Latest news with #meteorites
Yahoo
25-06-2025
- Science
- Yahoo
The mystery of Mercury's missing meteorites – and how we may have finally found some
Most meteorites that have reached Earth come from the asteroid belt between Mars and Jupiter. But we have 1,000 or so meteorites that come from the Moon and Mars. This is probably a result of asteroids hitting their surfaces and ejecting material towards our planet. It should also be physically possible for such debris to reach the Earth from Mercury, another nearby rocky body. But so far, none have been confirmed to come from there – presenting a longstanding mystery. A new study my colleagues and I conducted has discovered two meteorites that could have a Mercurian origin. If confirmed, they would offer a rare window into Mercury's formation and evolution, potentially reshaping our understanding of the planet nearest the Sun. Because Mercury is so close to the Sun, any space mission to retrieve a sample from there would be complex and costly. A naturally delivered fragment, therefore, may be the only practical way to study its surface directly – making such a discovery scientifically invaluable. Get your news from actual experts, straight to your inbox. Sign up to our daily newsletter to receive all The Conversation UK's latest coverage of news and research, from politics and business to the arts and sciences. Observations from Nasa's Messenger mission have inferred the surface composition of Mercury. This suggests the presence of minerals known as such as sodium-rich plagioclase (such as albite), iron-poor pyroxene (for example enstatite), iron-poor olivine (such as forsterite) and sulfide minerals such as oldhamite. The meteorite Northwest Africa (NWA) 7325 was initially proposed as a possible fragment of Mercury. However, its mineralogy includes chromium-rich pyroxene containing approximately 1% iron. This poorly matches Mercury's estimated surface composition. As a result of this, and other factors, this link has been challenged. Aubrite meteorites have also been proposed as potential Mercurian fragments. Recent modelling of their formation suggests an origin from a large planetary body approximately 5,000km in diameter (similar to Mercury), potentially supporting this hypothesis. Although aubrites do not exhibit chemical or spectral (the study of how light is broken up by wavelength) similarities with Mercury's surface, it has been hypothesised that they may derive from the planet's shallow mantle (the layer beneath the surface). Despite ongoing research, the existence of a definitive meteorite from Mercury remains unproven. Our latest study investigated the properties of two unusual meteorites, Ksar Ghilane 022 and Northwest Africa 15915. We found that the two samples appear to be related, probably originating from the same parent body. Their mineralogy and surface composition also exhibit intriguing similarities to Mercury's crust. So this has prompted us to speculate about a possible Mercurian origin. Both meteorites contain olivine and pyroxene, minor albitic plagioclase and oldhamite. Such features are consistent with predictions for Mercury's surface composition. Additionally, their oxygen compositions match those of aubrites. These shared characteristics make the samples compelling candidates for being Mercurian material. However, notable differences exist. Both meteorites contain only trace amounts of plagioclase, in contrast to Mercury's surface, which is estimated to contain over 37%. Furthermore, our study suggests that the age of the samples is about 4,528 million years old. This is significantly older than Mercury's oldest recognised surface units, which are predicted (based on crater counting) to be approximately 4,000 million years. If these meteorites do originate from Mercury, they may represent early material that is no longer preserved in the planet's current surface geology. To link any meteorite to a specific asteroid type, moon or planet is extremely challenging. For example, laboratory analysis of Apollo samples allowed meteorites found in desert collection expeditions to be matched with the lunar materials. Martian meteorites have been identified through similarities between the composition of gases trapped in the meteorites with measurements of the martian atmosphere by spacecraft. Until we visit Mercury and bring back material, it will be extremely difficult to assess a meteorite-planet link. The BepiColombo space mission, by the European and Japanese space agencies, is now in orbit around Mercury and is about to send back high-resolution data. This may help us determine the ultimate origin body for Ksar Ghilane 022 and Northwest Africa 15915. If meteorites from Mercury were discovered, they could help resolve a variety of long-standing scientific questions. For example, they could reveal the age and evolution of Mercury's crust, its mineralogical and geochemical composition and the nature of its gases. The origin of these samples is likely to remain a subject of continuing debate within the scientific community. Several presentations have already been scheduled for the upcoming Meteoritical Society Meeting 2025 in Australia. We look forward to future discussions that will further explore and refine our understanding of their potential origin. For now, all we can do is make educated guesses. What do you think? This article is republished from The Conversation under a Creative Commons license. Read the original article. Ben Rider-Stokes receives funding from the Science and Technology Facilities Council (STFC).
