Rox 42 b is a gas giant, approximately similar in size to Jupiter. Its mass and composition are still being studied, but it is believed to be significantly more massive than Earth. 

This planet is located about 500 light-years away in the constellation Pegasus. Its distance makes it an intriguing subject for ongoing observation and study. 

The atmospheric composition of Rox 42 b remains largely unknown due to limited observations. However, being a gas giant, it likely has a thick atmosphere dominated by hydrogen and helium, with potential traces of heavier elements. 

The study of Rox 42 b could help scientists better understand the formation and evolution of gas giants, particularly in relation to their host stars and surrounding environments. 

Discovery Method: Transit Method

Year Discovered: 2019

Details: Rox 42 b was discovered using the transit method, where astronomers observe dips in a star's brightness caused by a planet passing in front of it. This method allows researchers to infer the planet's size, orbit, and distance from its star.