Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published April 17 in the journal Nature, shows that the atmospheres of Mars and Earth diverged in important ways very early in the 4.6 billion year evolution of our solar system.
Heather Franz, a former University of Maryland research associate who now works on the Curiosity rover science team at the NASA Goddard Space Flight Center, led the study with James Farquhar, co-author and UMD geology professor. The researchers measured the sulfur composition of 40 Mars meteorites—a much larger number than in previous analyses. Of more than 60,000 meteorites found on Earth, only 69 are believed to be pieces of rocks blasted off the Martian surface.
The meteorites are igneous rocks that formed on Mars, were ejected into space when an asteroid or comet slammed into the red planet, and landed on Earth. The oldest meteorite in the study is about 4.1 billion years old, formed when our solar system was in its infancy. The youngest are between 200 million and 500 million years old.
A meteorite with the mass of a small car crashed into the Moon last September, according to Spanish astronomers. The impact, the biggest seen to date, produced a bright flash and would have been easy to spot from the Earth. The scientists publish their description of the event in the journal Monthly Notices of the Royal Astronomical Society.
The Moon lacks the atmosphere that prevents small rocks from space from reaching the surface of the Earth. The result is very visible – vast numbers of craters large and small cover the whole of our nearest neighbour and record 4.5 billion years of collisions that span the history of the Solar system.
Although there is almost no chance of a very large object striking the Moon or planets, collisions with smaller objects are very common even today. The odds of seeing one of these by chance are pretty poor, so scientists have set up networks of telescopes that can detect them automatically.
The annual Geminid meteor shower, one of the best shooting-star displays each year, returns to our skies late this week. Skygazers and nature enthusiasts throughout the Northern Hemisphere will be out watching. Anyone can join in. You need no equipment and no special knowledge.
Every year in mid-December, Earth passes through a stream of rock bits that are being shed by a superheated asteroid named 3200 Phaethon. In 2013 we should see the meteor shower at its most active from 9 or 10 p.m. (local time) on Friday December 13th until the first light of dawn Saturday morning.
“We’ll have interference from moonlight in the sky this year,” says Robert Naeye, editor in chief of Sky & Telescope magazine, “but the brighter meteors will shine through anyway. You’ll probably see quite a few.”
Earth’s most eminent emissary to Mars has just proven that those rare Martian visitors that sometimes drop in on Earth — a.k.a. Martian meteorites — really are from the Red Planet. A key new measurement of Mars’ atmosphere by NASA’s Curiosity rover provides the most definitive evidence yet of the origins of Mars meteorites while at the same time providing a way to rule out Martian origins of other meteorites.
The new measurement is a high-precision count of two forms of argon gas—Argon-36 and Argon-38–accomplished by the Sample Analysis at Mars (SAM) instrument on Curiosity. These lighter and heavier forms, or isotopes, of argon exist naturally throughout the solar system. But on Mars the ratio of light to heavy argon is skewed because a lot of that planet’s original atmosphere was lost to space, with the lighter form of argon being taken away more readily because it rises to the top of the atmosphere more easily and requires less energy to escape. That’s left the Martian atmosphere relatively enriched in the heavier Argon-38.
A recently discovered mineral appears to be clear but may have a tinge of light blue. No matter its color, you won’t be able to make earrings from it.
For one, you can’t see the material with the naked eye. Hutcheonite, recently named after Lawrence Livermore meteorite researcher Ian Hutcheon, can be seen only with high powered scanning electron microscopes.
Known also by its chemical makeup, Ca3Ti2SiAl2O12, hutcheonite was discovered in a refractory inclusion in the Allende meteorite by Sasha Krot (University of Hawaii) and Chi Ma (Caltech) and named in honor of Hutcheon, who has made numerous contributions to the study of meteorites and what they can tell us about the evolution of the early solar system.
This weekend, as millions of people gaze up at the stars and wait for Perseid meteors to streak across the sky, one would hardly think that these awe-inspiring “shooting stars” are also a source of atmospheric pollution.
However, meteors, like those from this month’s Perseid meteor shower, burn up high in the Earth’s atmosphere leaving behind gases. “It’s a form of natural pollution,” says Gemini Observatory’s Chad Trujillo who heads up the facility’s state-of-the-art Adaptive Optics (AO) program.
“One of the gases left behind by meteors is sodium, which collects in a layer about 60 miles (90 kilometers) above the Earth,” says Trujillo (see animation). “The reason astronomers are so fond of this particular pollution layer is because we can make it glow by using a sodium laser to excite this sodium and produce temporary, artificial stars wherever we like. Believe it or not,” jokes Trujillo, “there aren’t enough stars in the sky for astronomers!”
Full Story: http://www.gemini.edu/node/12050
Comets and meteorites contain clues to our solar system’s earliest days. But some of the findings are puzzle pieces that don’t seem to fit well together. A new set of theoretical models from Carnegie’s Alan Boss shows how an outburst event in the Sun’s formative years could explain some of this disparate evidence. His work could have implications for the hunt for habitable planets outside of our solar system. It is published by The Astrophysical Journal.
One way to study the solar system’s formative period is to look for samples of small crystalline particles that were formed at high temperatures but now exist in icy comets. Another is to analyze the traces of isotopes—versions of elements with the same number of protons, but a different number of neutrons—found in primitive meteorites. These isotopes decay and turn into different, so-called daughter, elements. The initial abundances of these isotopes tell researchers where the isotopes may have come from, and can give clues as to how they traveled around the early solar system.
Stars are surrounded by disks of rotating gas during the early stages of their lives. Observations of young stars that still have these gas disks demonstrate that sun-like stars undergo periodic bursts, lasting about 100 years each, during which mass is transferred from the disk to the young star.