Free Astronomy Magazine May-June 2022

48 MAY-JUNE 2022 ASTRO PUBLISHING T his image shows the loca- tions of 115 potential rogue planets, highlighted with red circles, recently dis- covered by a team of as- tronomers in a region of the sky occupied by Upper Scor- pius and Ophiucus. Rogue planets have masses compara- ble to those of the planets in our Solar System, but do not orbit a star and instead roam freely on their own. The exact number of rogue planets found by the team is between 70 and 170, depending on the age assumed for the study re- gion. This image was created assuming an intermediate age, resulting in a number of planet candidates in between the two extremes of the study. [ESO/N. Risinger (skysurvey.org) ] A stronomers have used ESO telescopes to detect at least 70 rogue planets in our Milky Way, the largest group to date. Learn more about these elusive cosmic nomads in this video summarising the discovery! [ESO] The team also used data from the European Space Agency’s Gaia satellite, marking a huge success for the collaboration of ground- and space-based telescopes in the exploration and understanding of our Universe. The study suggests there could be many more of these elusive, starless planets that we have yet to discover. “There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star,” Bouy explains. By studying the newly found rogue planets, astronomers may find clues to how these mysterious objects form. Some scientists believe rogue planets can form from the collapse of a gas cloud that is too small to lead to the formation of a star, or that they could have been kicked out from their parent system. But which mechanism is more likely re- mains unknown. Further advances in technology will be key to unlocking the mystery of these nomadic plan- ets. The team hopes to continue to study them in greater detail with ESO’s forthcoming Extremely Large Telescope (ELT), currently under con- struction in the Chilean Atacama Desert and due to start observations later this decade. “These objects are extremely faint and little can be done to study them with current fa- cilities,” says Bouy. “The ELT will be absolutely crucial to gathering more information about most of the rogue planets we have found.” !