Why are Neptune and Uranus Different Colors?

A comparison of Uranus (left) and Neptune (right). Credit: Left: NASA/JPL-Caltech, Right: NASA

Uranus and Neptune are similar planets in many ways. Both are ice giant worlds, both have atmospheres rich in methane, and both have a bluish color. But while Uranus has a pale blue-green hue, Neptune has a deep blue color. But why? Why would two planets so similar in size and composition appear so different? According to a recent study, the answer lies in their aerosols.

Continue reading “Why are Neptune and Uranus Different Colors?”

Here are Hubble’s 2021 Photos of the Outer Solar System

The NASA/ESA Hubble Space Telescope has completed its annual grand tour of the outer Solar System for 2021. This is the realm of the giant planets — Jupiter, Saturn, Uranus, and Neptune — extending as far as 30 times the distance between Earth and the Sun. Unlike the rocky terrestrial planets like Earth and Mars that huddle close to the Sun’s warmth, these far-flung worlds are mostly composed of chilly gaseous soups of hydrogen, helium, ammonia, and methane around a packed, intensely hot, compact core. Note: The planets are not shown to scale in this image. Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley) and the OPAL team

If we had to rely solely on spacecraft to learn about the outer planets, we wouldn’t be making great progress. It takes a massive effort to get a spacecraft to the outer Solar System. But thanks to the Hubble Space Telescope, we can keep tabs on the gas giants without leaving Earth’s orbit.

Continue reading “Here are Hubble’s 2021 Photos of the Outer Solar System”

Why do Uranus and Neptune Have Magnetic Fields? Hot ice

The outer “ice giant” planets, Neptune and Uranus, have plenty of mysteries.  One of the biggest is where exactly they got their magnetic fields.  They are strong at that, with Neptune’s being twenty-seven times more powerful than Earth’s, while Uranus’ varies between ?  and four times Earth’s strength.  Chaos rules in these electromagnetic environments, making them exceptionally hard to both understand and model.  Now a team of researchers led by Dr. Vitali Prakpenka of the University of Chicago thinks they might have found the underlying cause of both the field’s strength and its randomness – “hot ice.”

Continue reading “Why do Uranus and Neptune Have Magnetic Fields? Hot ice”

Giant Balls of Mush Made From Ammonia and Water Form in the Atmospheres of Uranus and Neptune

One advantage to planetary science is that insights from one planet could explain phenomena on another.  We understand Venus’ greenhouse gas effect from our own experience on the Earth, and Jupiter and Saturn share some characteristics.  But Jupiter also provides insight into other, farther out systems, such as Uranus and Neptune.  Now, a discovery from a spacecraft orbiting Jupiter might have solved a long-standing mystery about Uranus and Neptune – where has all the ammonia gone?

Continue reading “Giant Balls of Mush Made From Ammonia and Water Form in the Atmospheres of Uranus and Neptune”

What Mission Could Detect Oceans at Uranus’ Moons?

Exploration of ocean worlds has become a hot topic of late, primarily due to their role as a potential harbor for alien life.  Moons that have confirmed subsurface oceans garner much of the attention, such as Enceladus and Europa.  But they may not be the only ones.  Uranus’ larger moonsMiranda, Ariel, and Umbriel could potentially also have subsurface oceans even farther out into the solar system.  We just haven’t sent any instruments close enough to be able to check.  Now a team led by Dr. Corey Cochrane at NASA’s Jet Propulsion laboratory has done some preliminary work to show that a relatively simple flyby of the Uranian system with an averagely sensitive magnetometer could provide the data needed to determine if those larger moons harbor subsurface oceans.  This work is another step down the path of expanding what we think of as habitable environments in the solar system.

Continue reading “What Mission Could Detect Oceans at Uranus’ Moons?”

