Uranus is the seventh planet from the Sun
and the third-largest planet in the solar system.
It also may have the coldest interior, emitting far
less heat than its counterparts Jupiter, Saturn and Neptune.
It is known as an “ice giant” because it contains more ices,
including water, methane, and ammonia than Jupiter or Saturn.
And while NASA's learned a great deal about this planet over the last
three decades, there's a lot more waiting to be discovered.
Back in 1986,
NASA's Voyager 2 spacecraft flew by Uranus,
making it the first and only spacecraft to visit this distant planet.
Previous observations showed that Uranus has a unique tilt of its axis,
so it rotates almost on its side, causing its poles to actually face the Sun.
No other planet in our solar system has this feature.
In its quick sprint past Uranus, Voyager discovered
ten new moons orbiting the planet that had not been seen before.
And in the decades since, even more have been found.
During its encounter, Voyager also saw new faint rings
and explored the complex magnetosphere.
Voyager only briefly viewed the planet's five major moons:
Ariel, Miranda, Titania, Oberon and Umbriel.
These moons have a wide variety of terrains and geological features,
some of which indicate possible subsurface oceans.
Small Miranda has chaotic terrain, with deep canyons
and tall mountains, but is likely now frozen solid.
Ariel appears to have the youngest surface with few impact craters.
While Titania has a very old surface,
the lack of large craters and presence of a large canyon system
may indicate ancient resurfacing.
Oberon is also covered with craters and has valleys and large mountains.
Umbriel’s surface is the darkest of the Uranian moons
and it sports a strange polar ring.
The origin of this ring is still a mystery,
but scientists believe that it may have been formed by an icy impact.
Since Voyager, ground based telescopes
and the Hubble Space Telescope
have played the leading role in our understanding of Uranus.
Since 1992, Hubble has watched the slowly changing Uranian seasons,
including changes in its unusual pale blue color and polar hazes.
Telescopes have also revealed that Uranus has a complex weather system
with massive storms that can last for months or even years,
with wind speeds over 500 miles per hour.
The ongoing search for ocean worlds and life beyond Earth
makes Uranus an exciting target for the James Webb Space Telescope
and for future up close exploration.
New data will help scientists to understand the formation
and evolution of Uranus, as well as its moons and rings, and provide clues
as to whether liquid water may reside beneath their icy crusts.
The fascinating properties of this planet,
discovered in just the span of a few decades,
reveal that unlocking mysteries here
can help scientists learn, even more about our solar system, and our place in it.