Have We Been to Uranus? We Asked a NASA Expert: Episode 56

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Have we ever been to Uranus?

The answer is simple, yes, but only once. The Voyager II spacecraft flew by the planet Uranus back in 1986, during a golden era when the Voyager spacecraft explored all four giant planets of our solar system. It revealed an extreme world, a planet that had been bowled over onto its side by some extreme cataclysm early in the formation of the solar system.

That means that its seasons and its magnetic field get exposed to the most dramatic seasonal variability of any place that we know of in the solar system. The atmosphere was a churning system made of methane and hydrogen and water, with methane clouds showing up as white against the bluer background of the planet itself.
The densely packed ring system is host to a number of very fine, narrow and dusty rings surrounded by a collection of icy satellites. And those satellites may harbor deep, dark, hidden oceans beneath an icy crust of water ice.

Taken together, this extreme and exciting system is somewhere that we simply must go back to explore and hopefully in the next one to two decades NASA and the European Space Agency will mount an ambitious mission to go out there and explore the Uranian system. It’s important not just for solar system science, but also for the growing field of exoplanet science. As planets of this particular size, the size of Uranus, about four times wider than planet Earth, seem to be commonplace throughout our galaxy.

So how have we been to Uranus? Yes, but it’s time that we went back.

[END VIDEO TRANSCRIPT]

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Hubble Helps Determine Uranus’ Rotation Rate with Unprecedented Precision

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An international team of astronomers using the NASA/ESA Hubble Space Telescope has made new measurements of Uranus’ interior rotation rate with a novel technique, achieving a level of accuracy 1,000 times greater than previous estimates. By analyzing more than a decade of Hubble observations of Uranus’ aurorae, researchers have refined the planet’s rotation period and established a crucial new reference point for future planetary research.

These images from the NASA/ESA Hubble Space Telescope showcase the dynamic aurora on Uranus in October 2022. These observations were made by the Space Telescope Imaging Spectrograph (STIS) and includes both visible and ultraviolet data. An international team of astronomers used Hubble to make new measurements of Uranus’ interior rotation rate by analyzing more than a decade of the telescope’s observations of Uranus’ aurorae. This refinement of the planet’s rotation period achieved a level of accuracy 1000 times greater than previous estimates and serves as a crucial new reference point for future planetary research.ESA/Hubble, NASA, L. Lamy, L. Sromovsky

Determining a planet’s interior rotation rate is challenging, particularly for a world like Uranus, where direct measurements are not possible. A team led by Laurent Lamy (of LIRA, Observatoire de Paris-PSL and LAM, Aix-Marseille Univ., France), developed an innovative method to track the rotational motion of Uranus’ aurorae: spectacular light displays generated in the upper atmosphere by the influx of energetic particles near the planet’s magnetic poles. This technique revealed that Uranus completes a full rotation in 17 hours, 14 minutes, and 52 seconds — 28 seconds longer than the estimate obtained by NASA’s Voyager 2 during its 1986 flyby.

“Our measurement not only provides an essential reference for the planetary science community but also resolves a long-standing issue: previous coordinate systems based on outdated rotation periods quickly became inaccurate, making it impossible to track Uranus’ magnetic poles over time,” explains Lamy. “With this new longitude system, we can now compare auroral observations spanning nearly 40 years and even plan for the upcoming Uranus mission.”

This image of Uranus’ aurorae was taken by the NASA/ESA Hubble Space Telescope on 10 October 2022. These observations were made by the Space Telescope Imaging Spectrograph (STIS) and includes both visible and ultraviolet data. An international team of astronomers used Hubble to make new measurements of Uranus’ interior rotation rate by analyzing more than a decade of the telescope’s observations of Uranus’ aurorae. This refinement of the planet’s rotation period achieved a level of accuracy 1000 times greater than previous estimates and serves as a crucial new reference point for future planetary research.ESA/Hubble, NASA, L. Lamy, L. Sromovsky

This breakthrough was possible thanks to Hubble’s long-term monitoring of Uranus. Over more than a decade, Hubble has regularly observed its ultraviolet auroral emissions, enabling researchers to produce magnetic field models that successfully match the changing position of the magnetic poles with time.

