A transmission spectrum made from a single observation using Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) reveals atmospheric characteristics of the hot gas giant exoplanet WASP-96 b. A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves across the star, to the unfiltered starlight detected when the planet is beside the star. Each of the 141 data points (white circles) on this graph represents the amount of a specific wavelength of light that is blocked by the planet and absorbed by its atmosphere. Credit: NASA, ESA, CSA, ST
Webb’s Gigantic Mirror and Precision Instrumentation Join Forces To Capture the Most Detailed Spectrum of an Exoplanet Atmosphere Ever
In a remarkable dream come true for exoplaneteers, 
A light curve from Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) shows the change in brightness of light from the WASP-96 star system over time as the planet transits the star. A transit occurs when an orbiting planet moves between the star and the telescope, blocking some of the light from the star. This observation was made using NIRISS’s Single-Object Slitless Spectroscopy (SOSS) mode, which involves capturing the spectrum of a single bright object, like the star WASP-96, in a field of view. To capture these data, Webb stared at the WASP-96 star system for 6 hours 23 minutes, beginning about 2½ hours before the transit and ending about 1½ hours after the transit was complete. The transit itself lasted for just under 2½ hours. The curve includes a total of 280 individual brightness measurements – one every 1.4 minutes. Credit: NASA, ESA, CSA, STScI
Webb Reveals Steamy Atmosphere of Distant Exoplanet in Exquisite Detail
NASA’s James Webb Space Telescope has captured the distinct signature of water in the atmosphere surrounding a hot, puffy gas giant planet orbiting a distant Sun-like star. It also found evidence of clouds and haze.
The observation is the most detailed of its kind to date, demonstrating Webb’s incredible capability to analyze atmospheres hundreds of light-years away. It reveals the presence of specific gas molecules based on tiny decreases in the brightness of precise colors of light.
Over the past two decades, the Hubble Space Telescope has analyzed numerous exoplanet atmospheres , capturing the first clear detection of water in 2013. However, Webb’s immediate and more detailed observation marks an enormous leap forward in the quest to characterize potentially habitable planets beyond Earth.
WASP-96 b is one of more than 5,000 confirmed exoplanets in the
A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves across the star to the unfiltered starlight detected when the planet is beside the star. Researchers are able to detect and measure the abundances of key gases in a planet’s atmosphere based on the absorption pattern – the locations and heights of peaks on the graph. In the same way that people have distinctive fingerprints and
In addition, Webb’s extreme stability and its orbital location around Lagrange Point 2, roughly a million miles away from the contaminating effects of Earth’s atmosphere, makes for an uninterrupted view and clean data that can be analyzed relatively quickly.
The extraordinarily detailed spectrum – made by simultaneously analyzing 280 individual spectra captured over the observation – provides just a hint of what Webb has in store for exoplanet research. Over the coming year, researchers will use spectroscopy to analyze the surfaces and atmospheres of several dozen exoplanets, from small rocky planets to gas- and ice-rich giants. Nearly one-quarter of Webb’s Cycle 1 observation time is allocated to studying exoplanets and the materials that form them.
This NIRISS observation demonstrates that Webb has the power to characterize the atmospheres of exoplanets – including those of potentially habitable planets – in exquisite detail.
The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
NASA Headquarters oversees the mission for the agency’s Science Mission Directorate. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages Webb for the agency and oversees work on the mission performed by the Space Telescope Science Institute, Northrop Grumman, and other mission partners. In addition to Goddard, several NASA centers contributed to the project, including the agency’s Johnson Space Center in Houston, Jet Propulsion Laboratory in Southern California, Marshall Space Flight Center in Huntsville, Alabama, Ames Research Center in California’s Silicon Valley, and others.
NIRISS was contributed by the Canadian Space Agency. The instrument was designed and built by Honeywell in collaboration with the Université de Montréal and the National Research Council Canada.