By Kenneth Chang, The New York Times Excerpt: ...one might think that meteorites that fall on Earth ought to be just like the asteroids that pass through Earth’s neighborhood. “That’s what everybody would have expected,” said Philipp R. Heck, the curator in charge for the meteorite and physical geology collections at the Field Museum of Natural History in Chicago. Planetary scientists were surprised almost a decade ago when they discovered that the most plentiful types of meteorites they had collected and studied on Earth were actually not common in space. In a paper published Monday by the journal Nature Astronomy, an international team of researchers led by Dr. Heck says it has uncovered part of the explanation. Mineralogical evidence in some meteorites had already pointed to a cataclysmic collision in the asteroid belt about 466 million years ago — long before dinosaurs, when multicellular animals were still fairly new. (Dr. Heck estimated that any skywatchers back...

Source:   By Raluca Rufu, Oded Aharonson, & Hagai B. Perets, published in Nature Abstract: The hypothesis of lunar origin by a single giant impact can explain some aspects of the Earth–Moon system. However, it is difficult to reconcile giant-impact models with the compositional similarity of the Earth and Moon without violating angular momentum constraints. Furthermore, successful giant-impact scenarios require very specific conditions such that they have a low probability of occurring. Here we present numerical simulations suggesting that the Moon could instead be the product of a succession of a variety of smaller collisions. In this scenario, each collision forms a debris disk around the proto-Earth that then accretes to form a moonlet. The moonlets tidally advance outward, and may coalesce to form the Moon. We find that sub-lunar moonlets are a common result of impacts expected onto the proto-Earth in the early Solar System and find that the planetary rotati...

Source:   By Sid Perkins, Science Excerpt: Miniplanets zooming through our early solar system passed close to our moon and tugged it into the strange, tilted orbit it has today, according to a new study. The findings solve a longstanding mystery and may also explain why Earth’s crust is unexpectedly rich in gold and platinum: When some of these small planets slammed into Earth, they delivered a payload of precious metals. Scientists have long debated the origin of the moon. The prevailing idea, first proposed decades ago, is that a Mars-sized planet collided with Earth, flinging material into space that then coalesced into our only natural satellite. According to current models of that collision, the ring of debris that eventually became the moon should have ended up in a plane tilted no more than 1° from the ecliptic, the plane in which Earth orbits the sun, says Kaveh Pahlevan, a planetary scientist at Université Côte d’Azur in Nice, France. But in fact, the moon’s orbital in...

Source:   NASA RELEASE 15-032. Excerpt: NASA scientists have determined that a primitive ocean on Mars held more water than Earth's Arctic Ocean and that the Red Planet has lost 87 percent of that water to space.... Scientists have been searching for answers to why this vast water supply left the surface. Details of the observations and computations appear in Thursday’s edition of Science magazine.... “With Mars losing that much water, the planet was very likely wet for a longer period of time than was previously thought, suggesting it might have been habitable for longer,” said Michael Mumma, a senior scientist at Goddard and the second author on the paper. See also New York Times article Ancient Mars Had an Ocean, Scientists Say . http://www.nasa.gov/press/2015/march/nasa-research-suggests-mars-once-had-more-water-than-earth-s-arctic-ocean/

Source:   Nancy Atkinson, Universe Today Excerpt: The formation of Saturn’s rings has been one of the classical if not eternal questions in astronomy. ... The two leading theories involve a small moon that was shattered by meteor impacts, or the tidal disruption of a comet coming too close to Saturn.  ...But one researcher has provided a provocative new theory to answer that question. Robin Canup from the Southwest Research Institute has uncovered evidence that the rings came from a large, Titan-sized moon that was destroyed as it spiraled into a young Saturn.... www.universetoday.com/75071/saturns-rings-formed-from-large-moons-destruction/