Meteorite hunters in Michigan found six rocks on Thursday (January 18) that say they came from a spectacular fireball that lit the local skies earlier this week.
The team of Larry Atkins, Robert Ward and Darryl Landry made the findings in an isolated lake in Michigan, declined to reveal the exact location so as not to attract unwanted attention to the lake and its residents. In an interview with Space.com, Atkins said he plans to continue the search at least next week.
The first finding occurred around 9 a.m. EST (1300 GMT), and Atkins discovered a second himself 15 minutes later. "It looked like a perfect black coal briquette, with a bit of a snowdrift on top," Atkins told Space.com on Thursday. Based on his two decades of experience in meteorite hunting, rock fragments that remain after some space rock fireballs break into the atmosphere, he said there was no doubt it was from space. The rock appeared clearly on the fresh ice, although at a distance Atkins wondered if it was a small pile of leaves. [Small Michigan Meteor Packed a Seismic Punch, Experts Say]
The findings had masses between 20 and 100 grams, and were small enough to "fit in the palm of your hand," Atkins said. He added that from a quick glance at the meteorites, they all seem to be related and they all looked like common chondrites, the most common type of meteorite found on Earth. The team has already selected a sample they plan to send to the Chicago Field Museum, Atkins said. The rest will be kept for their personal collections, they said.
Atkins has been searching for space rocks for two decades. This discovery comes only two years after another team in which he participated found several space rocks from a Florida fireball. For this Michigan fireball, Atkins, who spends his winters in Arizona, made a special trip back to his hometown, Ann Arbor, to participate in the search.
Team member teammate Robert Ward also flew in from Arizona, arriving at 1:30 a.m. EST (0530 GMT) on January 18. At 3 a. m, he was already exploring for possible locations, based on radar information his team received from the American Meteor Society and NASA. His first discovery was around 10 a.m. – another chondrite, he said. Ward gave a telephone interview to Space.com yesterday (January 19) while he was on the ice, looking for more meteorites.
"The information was spectacular: it was a very quick discovery and everything was put together," Ward said, referring to the amount of information available to help him make the discovery. He has searched meteorites since he was 13 years old, approximately 28 years ago, and has made 600 different finds on all continents except Antarctica. "I'll be here until Sunday, but I can come back … later in a few weeks."
Public and professional participation
The emotion of the fireball sent to the people to the cold of Michigan hoping to find a space. Among them was the seismologist Larry Ruff of the University of Michigan, who thought it would be a fun idea to venture into the fresh snow and hunt meteorites. He did not find anything, but he enjoyed the experience, he said.
"It's been very cold here, but today was one of the warmest days," Ruff told Space.com in an interview on January 18, explaining that temperatures were then as high as 20 degrees Fahrenheit (minus 7 Celsius degrees). "That explains why everyone was happy to leave the house and look for some meteorites."
Ruff searched in a park along with Earth science professor James Gleason, who specializes in meteorite composition. The teachers met with many other meteorite seekers, too. Ruff joked that he was jealous that others had made the first findings, but added, "the area of the waste field is so big, and someone has to make a finding."
Ruff, who oversees the Ann Arbor seismic station at the University of Michigan, said the fireball produced one of the strongest seismic waves he has ever seen. He added that "seismic wave" did not mean an earthquake, but it meant a disturbance in the atmosphere.
Sightings in the Midwest
The American Meteor Society received 657 reports on the fireball since it lit the skies on Tuesday night (January 16), according to its website, with observers reporting from several states, including Michigan, Wisconsin, Iowa, Illinois, Indiana, Ohio, West Virginia and Pennsylvania. Some observers even saw it from the province of Ontario, in Canada.
"This was a very slow moving meteor – speed of approximately 28,000 miles per hour (45,000 km / h)," the AMS added in a press release issued on Wednesday (January 17). "This fact, combined with the brightness of the meteor (which suggests a rather large space rock), shows that the object penetrated deep into the atmosphere before breaking (which produced the sounds heard by at least 77 observers)."  The composition and size of the meteor are still not well understood, but early reports suggest it was only a few feet in size, rather than the impressive diameter of the 17-meter (51-foot) Chelyabinsk bolide. When that fireball exploded over Russia in 2013, it injured hundreds of people and caused property damage, mainly because the sonic wave of the meteorite broke the glass.
Meteorites range from the durable to the delicate. If the Michigan fireball was made of lesser material than iron or stone, exposure to the elements will erode any fragment quickly. That's why Ruff said it's important to get out quickly, to make sure that as much evidence as possible is gathered.
Record of the primitive solar system
More than 50,000 meteorites have been found only on Earth, according to NASA. Of them, approximately 99.8 percent comes from asteroids, small rocky bodies in our solar system. This means that meteorites serve as a record of the primitive solar system, since asteroids are leftover fragments of the small pieces of rock and gas that formed the planets about 4,500 to 4,600 million years ago.
"The study of meteorites tells us a lot about the earlier conditions and processes during formation and the earliest history of the solar system, such as the age and composition of solids, the nature of organic matter, temperatures reached on the surface and the interior of the asteroids, and the grade of the materials were impacted by the impacts, "said NASA officials.
This fireball over Michigan was too small to cause damage, but past events on Earth have done it. A meteorite attack on Earth about 66 million years ago is one of the main causes of extinction of dinosaurs. The impact left a crater 180 miles (300 kilometers) called Chicxulub, which is located in the Yucatan Peninsula. Another known impact site is Meteor Crater in Arizona, which is approximately 0.6 miles (1 km) wide. Craters are also found throughout the solar system: on the moon, on Mars and in many other places.
NASA has a Planetary Defense Coordination Office in charge of looking for potentially dangerous objects that move towards Earth. They have not yet seen an object that poses an imminent threat to life on Earth, but NASA and its partners continue to search, just in case. Scientists are also working on various technologies to divert or destroy threatening asteroids, such as lasers or missiles.
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