In a new study, astronomers compared high-resolution images of Uranus from the NASA/ESA Hubble Space Telescope with more distant views from NASA’s New Horizons spacecraft. Their results could serve as “ground truth” observations to use as a baseline for interpreting exoplanet direct imaging data from future observatories.
In this image, two three-dimensional shapes of Uranus (top) are compared to the actual views of Uranus from Hubble (bottom left) and New Horizons (bottom right). Image credits: NASA/ESA/STScI/Samantha Hasler, MIT/Amy Simon, NASA-GSFC/New Horizons Planetary Science Theme Team/Joseph DePasquale, STScI/Joseph Olmsted, STScI.
Direct imaging of exoplanets is an important technique for understanding their potential habitability and provides new clues to the origin and formation of our own solar system.
Astronomers use both direct imaging and spectroscopy to collect light from observed planets and compare their brightness at different wavelengths.
However, exoplanets are notoriously difficult to image because they are so far away.
Their images are just pinpoints, so they aren’t as detailed as our close-up view of the world around the sun.
Astronomers can also directly image exoplanets only in “partial phase,” when only part of the planet is illuminated by its star as seen from Earth.
Uranus was an ideal target as a test to understand future long-range observations of exoplanets by other telescopes for several reasons.
First, many known exoplanets are gas giants with similar properties. Also, at the time of the observation, New Horizons was on the far side of Uranus, 10.5 billion kilometers (6.5 billion miles) away, and was able to study the twilight crescent moon. This is not possible from Earth.
At that distance, New Horizons’ view of the planet was just a few pixels wide of its color camera (Multispectral Visible Imaging Camera).
Meanwhile, Hubble’s high resolution allowed it to see atmospheric features such as clouds and storms on the dayside of the gas world from its low orbit, 2.7 billion kilometers (1.7 billion miles) from Uranus. .
Samantha Hassler, an astronomer at the Massachusetts Institute of Technology, said: “We expected Uranus to look different depending on the observation filter, but New Horizons data taken from different perspectives actually show that Uranus looks different than expected.'' It turned out to be much darker than that.”
The gas giant planets in our solar system have dynamic and variable atmospheres with changing cloud cover. How common is this in exoplanets?
Knowing the details of what Uranus’ clouds looked like from Hubble will allow researchers to test what they can interpret from New Horizons’ data.
In the case of Uranus, both Hubble and New Horizons observed that the brightness does not change as the planet rotates. This indicates that the cloud characteristics are not changing due to the rotation of the planet.
But the significance of New Horizons’ detection has to do with how the planet reflects light at a different phase than what Hubble and other observatories on or near Earth can see.
New Horizons showed that exoplanets can be dimmer than predicted at partial and high phase angles, and that their atmospheres reflect light differently at partial phase.
“The groundbreaking New Horizons study of Uranus from a vantage point that cannot be observed by any other means adds to the mission’s treasure trove of new scientific knowledge and, like many other data sets obtained on the mission, will Dr. Alan Stern, Principal Investigator of New Horizons and Research Scientist at the Southwest Research Institute, said:
“NASA’s next Nancy Grace Roman Space Telescope, scheduled to launch by 2027, will use a coronagraph to block out starlight and directly observe gas giant exoplanets,” Hassler said. Ta.
“NASA’s Habitable World Observatory, in its early planning stages, will be the first telescope specifically designed to search for biosignatures in the atmospheres of rocky Earth-sized planets orbiting other stars. .”
“Studying how known benchmarks like Uranus appear in distant images will help us have more solid expectations as we prepare for these future missions. And it will help our It’s critical to success.”
Scientists are result this week’s DPS56Annual Meeting of the Planetary Science Division of the American Astronomical Society.
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S. Hassler others. 2024. Observations of Uranus at high phase angles by New Horizons Ralph/MVIC. DPS56
This article has been adapted from the original release by NASA.
Source: www.sci.news