“The continuous observations from Hubble were crucial,” says Lamy. “Without this wealth of data, it would have been impossible to detect the periodic signal with the level of accuracy we achieved.”

Unlike the aurorae of Earth, Jupiter, or Saturn, Uranus’ aurorae behave in a unique and unpredictable manner. This is due to the planet’s highly tilted magnetic field, which is significantly offset from its rotational axis. The findings not only help astronomers understand Uranus’ magnetosphere but also provide vital information for future missions.

These findings set the stage for further studies that will deepen our understanding of one of the most mysterious planets in the Solar System. With its ability to monitor celestial bodies over decades, the Hubble Space Telescope continues to be an indispensable tool for planetary science, paving the way for the next era of exploration at Uranus.

These results are based on observations acquired with Hubble programs GO #12601, 13012, 14036, 16313 and DDT #15380 (PI: L. Lamy). The team’s paper was published in Nature Astronomy.

The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA. Läs mer…

Eclipses, Science, NASA Firsts: Heliophysics Big Year Highlights 

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One year ago today, a total solar eclipse swept across the United States. The event was a cornerstone moment in the Heliophysics Big Year, a global celebration of the Sun’s influence on Earth and the entire solar system. From October 2023 to December 2024 — a period encompassing two solar eclipses across the U.S., two new NASA heliophysics missions, and one spacecraft’s history-making solar flyby — NASA celebrated the Sun’s widespread influence on our lives.  

An annular (or “ring of fire”) solar eclipse occurred Oct. 14, 2023, and kicked off the Helio Big Year with a bang. Millions of people across North America witnessed the Moon crossing in front of the Sun, creating this brilliant celestial event. NASA’s live broadcast had more than 11 million views across different platforms.  

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On Oct. 14, 2023, an annular solar eclipse crossed North, Central, and South America. Visible in parts of the United States, Mexico, and many countries in South and Central America, millions of people in the Western Hemisphere were able to experience this “ring of fire” eclipse. NASA’s official broadcast and outreach teams were located in Kerrville, TX, and Albuquerque, NM, to capture the event and celebrate with the communities in the path of annularity. Credit: NASA/Ryan Fitzgibbons 

Before the eclipse, NASA introduced the 2023 Eclipse Explorer, an interactive map to explore eclipse details for any location in the United States. NASA shared tips on eclipse safety, including through a video with NSYNC’s Lance Bass and even with an augmented reality filter. 

Scientists also studied conditions during the annular eclipse with sounding rockets, balloons, and amateur radio.  

On April 8, 2024, millions of people across North America experienced a total solar eclipse that darkened parts of 15 U.S. states in the path of totality.  

Ahead of the event, NASA hosted a widespread safety campaign, handed out over 2 million solar viewing glasses, and produced an interactive map to help viewers plan their viewing experience. On eclipse day, NASA also hosted a live broadcast from locations across the country, drawing over 38 million views. 

Researchers studied the eclipse and its effects on Earth using a variety of techniques, including international radar networks, scientific rockets, weather balloons, and even high-altitude NASA WB-57 jets. Several NASA-funded citizen science projects also conducted experiments. These projects included more than 49,000 volunteers who contributed an astounding 53 million observations.  

“We have opened a window for all Americans to discover our connection to the Sun and ignited enthusiasm for engaging with groundbreaking NASA science, whether it’s through spacecraft, rockets, balloons, or planes,” said Kelly Korreck, a Heliophysics program scientist at NASA Headquarters in Washington. “Sharing the excitement of NASA heliophysics with our fellow citizens has truly been amazing.” 

NASA’s heliophysics missions gather data on the Sun and its effects across the solar system.  

The Atmospheric Waves Experiment (AWE) mission launched from NASA’s Kennedy Space Center in Florida Nov. 9, 2023, and was installed on the International Space Station nine days later. This mission studies atmospheric gravity waves, how they form and travel through Earth’s atmosphere, and their role in space weather. 

