British researchers: in data from the Kepler telescope – thanks to the microlens effect – identified four planets the size of our earth, which seem to float freely through space.
In 2016, as part of its K2 mission, NASA’s Kepler space telescope took part in an observation campaign to find so-called microlensing events, which was flanked by large earth-based telescopes. Switches at the end of 2018 the NASA finally shut down the telescope due to lack of fuel. But the analysis of the data still brings something new to light. Researchers at the University of Manchester have now discovered four Earth-sized planets that seem to float through space without a star like our sun.
Such free-floating planets have been identified over and over again in the past few years. There are now a few dozen such discoveries in total. Because they do not orbit a star and are barely illuminated, the free-floating planets are difficult to find with the currently available methods. Researchers rely on the microlens effect caused by gravity. Planets can be identified from Earth based on the distortion of the light of a star as they pass.
The main reason why the search for free-floating planets with the microlens effect is so difficult is that one has to monitor millions of stars at the same time in order to find corresponding signals. In 2016, for example, the Kepler telescope was aligned every 30 minutes over a two-month period to a new sector of space. Study leader Iain McDonald describes described this process as “about as easy as looking for a single blink of a firefly in the middle of a freeway where you only have a smartphone”.
However, the data analysis now showed the success of the mission. The British scientists found 27 microlensing events in the data from the Kepler telescope. Four of the possible free-floating planets should correspond approximately to the size and mass of the earth. In any case, it is clear that the planets discovered are very far away. The scientists can only estimate the actual distance, however; it should be between 3,000 and 10,000 light years. In the future, better telescopes should enable new insights into the free-floating planets.
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