Somewhere about 390 light-years away, a young gas giant named HIP 65426 b has, for the first time, been seen directly by a telescope orbiting above the atmosphere, its faint light pulled out of the glare of the star it circles. The world is no stranger, having been glimpsed in 2017 from the ground, but Webb has now shown it through several infrared eyes, sharpening what humanity can know of distant worlds. It marks one more step in a long human effort to see beyond our own solar neighborhood, and it hints at many more planets waiting to be understood.
James Webb Telescope Captures First Direct Image of an Exoplanet Outside Our Solar System
At first all he could see was the star's light
Mark
So what is actually new here? The planet was found in 2017.
Mimi
The wavelength. Webb sees longer infrared light than the ground-based images used, and that reveals details Earth's glowing atmosphere hides.
Luke
And it isn't the first space-based direct image of an exoplanet. Hubble has done that. The claim is first for Webb.
Mark
Why is imaging a planet so hard?
Mimi
Stars outshine planets. This one is more than 10,000 times fainter than its star in the near-infrared, and a few thousand times fainter in the mid-infrared.
Mark
How did Webb manage it?
Mimi
Coronagraphs on two instruments, tiny masks that block starlight. Plus the planet sits about 100 times farther from its star than Earth does from the Sun, so it separates easily.
Luke
Worth noting the mass, six to 12 Jupiters, is a wide range. The team says these observations could narrow it, but that hasn't happened yet.
Mark
And the results are settled?
Luke
Not yet. The paper hasn't gone through peer review. The team is still preparing it.
Mimi
Carter's line stays with me, that at first all he could see was the star, and careful processing uncovered the planet.
Luke
Hopes of finding unknown planets are his expectation, not a result.
Le Pouls
- A planet ten thousand times fainter than its star had to be teased out of blinding starlight, and the team's margin for error was razor-thin.
- NASA's Webb telescope, using coronagraphic masks, turned a faint speck into a multi-filter image that astronomers had long hoped to capture.
- Researchers are now sifting through their data and preparing a peer-reviewed paper that will test whether their mass estimates hold.
- The image has set the stage for the Roman Space Telescope, which will soon try an even more advanced coronagraph to chase planets like this one.
Somewhere about 390 light-years away, a young gas giant named HIP 65426 b has, for the first time, been seen directly by a telescope orbiting above the atmosphere, its faint light pulled out of the glare of the star it circles. The world is no stranger, having been glimpsed in 2017 from the ground, but Webb has now shown it through several infrared eyes, sharpening what humanity can know of distant worlds. It marks one more step in a long human effort to see beyond our own solar neighborhood, and it hints at many more planets waiting to be understood.
On September 1, 2022, NASA announced that its James Webb Space Telescope had taken the first direct image of a planet beyond our solar system. The world, HIP 65426 b, appears through four infrared filters as a slightly different glow in each. It is a gas giant with no solid surface, roughly six to twelve times Jupiter's mass, and it is young by planetary standards, only about 15 to 20 million years old.
The planet was first found in 2017 by astronomers using the SPHERE instrument on a telescope in Chile, but Webb sees it at longer infrared wavelengths that ground telescopes cannot reach, because Earth's atmosphere glows in the infrared. The real difficulty was contrast: the planet is more than ten thousand times dimmer than its star. Webb's coronagraphs, tiny masks that block starlight, made the capture possible, and the planet's distance from its star, about a hundred times Earth's distance from the Sun, helped separate it from the glare.
The observations were led by Sasha Hinkley of the University of Exeter, who called the moment transformative, and the image analysis was carried out by Aarynn Carter of the University of California, Santa Cruz. Carter described the work as digging for treasure: at first he saw only starlight, and careful processing revealed the planet beneath it. The team is now preparing a paper for peer review, and Carter believes this is only the beginning of many exoplanet images to come. The Roman Space Telescope, due later this decade, will test an even more advanced coronagraph.
On September 1, 2022, NASA posted a short message announcing that its James Webb Space Telescope had taken its first direct image of a planet outside our solar system. The image shows a world called HIP 65426 b through four different infrared light filters. In each one, the planet appears as a slightly different blob of light.
The planet is a gas giant, which means it has no rocky surface and could not be habitable. Its mass is estimated at six to 12 times that of Jupiter, and the team says these observations could narrow that range. It is young by planetary standards, about 15 to 20 million years old, against the 4.5 billion years of Earth.
It is not a new discovery. Astronomers found HIP 65426 b in 2017 using the SPHERE instrument on the European Southern Observatory's Very Large Telescope in Chile, and they imaged it then at short infrared wavelengths. What Webb adds is a view at longer infrared wavelengths. Ground-based telescopes cannot see those details because Earth's atmosphere glows in the infrared. The source also notes that this is not the first direct exoplanet image taken from space, since the Hubble Space Telescope has captured some before.
The difficulty lies in the contrast. Stars are far brighter than the planets that orbit them. HIP 65426 b is more than 10,000 times fainter than its host star in the near-infrared and a few thousand times fainter in the mid-infrared. Distance helps in this case. The planet sits about 100 times farther from its star than Earth does from the Sun, so Webb can easily separate the two in the image.
Webb's Near-Infrared Camera (NIRCam) and its Mid-Infrared Instrument (MIRI) both carry coronagraphs, sets of tiny masks that block starlight. That is what makes direct imaging of certain exoplanets possible. Sasha Hinkley, an associate professor of physics and astronomy at the University of Exeter in the United Kingdom, led the observations with a large international collaboration. He called it a transformative moment for Webb and for astronomy generally, and said the coronagraphs suppressed the star's light impressively well.
Aarynn Carter, a postdoctoral researcher at the University of California, Santa Cruz, led the analysis of the images. He compared getting the result to digging for space treasure. At first, he said, all he could see was starlight, but careful image processing let him remove it and uncover the planet. The varying shapes of the blob in each filter come from the particulars of Webb's optical system and how it carries light through its different optics.
Webb is an international mission led by NASA with the European Space Agency and the Canadian Space Agency as partners. The researchers are still analyzing the data and preparing a paper to submit to journals for peer review. Carter said the most exciting part is that this is only the beginning, with many more exoplanet images to come that will shape understanding of their physics, chemistry and formation, and perhaps reveal planets not yet known.
NASA's Nancy Grace Roman Space Telescope, slated to launch later this decade, will demonstrate an even more advanced coronagraph. The peer-reviewed paper on HIP 65426 b is the next thing to watch.
Citations marquantes
This is a transformative moment, not only for Webb but also for astronomy generally.— Sasha Hinkley, University of Exeter
There are many more images of exoplanets to come, and we may even discover previously unknown planets.— Aarynn Carter, University of California, Santa Cruz (paraphrased)
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