Free Astronomy Magazine September-October 2018

47 SPACE CHRONICLES who lead the team behind the dis- covery of PDS 70’s still-forming planet. “The problem is that until now, most of these planet candi- dates could just have been features in the disc.” The discovery of PDS 70’s young companion is an exciting scientific result that has already merited fur- ther investigation. A second team, involving many of the same as- tronomers as the discovery team, including Keppler, has in the past months followed up the initial ob- servations to investigate PDS 70’s fledgling planetary companion in more detail. They not only made the spectacu- larly clear image of the planet shown here, but were even able to obtain a spectrum of the planet. Analysis of this spectrum indicated that its atmosphere is cloudy. PDS 70’s planetary companion has sculpted a transition disc — a pro- toplanetary disc with a giant “hole” in the centre. These inner gaps have been known about for decades and it has been speculated that they were produced by disc-planet inter- action. Now we can see the planet for the first time. A stronomers using the SPHERE instrument on ESO’s Very Large Telescope captured the first clear image of a planet caught in the act of form- ing in the dusty disc surrounding a young star. The young planet is carving a path through the primor- dial disc of gas and dust around the very young star PDS 70. The data sug- gest that the planet’s atmosphere is cloudy. [ESO] SEPTEMBER-OCTOBER 2018 of the planet at different wave- lengths, which allowed properties of its atmosphere to be deduced. The planet stands out very clearly in the new observations, visible as a bright point to the right of the blackened centre of the image. It is located roughly three billion kilome- tres from the central star, roughly equivalent to the distance between Uranus and the Sun. The analysis shows that PDS 70b is a giant gas planet with a mass a few times that of Jupiter. The planet's surface has a temperature of around 1000°C, making it much hotter than any planet in our own Solar System. The dark region at the centre of the image is due to a coronagraph, a mask which blocks the blinding light of the central star and allows astronomers to detect its much fainter disc and planetary compan- ion. Without this mask, the faint light from the planet would be ut- terly overwhelmed by the intense brightness of PDS 70. “These discs around young stars are the birthplaces of planets, but so far only a handful of observations have detected hints of baby planets in them,” explains Miriam Keppler,