Yahoo
20-06-2025
- Science
- Yahoo
The intriguing phenomena we can see in the skies this week
The summer evenings offer us the opportunity to sight some rather intriguing and beguiling phenomena. Noctilucent clouds, (NLCs), make for an interesting spectacle after sunset, observable with the naked eye and quite eerie in appearance. Around two hours after the Sun has set and looking above the northwest horizon, watch for wispy threads of cloud with a distinct blue and silver tinge to them. Taken from the Latin for 'night-shining', NLCs are formed by sunlight reflecting off high-altitude ice crystals that are positioned right on the edge of space. The time period after sunset is crucial if we are to catch NLCs, as around 90 minutes to two hours after the Sun has dipped below the horizon is when the necessary angle occurs for sunlight to catch the crystals and illuminate that part of the sky with this enchanting effect. The beautiful and captivating sight sees the highest clouds in our atmosphere, about 50 miles above the Earth's surface, seem to glow and shimmer with this mesmerizing blue or silvery guise. In the summertime the mesosphere, (the third layer of the Earth's atmosphere where meteorites burn up), becomes cold enough to allow ice to form on suspended dust particles that are floating around in the clouds. These particles may originate from meteorites falling from space, but equally so from other sources, possible volcanic, with the recent Mount Etna eruption billowing tons of debris into the atmosphere. In fact, the first NLCs observations were recorded in 1885, two years after the eruption of Krakatoa, which may or may not have something to do with their appearance. Eruptions aside, rockets that have blasted off from Earth leave particle emissions from their exhaust systems, all contributing to the array of debris circulating in our atmosphere. NLC's have been given a different name when seen from space looking back on Earth; polar mesospheric clouds, or (PMCs). However, the Earth is not the only place NLC's have been witnessed. Launched in June 2003, Mars Express was not only the first European mission to Mars, but the first planetary mission operated entirely by Europe. There were reports of NLC's made three years into the Mars Express mission in 2006, with NASA's Curiosity Mars rover confirming the presence of NLC's in 2019. Readers may well recall all the media hype over Asteroid 2024 YR4, which earlier this year was once considered the highest impact risk to Earth ever recorded. Earlier this week, NASA announced that previously collected data on the asteroid that has been reanalysed now reveals that the 174 to 220 feet-long chunk of rock is more likely to hit the Moon in 2032. During the week ahead, watch for Mars in the evening sky as it moves its way slowly night by night, left to right, above the bright star Regulus in the constellation of Leo, the Lion, situated above the western horizon. The International Space Station continues its early summer break and cannot be seen across our region at present. Send your astrophotography pictures to: thenightsky@
New York Times
19-06-2025
- Science
- New York Times
Edward Anders, Who Duped Nazis and Illuminated the Cosmos, Dies at 98
Edward Anders, a cosmochemist who unraveled mysteries about the solar system and the wildfires that helped wipe out the dinosaurs — and who then, in retirement, uncovered the identities of thousands of Jews from his hometown who were killed in the Holocaust — died on June 1 in San Mateo, Calif. He was 98. His death, in an assisted living facility, was confirmed by his son, George. Professor Anders emigrated to the United States in 1949, a few months after being called to testify at the Nuremberg trials about Nazi brutality in Liepaja, Latvia, in 1941 — events that he and his mother survived after she tricked soldiers into believing that she was of Aryan descent. His father wasn't as fortunate. Settling in New York City, Edward enrolled at Columbia University and studied chemistry. One day, his professor — a curator at the American Museum of Natural History — brought a handful of meteorite rocks to pass around in class. 'I found them tremendously exciting,' Professor Anders said in a 2001 interview with the journal Meteoritics & Planetary Science. 'I would even use the word romantic. Here were samples from far beyond the Earth's orbit, older than any rock on Earth, and you can get your hands on them, and even do respectable research on them.' Professor Anders's research turned out to be more than merely respectable. At the University of Chicago, his academic home for more than 30 years beginning in 1955, he conducted a series of groundbreaking studies into the early history of the solar system. He demonstrated that meteorites were fragments from asteroids and not, as was believed at the time, debris from the moon or comets. He quantified the elements of the solar system in a journal article that has been cited more than 14,000 times. And he uncovered evidence of the global wildfires that helped lead to the dinosaurs' extinction. Want all of The Times? Subscribe.
