Evidence for the world's first 'satellite to revolve a planet outside the solar system' is discovered

" Satellite " refers to a celestial body that revolves around the planet like the Moon for the Earth. Satellites have not been discovered on planets outside the solar system until now, but researchers have reported that they have found evidence that a satellite exists on a planet outside the solar system.

Evidence for a large exomoon orbiting Kepler-1625b | Science Advances
http://advances.sciencemag.org/content/4/10/eaav 1784

Have scientists found a moon around a planet outside the solar system?
https://mashable.com/article/moon-found-outside-solar-system-exomoon/

Hubble finds compelling evidence for a moon outside the Solar System | ESA / Hubble
https://www.spacetelescope.org/news/heic1817/

Satellites in the solar system have been discovered in celestial bodies such as Mars other than the Earth, but satellites have not been discovered so far for planets outside the solar system. For stars outside the solar system where the distance from the earth is far away, the stars that emit the light themselves are relatively easy to find, while planets and satellites that do not emit light themselves are difficult to find.

Graduate student Alex Teachy and Collaborator David Kipping studying astronomy at Columbia University observe the extrasolar planet about 8000 light years away from the earth called " Kepler-1625 " with the Hubble Space Telescope did. Kepler - 1625 is a gas planet that has several times the mass of Jupiter , and that it is revolving with a fixed star keeping the distance to the sun and the earth.

Mr. Teach and Mr. Kipping who observed the Kepler - 1625 cross the front of the fixed star said that the planet crosses the front of the star over 19 hours and the deflection and fluctuation of the light that can be observed by stellar light being blocked by the planet We have confirmed that. In addition, it took three and a half hours after Kepler - 1625 passed in front of a fixed star, although it was weaker than when the planet passed through, it seems that we could confirm the decrease of the star 's light again.

The identity of a celestial object that blocked the light of a star following Kepler - 1625 is likely to be a Kepler - 1625 satellite. Unfortunately, the observation time scheduled before the satellite completely crossed the fixed stars ended and could not be observed until the end, but Mr. Kipping said that the observation which seems to be evidence of the solar system outside satellite I am very excited. The satellite considered to be present in Kepler - 1625 is named "Kepler - 1625 b - i " and is presumed to be a huge satellite with a diameter comparable to Neptune .

Teachy says that after the Kepler - 1625 the light blocked celestial body may be another planet, but during the observation of the Hubble Space Telescope it is unlikely that other planets will cross the stars. Also, when observing the moment when Kepler - 1625 crosses the front of a fixed star in the Hubble Space Telescope, Techey naturally predicted what planetary passage would happen from when. However, actually it seems that the passage of the planet began one hour earlier than the prediction, "The reason that Kepler-1625 deviated from the predicted position was because of the gravitational attraction between the giant satellite and each other" Teachy thinks.

In principle other planets may have influenced the orbit of Kepler - 1625, but in the four - year observation made by the Hubble Space Telescope, such a planet was not found. Teachy says that Kepler-1625-i is a satellite large enough to overturn the image of a conventional satellite, "It may be a stimulus to reconsider the theory that satellites are created, bringing new insights into the formation of the planetary system" And it explains.