The bizarre orientation of the planet, which orbits the sun tipped on its side, reveals that its inner core has a stronger influence on its weather patterns than the distant star. The green and blue regions show where the atmosphere is clear, allowing sunlight to penetrate deep into Uranus.
The bizarre orientation of the planet, which orbits the sun tipped on its side, reveals that its inner core has a stronger influence on its weather patterns than the distant star. The green and blue regions show where the atmosphere is clear, allowing sunlight to penetrate deep into Uranus.
Little is known about the Uranian atmosphere as to date only one spacecraft, Voyager 2, which passed by the planet in 1986, obtained some valuable compositional data. No other missions to Uranus are currently scheduled.
Simon said that temperature is a large part of the reason for Uranus' blandness. The ice giant doesn't have a lot of heat. In fact, it is the only planet that doesn't give off more heat than it receives from the sun, she said. That slows down the rise and fall of heat that would otherwise drive storms.
Like its neighbor Neptune, Uranus likely formed closer to the Sun and moved to the outer solar system about 4 billion years ago, where it is the seventh planet from the Sun. Uranus is one of two ice giants in the outer solar system (the other is Neptune).
Orbit and Rotation Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees – possibly the result of a collision with an Earth-sized object long ago.
Uranus has a relatively circular orbit, so it remains at about the same distance from the Sun throughout its long year. But the axis of Uranus is tilted by 98 degrees! This causes 21-year-long seasons and unusual weather, although one thing that is certain: it is always cold.
Most planetary axes are perpendicular to the orbital plane. But Uranus's axis is extremely tilted to 97.7º and its pole is pointed toward the equatorial plane of the other planets. This extreme tilt leads to the radical seasons that the planet experiences and makes the planet have unusual days at the poles.
Like the other gas giants, Uranus has an atmosphere composed of mostly hydrogen, followed by helium and a little methane....QUICK FACTS. (Data is from NASA Goddard)Average distance from Sun1.8 billion milesMoons27 knownAtmosphereHydrogen (82.5%), Helium (15%), Methane (2.3%)9 more rows
84 yearsUranus / Orbital period
Bottom line: The rotation axis of Uranus has a very large tilt that causes extreme seasonal changes. This results in increased activity in its atmosphere during the planet's spring and fall seasons.
This is because of its peculiar chemical composition, where water and other volatiles (i.e. ammonia, methane, and other hydrocarbons) in its atmosphere are compressed to the point where they become solid. In addition to that, it also has a very long orbital period.
Uranus was likely hit by a very large planetoid early in its history, causing it to rotate "on its side," 90 degrees away from its orbital motion. Venus rotates backwards compared to the other planets, also likely due to an early asteroid hit which disturbed its original rotation.
Because Uranus is about 15 times more massive than the Earth, its gravitational pull would start massively affecting our planet. Volcanoes would begin erupting uncontrollably, and tremendous earthquakes would get in on the act, destroying Earth from the inside. And the stink.
On the gas giants, storms in the lower altitudes create these waves, which propagate toward the higher altitudes and generate heat, Melin said.
thickUranus has a thick atmosphere made of methane, hydrogen, and helium. Uranus is the only planet that spins on its side. Uranus spins the opposite direction as Earth and most other planets.
Yes, there is really 'diamond rain' on Uranus and Neptune.
Scientists define the surface as the region where the atmospheric pressure exceeds one bar, the pressure found on Earth at sea level. Just above the "surface" of Uranus lies the troposphere, where the atmosphere is the densest.
Atmospheric composition. Uranus' atmosphere is predominantly made up of hydrogen and helium. Unlike Jupiter and Saturn, these light gases dominate only the outer edges of the planet, but are not a significant contributor to the rocky interior. The dull blue color of Uranus is caused by the presence of methane, which absorbs red light.
Ammonia and hydrogen sulfide clouds come next. Finally, thin methane clouds lay on the top. The troposphere extends 30 miles (50 kilometers) from the surface of the planet. Radiation from the sun and from space heats the stratosphere of Uranus from minus 370 F (minus 218 C) to minus 243 F (minus 153 C).
This makes the atmosphere of Uranus the coldest in the solar system. Within the troposphere are layers of clouds — water clouds at the lowest pressures, with ammonium hydrosulfide clouds above them. Ammonia and hydrogen sulfide clouds come next. Finally, thin methane clouds lay on the top.
Hydrocarbons are less abundant in the atmosphere of Uranus than they are of other giant planets, however. The stratosphere reaches almost 2,500 miles (4000 km) above Uranus.
The dull blue color of Uranus is caused by the presence of methane, which absorbs red light. "I think poor Uranus is misunderstood, actually," planetary scientist Amy Simon said on NASA's Gravity Assist podcast. "Uranus is very bland in appearance most of the time. It's kind of a pale blue planet.
Uranus' Atmosphere: Layers of Icy Clouds. The seventh planet in the solar system — and the largest of the ice giants — Uranus has an atmosphere more comparable with Neptune than with Saturn and Jupiter. Known as ice giants, the two most distant planets from the sun have atmospheres that are heavily dominated by ices.
A lone moon hurtles past as the Cassini spacecraft stares into the clouds of Saturn. Cassini monitored clouds near Saturn's equator for nearly 20 hours during an important series of observations d...
The moon's night side is partly lit by reflected light from Saturn. North on Mi...
Saturn's B and C rings shine in diffuse, scattered light as the Cassini spacecraft looks on the planet's night side. The southern hemisphere is lit by sunlight reflecting off the rings, while the n...
This anaglyph from NASA's Dawn spacecraft shows degraded craters shows partially degraded craters and ridges in asteroid Vesta's Pinaria quadrangle. You need 3D glasses to view this image.
