{"id":23626,"date":"2023-02-06T19:00:57","date_gmt":"2023-02-06T18:00:57","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=135107"},"modified":"2023-02-06T20:35:12","modified_gmt":"2023-02-06T19:35:12","slug":"how-scientists-uncovered-277-martian-meteorites-on-planet-earth","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/how-scientists-uncovered-277-martian-meteorites-on-planet-earth\/","title":{"rendered":"How scientists uncovered 277 Martian meteorites on planet Earth"},"content":{"rendered":"

There are 60,000 meteorites recorded meteorites on Earth. <\/p>

By Dr Alastair Gunn\n \t\t<\/p>

Published: Monday, 06 February 2023 at 12:00 am<\/p>

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There are several strands of evidence implying that some of the meteorites found on Earth actually originate from Mars<\/a>.\u00a0Scientists have used a technique called \u2018radiometric dating<\/a>\u2019 to determine the ages of these chunks of rock.<\/p>\n

The method, which is analogous to radiocarbon dating of organic material, looks at the ratios of certain radioactive isotopes in the meteorites. Since isotopes decay at well-determined rates, a comparison of their ratios reveals the time since the meteorite was formed, or at least the time since it was last heated.<\/p>\n

Most meteorites turn out to be about 4.56 billion years old, because they come from asteroids\u00a0that\u00a0date from the creation of the\u00a0Solar\u00a0System, 4.56 billion years ago. Anything younger than this must be from a planet or moon, the only places in the\u00a0Solar\u00a0System that could have formed rocks younger than 4.65 billion years.<\/p>\n

Scientists have found that the ratios of oxygen isotopes in meteorites are different for each \u2018parent body\u2019. The reasons for this are still unclear,\u00a0but it\u2019s probably related to the way the\u00a0Solar\u00a0System originally formed. Martian meteorites are found to have isotopic compositions that match the rocks of Mars. Furthermore, some Martian meteorites are found to have trapped gases<\/a> whose isotopic composition exactly matches that measured for the atmosphere on Mars. Taken together, these strands of evidence make the\u00a0meteorites\u2019\u00a0origin pretty certain:\u00a0they arrived here from Mars.<\/p>\n

But if these chunks of rock are from Mars, then how did they get to Earth? Scientists believe that, given a sufficiently powerful impact by a comet or asteroid, chunks of the Martian surface can be ejected into space. A small number of these could end up in orbits that put them on a collision course with Earth. Those chunks big enough to survive passage through Earth\u2019s atmosphere will reach the surface. To date, around 277 such \u2018Martian meteorites\u2019<\/a> have been found.<\/p>\n

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