The universe's oldest mystery: the "impossible" planet, aged 13 billion years, has been unveiled (photo).

Using the James Webb Space Telescope, astronomers have unveiled a long-standing mystery regarding the formation of planets in the early Universe. This enigma arose after the Hubble Space Telescope discovered the oldest known planet in the Universe over 20 years ago, a planet that formed at a time in cosmic history when astronomers believed such formation was impossible. The research has been published in The Astrophysical Journal, as reported by Live Science.

Stars are born from vast clouds of gas and dust. Once a star forms, the remaining gas and dust envelop it, creating a protoplanetary disk where planets develop. Astronomers previously thought that some of the first stars in the Universe could not have formed planets because their protoplanetary disks lacked sufficient heavy chemical elements like carbon and iron. These heavy elements are produced in the cores of stars through nuclear fusion and during a star's death in a supernova explosion. Astronomers believed that heavy elements were essential for protoplanetary disks to persist long enough to allow for planet formation. If protoplanetary disks could not exist for extended periods, then stars in the early Universe could not have planets.

However, in 2003, astronomers using the Hubble Space Telescope discovered a massive planet approximately 5,600 light-years away in the Milky Way, orbiting a star in the globular cluster M4. Globular clusters are among the oldest objects in the Universe, and thus contain very few heavy chemical elements. Nevertheless, astronomers determined that the planet, named PSR B1620-26b, is a gas giant that has existed for about 13 billion years. For comparison, the age of the Universe is estimated to be 13.8 billion years. This discovery indicated that planets could form in such an early Universe, despite it being previously deemed impossible.

To understand the conditions in the early Universe, scientists can study objects that share characteristics with the most ancient galaxies. One such object is the star cluster NGC 346 in the nearby Small Magellanic Cloud galaxy. This cluster contains almost no heavy chemical elements and is primarily composed of hydrogen and helium.

Initially, scientists observed NGC 346 using the Hubble Telescope. Astronomers found evidence that stable protoplanetary disks could exist around stars for 20 to 30 million years. This is about ten times longer than theories had predicted. To gather more data, astronomers utilized the Webb Telescope. New observations confirmed that even in environments poor in heavy chemical elements, protoplanetary disks can exist for extended periods, allowing for planet formation.

Thus, the mystery of the oldest known planet and similarly aged planets discovered later has been unraveled. The existence of these seemingly "impossible" planets can indeed be explained.

Scientists believe that protoplanetary disks around ancient stars existed for long durations because the lack of heavier chemical elements may have prevented the star from rapidly dispersing the disk with its radiation. This provided an opportunity for planets to form. On the other hand, astronomers suggest that the molecular cloud from which a star is created may be larger, meaning the protoplanetary disk could also be more massive initially, allowing it to persist for a longer time.