This Cassini image is one of the highest-resolution views ever taken of Saturn's moon Pandora, a moon that orbits just outside the narrow F ring.
Uranus took shape when the rest of the solar system formed about 4.5 billion years ago, when gravity pulled swirling gas and dust in to become this ice giant. Like its neighbor Neptune, Uranus likely formed closer to the Sun and moved to the outer solar system about 4 billion years ago, where it is the seventh planet from the Sun.
And Uranus makes a complete orbit around the Sun (a year in Uranian time) in about 84 Earth years (30,687 Earth days).
Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees – possibly the result of a collision with an Earth-sized object long ago. This unique tilt causes the most extreme seasons in the solar system. For nearly a quarter of each Uranian year, the Sun shines directly over each pole, plunging the other half of the planet into a 21-year-long, dark winter.
Magnetosphere. Rings. Moons. Potential for Life. Introduction. The seventh planet from the Sun with the third largest diameter in our solar system, Uranus is very cold and windy. The ice giant is surrounded by 13 faint rings and 27 small moons as it rotates at a nearly 90-degree angle from the plane of its orbit.
Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees—possibly the result of a collision with an Earth-sized object long ago. This unique tilt causes the most extreme seasons in the solar system.
From an average distance of 1.8 billion miles (2.9 billion kilometers), Uranus is 19.8 astronomical units away from the Sun.
Auroras on Uranus are not in line with the poles (like they are on Earth, Jupiter and Saturn) due to the lopsided magnetic field. The magnetosphere tail behind Uranus opposite the Sun extends into space for millions of miles. Its magnetic field lines are twisted by Uranus’ sideways rotation into a long corkscrew shape.
Given the storm in Uranus’s lower atmosphere, Melin suspects that another factor could be at work: low-amplitude “acoustic waves” —also known as gravity waves—generated by huge, turbulent storms. These waves originate from disturbances, like ripples in a pond. On Earth, gravity waves come from violent thunderstorms or when wind blows over a mountain. On the gas giants, storms in the lower altitudes create these waves, which propagate toward the higher altitudes and generate heat, Melin said.
The Sun warms the gas giants, but because those planets are so large and far away, scientists know that solar photons don’t supply enough energy to heat their upper atmospheres to current temperatures.
Models of Jupiter, Saturn, Uranus, and Neptune predict that the temperatures of their upper atmospheres—the zones of dilute gases far above the planets’ frigid cloud tops—should be around 200 kelvins, or –73° C. However, when the two Voyager spacecraft zipped by those gas giants in the late 1980s, scientists discovered that the planets’ outermost atmospheres were much hotter than expected—nearing 1000 kelvins, or more than 700°C.
The fact that the reversal happened relatively quickly means that “something dramatic has changed.”
Although close monitoring has shown that Uranus’s upper atmosphere underwent consistent cooling over the past 20 years, measurements since 2014 by University of Leicester’s Henrik Melin and colleagues revealed a reversal toward heating.
In 2010, a huge storm erupted in Saturn’s lower atmosphere, and scientists witnessed the evolution of a region of hot gases that rose into the upper atmosphere.
Scientific evidence suggests that Jupiter and Saturn hold extremely hot cores left over from their formation about 4.5 billion years ago, but the core of Uranus generates relatively little heat. Also, the process that creates auroras on Earth—high-energy solar particles interacting with the planet’s magnetic field—can cause heating. However, because the gas giants are so huge and rotate so fast, this heat circles the poles without spreading globally, so it wouldn’t account for the global upper atmospheric heating that’s been observed, Melin said.
As we explore exoplanets and their distant solar systems – or think about planetary moons, or asteroids – who knows what range of differences we’ll find? But we do know this. Uranus has bizarre seasons, in contrast to Earth and the other major planets in this solar system. It’s because Uranus’ spin axis is extremely tilted with respect to its orbit around the sun. Compared to the other planets – which spin elegantly nearly upright as they orbit our local star – Uranus almost seems as if it’s rolling around the sun, like a rolling ball.
Earth’s axis is tilted 23.5 degrees from perpendicular with respect to the plane of our orbit around the sun. Uranus’s axis is tilted at 98 degrees! So Uranus is tilted nearly sideways to the plane of the solar system, the single flat sheet of space in which nearly all the planets and moons orbit.
And, speaking of its orbit, Uranus orbits 1.8 billion miles (2.8 nillion km) from the sun. And so Uranus takes a long time to orbit the sun once. Its “year” is 84 Earth-years long. That makes each of its four seasons 21 years long. That’s another reason we on Earth think of Uranus’ seasons as strange.
As a result, in summer, one pole of Uranus plus a large section of that pole’s hemisphere faces the sun continuously for 21 years. Meanwhile, the other half of Uranus – the winter half – is in darkness for 21 years. That’s a long polar night, and a long midnight sun!
Instead, as on Earth, the planet’s tilt is what gives Uranus its four seasons.
This 2004 image of Uranus was taken using filters designed to isolate very specific wavelengths of light to bring out features – in this case, variations in the altitude and thickness of clouds – that would otherwise not be visible. Images of the area around the planet were enhanced to show the rings and some of the planet’s moons. Image via NASA / Erich Karkoschka.
Earth- and space-based observatories have observed this change over decades of Uranus-watching. The Voyager 2 spacecraft is the only craft from Earth that has ever flown past Uranus. That was in 1986. Voyager 2 encountered this world during its southern hemisphere summer. The spacecraft saw Uranus as blue and featureless.
Adams and Leverrier predicted the position of Neptune, based on its perturbations of:
William Herschel thought he had found a comet when he spotted the green disk of:
Astronomy Ch . 13 Uranus and Neptune: The outer Worlds of the Solar System