Both Uranus and Neptune Have Really Bizarre Magnetic Fields

These composite images show Uranian auroras, which scientists caught glimpses of through the Hubble in 2011. In the left image, you can clearly see how the aurora stands high above the planet's denser atmosphere. These photos combine Hubble pictures made in UV and visible light by Hubble with photos of Uranus' disk from the Voyager 2 and a third image of the rings from the Gemini Observatory in Hawaii and Chile. The auroras are located close to the planet's north magnetic pole, making these northern lights. Credit: NASA, ESA, and L. Lamy (Observatory of Paris, CNRS, CNES)

The magnetic fields of Uranus and Neptune are really, seriously messed up. And we don’t know why.

Continue reading “Both Uranus and Neptune Have Really Bizarre Magnetic Fields”

Uranus X-Rays are Probably Reflected Sunlight, but There Could be Another Source as Well

X-rays offer a unique insight into the astronomical world.  Invisible to the naked eye, most commonly they are thought of as the semi-dangerous source of medical scans.  However, X-ray observatories, like the Chandra X-ray Observatory are capable of seeing astronomical features that no other telescope can.  Recently scientists found some of those X-rays coming from a relatively unexpected source – Uranus.

Continue reading “Uranus X-Rays are Probably Reflected Sunlight, but There Could be Another Source as Well”

Uranus’ Moons are Surprisingly Similar to Dwarf Planets in the Kuiper Belt

Ö. H. Detre et al./MPIA

Astronomer William Herschel discovered Uranus—and two of its moons—230 years ago. Now a group of astronomers working with data from the telescope that bears his name, the Herschel Space Observatory, have made an unexpected discovery. It looks like Uranus’ moons bear a striking similarity to icy dwarf planets.

The Herschel Space Observatory has been retired since 2013. But all of its data is still of interest to researchers. This discovery was a happy accident, resulting from tests on data from the observatory’s camera detector. Uranus is a very bright infrared energy source, and the team was measuring the influence of very bright infrared objects on the camera.

The images of the moons were discovered by accident.

Continue reading “Uranus’ Moons are Surprisingly Similar to Dwarf Planets in the Kuiper Belt”

The Moons of Uranus Are Fascinating Enough On Their Own That We Should Send a Flagship Mission Out There

What’s the most interesting fact you know about Uranus? The fact that its rotational axis is completely out of line with every other planet in the solar system?  Or the fact that Uranus’ magnetosphere is asymmetrical, notably tilted relative to its rotational axis, and significantly offset from the center of the planet?  Or the fact that it’s moons are all named after characters from Shakespeare or Alexander Pope?

All of those facts (with the exception of the literary references) have come from a very limited dataset. Some of the best data was collected during a Voyager 2 flyby in 1986. Since then, the only new data has come from Earth-based telescopes.  While they’ve been steadily increasing in resolution, they have only been able to scratch the surface of what may be lurking in the system surrounding the closest Ice Giant.  Hopefully that is about to change, as a team of scientists has published a white paper advocating for a visit from a new Flagship class spacecraft.

Continue reading “The Moons of Uranus Are Fascinating Enough On Their Own That We Should Send a Flagship Mission Out There”

A Simulation of Sunsets on Other Worlds: From Venus to Titan


When we think of exploring other planets and celestial bodies, we tend to focus on the big questions. How would astronauts live there when they’re not working? What kind of strategies and technology would be needed for people to be there long term? How might the gravity, environment, and radiation effect humans who choose to make places like the Moon, Mars, and other bodies place their home? We tend to overlook the simple stuff…

For example, what will it be like to look up at the sky? How will Earth, the stars, and any moon in orbit appear? And how will it look to watch the sun go down? These are things we take for granted here on Earth and don’t really ponder much. But thanks to NASA, we now have a tool that simulates what sunsets would look like from other bodies in the Solar System – from the hellish surface of Venus to the dense atmosphere of Uranus.

Continue reading “A Simulation of Sunsets on Other Worlds: From Venus to Titan”