Woo-hoo! Astronomers have their first image of a planet forming around its parent star. A group at the Max Planck Institute for Astronomy in Germany captured the thrilling photo of a young planet named PDS 70b in orbit around the orange star PDS 70. They used the SPHERE instrument on the European Southern Observatory’s Very Large Telescope (VLT) — one of the most powerful planet-hunting instruments ever made — to show the planet clearing a broad path through a dusty disk surrounding the star. Our solar system’s planets are thought to have formed from material in disks just like these more than 4.5 billion years ago.
The SPHERE instrument also enabled the team to measure the brightness of the planet at different wavelengths or colors of light to discover that the planet was ensconced in clouds. PDS70b is located about 1.9 billion miles (3 billion km) from its host star, about the same distance Uranus is from the sun. It resembles the gas giant planet Jupiter but it’s several times more massive and also much hotter with temperatures of around 1,830° F (1,000° C), more than twice as hot as Mercury and Venus.
“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, who lead the team behind the discovery of PDS 70’s still-forming planet.
As it revolves around PDS 70, the planet cuts a path through the primordial disk of dust and gas around the star, creating a giant “hole” in the center. These inner gaps have been known and photographed for decades, but astronomers could only speculate that hidden planets sculpted them. Now we can see the planet for the first time.
This glimpse of planetary youth was made possible by the SPHERE instrument, which studies exoplanets and disks by blocking the light from a star with a coronagraph and using clever observing strategies and data processing techniques to filter out the signal of the faint planetary companions around bright young stars.
I like looking at the photo and imagining the Earth kicking up the dust as it swung around the sun so long ago. Back then, the planet’s surface was molten rock with a suffocating atmosphere of hydrogen sulfide, methane, and 10 to 200 times as much carbon dioxide as today’s atmosphere, much of it originating in volcanoes. It took half a billion years for the surface to cool enough for liquid water to pool and then another billion and a half for early life to arrive at photosynthesis. Tiny bacteria used water, carbon dioxide and sunlight to survive and in the process released oxygen, a crucial gas necessary for our survival.