Scientists announced Monday that the James Webb Space Telescope had directly observed the key chemical carbon dioxide in planets outside of our solar system for the first time ever.
According to a study published in The Astrophysical Journal, the gas giants cannot support extraterrestrial life, but they do provide clues to a long-standing mystery about how distant planets form.
The HR 8799 system, 130 light years from Earth, is only 30 million years old, compared to our solar system’s 4.6 billion years. According to the study, a team of US researchers used Webb to directly detect carbon dioxide in the atmospheres of all four of the system’s known planets.
“Webb’s new images of two iconic systems, HR 8799 and 51 Eridani , and their planets have stunned researchers, and provided additional information into the chemical make-up of the young gas giants,” a statement from NASA read.
They used Webb’s coronagraph instruments, which block the light from bright stars to provide a better view of the planets that orbit them.
“It is like putting your thumb up in front of the sun when you are looking up in the sky,” lead study author William Balmer, an astrophysicist at Johns Hopkins University, told AFP.
Normally, the Webb telescope only sees exoplanets when they pass in front of their host star.
Webb used this “transiting method” to detect CO2 in the atmosphere of the gas giant WASP-39 in 2022.
However, in this latest discovery, “we are actually seeing the light that is emitted from the planet itself, as opposed to the fingerprint of that light from the host star,” Balmer explained.
This is not an easy task; Balmer compared it to using a torch to find fireflies near a lighthouse.
While these gas giants may not be able to support life, they may have moons that can, he added.
Missions are currently underway to investigate whether there is life in the vast oceans beneath the icy shells of several of Jupiter’s moons.
“Key piece of proof”
Carbon dioxide (CO2) is necessary for life on Earth, so it is a prime target in the search for life elsewhere.
CO2 condenses into small ice particles in the deep cold of space, and its presence can shed light on planetary formation.
Jupiter and Saturn are thought to have formed through a “bottom up” process in which a collection of tiny, icy particles merged into a solid core that then sucked in gas to grow into giants, according to Balmer.
According to Balmer, the new discovery is a “key piece of proof” that distant planets can form in the same way that planets in our own solar system do.
However, it is unclear how widespread this phenomenon is throughout the universe.
“Our hope with this kind of research is to understand our own solar system, life, and ourselves in the comparison to other exoplanetary systems, so we can contextualize our existence,” Balmer told me. “We want to take pictures of other solar systems to see how they compare to our own. From there, we can try to figure out how weird or normal our solar system is.”
Astronomers have discovered nearly 6,000 exoplanets, many of which are massive — but none of them are known to be habitable.
The “huge leap forward we need to make” is to focus on smaller Earth-sized worlds, according to Balmer.
NASA’s Nancy Grace Roman space telescope will use a coronagraph to accomplish this shortly after its scheduled launch in 2027.
Last year, the Webb telescope found carbon dioxide and hydrogen peroxide on the surface of Pluto’s largest moon, Charon.
Balmer hopes to use Webb to observe more four-planet systems, but noted that future funding was now uncertain.
Last week, the Trump administration announced the dismissal of NASA’s chief scientist, implying that further cuts were on the way for the US space agency.