Far out in space — about 910 light-years from Earth — astronomers have spotted a giant planet almost the size of Jupiter circling a sun-like star. The planet, called NGTS-39b, is what scientists call a "warm Jupiter" because it's a gas giant like our Jupiter but orbits much closer to its star, making it toasty at around 519 Kelvin (about 475 degrees Fahrenheit). The discovery, published in July 2026, shows how much scientists are learning about the different types of planets that exist beyond our solar system.
The star itself, named NGTS-39, is remarkably similar to our own sun — just about 16 percent bigger and heavier, with a surface temperature of 6,053 Kelvin. Scientists estimate it is 2.2 billion years old, slightly younger than our 4.6-billion-year-old sun.
The planet takes 58.2 days to complete one orbit around its star, traveling at a distance of about 0.31 times the distance from Earth to the sun. That's much closer than even Mercury's orbit around our sun. NGTS-39b has a radius about 1.09 times that of Jupiter and a mass 1.47 times greater, making it a heavyweight among gas giants. Its density is slightly higher than Jupiter's, which suggests it may contain more heavy elements like rock and ice in its atmosphere.
The discovery was an international effort. NASA's Transiting Exoplanet Survey Satellite, called TESS for short, first picked up a signal that something was passing in front of the star in observations between 2019 and 2024. Scientists study exoplanets by watching for tiny drops in a star's light when a planet moves across it — like a mini-eclipse. Then a team led by Ioannis Apergis at the University of Warwick in the UK used 12 robotic telescopes in Chile, part of something called the Next Generation Transit Survey (NGTS), to confirm the signal. They combined these observations with measurements from two special instruments, CORALIE and HARPS, which can detect the slight "wobble" a planet creates in its star's motion.
What makes NGTS-39b especially exciting is its temperature. At 519 Kelvin, it sits right in a sweet spot for studying planetary atmospheres. Scientists say this is warm enough to study chemical reactions in the atmosphere but not so hot that the planet becomes a fuzzy blur in their telescopes. Researchers noted the planet could teach us about atmospheric chemistry in this temperature range, something that has been difficult to study before.
There's even more mystery: the data hints that another planet may be orbiting farther out from the star. That would make NGTS-39 a two-planet system, though astronomers need more observations to be sure.
The team behind the discovery says NGTS-39b is a valuable addition to the small but growing family of transiting gas giants on wide orbits — planets that cross in front of their stars as seen from Earth, making them easier to study. Each new world teaches astronomers something new about how planets form, migrate, and evolve around distant suns.