On Nov. 4, 2024, the Coronal Diagnostic Experiment (CODEX) mission also launched to the space station, where it studies the solar wind, with a focus on what heats it and propels it through space.  

The Aeronomy of Ice in the Mesosphere (AIM) mission ended after 16 years studying Earth’s highest clouds, called polar mesospheric clouds.  

NASA’s Ionospheric Connection Explorer (ICON) also ended after three successful years studying the outermost layer of Earth’s atmosphere, called the ionosphere. 

Voyager has been operating for more than 47 years, continuing to study the heliosphere and interstellar space. In October 2024, the Voyager 1 probe stopped communicating. The mission team worked tirelessly to troubleshoot and ultimately reestablish communications, keeping the mission alive to continue its research.  

While the goal of the NASA heliophysics fleet is to study the Sun and its influence, these missions often make surprising discoveries that they weren’t originally designed to. From finding 5,000 comets to studying the surface of Venus, NASA highlighted and celebrated these bonus science connections during the Helio Big Year. 

Similar to Earth, the Sun has its own seasons of activity, with a solar minimum and solar maximum during a cycle that lasts about 11 years. The Helio Big Year happened to coincide with the Sun’s active period, with NASA and NOAA announcing in October 2024 that the Sun had reached solar maximum, the highest period of activity. Some of the largest solar storms on current record occurred in 2024, and the largest sunspot in nearly a decade was spotted in the spring of 2024, followed by a colossal X9.0 solar flare Oct. 3, 2024.  

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Sunspots are cooler, darker areas on the solar surface where the Sun’s magnetic field gets especially intense, often leading to explosive solar eruptions. This sunspot group was so big that nearly 14 Earths could fit inside it! The eruptions from this region resulted in the historic May 2024 geomagnetic storms, when the aurora borealis, or northern lights, were seen as far south as the Florida Keys.Credit: NASA/Beth Anthony

Viewers across the U.S. spotted auroras in their communities as a result of these storms, proving that you can capture amazing aurora photography without advanced equipment. 

NASA’s Parker Solar Probe holds the title as the closest human-made object to the Sun. On Dec. 24, 2024, Parker made history by traveling just 3.8 million miles from the Sun’s surface at a whopping 430,000 miles per hour.  

”Flying this close to the Sun is a historic moment in humanity’s first mission to a star,” said Nicky Fox, associate administrator, Science Mission Directorate, NASA Headquarters. 

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Controllers have confirmed NASA’s mission to “touch” the Sun survived its record-breaking closest approach to the solar surface on Dec. 24, 2024. Credit: NASA/Joy Ng

Parker Solar Probe’s close approach capped off a momentous Heliophysics Big Year that allowed NASA scientists to gather unprecedented data and invited everyone to celebrate how the Sun impacts us all. In the growing field of heliophysics, the Helio Big Year reminded us all how the Sun touches everything and how important it is to continue studying our star’s incredible influence.  

Though the Helio Big Year is over, heliophysics is only picking up its pace in 2025. We remain in the solar maximum phase, so heightened solar activity will continue into the near future. In addition, several new missions are expected to join the heliophysics fleet by year’s end. 

The PUNCH mission, a set of four Sun-watching satellites imaging solar eruptions in three dimensions, and EZIE, a trio of Earth-orbiting satellites tracing the electrical currents powering Earth’s auroras, have already launched. The LEXI instrument, an X-ray telescope studying Earth’s magnetosphere from the Moon, also launched through NASA’s CLPS (Commercial Lunar Payload Services) initiative. 

Future missions slated for launch include TRACERS, which will investigate the unusual magnetic environment near Earth’s poles, and ESCAPADE, venturing to Mars to measure the planet’s unique magnetic environment. 

The last two missions will share a ride to space. The Carruthers Geocorona Observatory will look back at home, studying ultraviolet light emitted by the outermost boundaries of our planet’s atmosphere. The IMAP mission will instead look to the outermost edges of our heliosphere, mapping the boundaries where the domain of our Sun transitions into interstellar space. 

By Desiree ApodacaNASA’s Goddard Space Flight Center Läs mer…