Why are Uranus and Neptune Different Colors? Haze

NASA’s Voyager 2 spacecraft captured these views of Uranus (on the left) and Neptune (on the right) during its flybys of the planets in the 1980s.

Way back in the late 1980s, the Voyager 2 spacecraft visited Uranus and Neptune. During the flybys, we got to see the first close-up views of those ice giants. Even then, planetary scientists noticed a marked color difference between the two. Yes, they both sport shades of blue. But, if you look closely at Uranus, you see a featureless pale blue planet. Neptune, on the other hand, boasts interesting clouds, dark banding, and dark spots that come and go. They’re all set against a darker blue backdrop.

So, why the difference? Planetary scientists have long suspected aerosols (droplets of gas that have liquids or dust suspended in them) in each atmosphere. But, according to a team of scientists studying the layers of the planets, the hazes those aerosols create may only be part of the story.

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

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?”

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”

Uranus’ Rings are Surprisingly Bright in Thermal Emissions

Composite image of Uranus’s atmosphere and rings at radio wavelengths, taken with the ALMA array in December 2017. The image shows thermal emission, or heat, from the rings of Uranus for the first time, enabling scientists to determine their temperature: a frigid 77 Kelvin (-320 F). Dark bands in Uranus’s atmosphere at these wavelengths show the presence of molecules that absorb radio waves, in particular hydrogen sulfide gas. Bright regions like the north polar spot (yellow spot at right, because Uranus is tipped on its side) contain very few of these molecules. (UC Berkeley image by Edward Molter and Imke de Pater)

During the late 1970s, scientists made a rather interesting discovery about the gas giants of the Solar System. Thanks to ongoing observations using improved optics, it was revealed that gas giants like Uranus – and not just Saturn – have ring systems about them. The main difference is, these ring systems are not easily visible from a distance using conventional optics and require exceptional timing to see light being reflected off of them.

Another way to study them is to observe their planet in infrared or radio wavelengths. This was recently demonstrated by a team of astronomers who conducted observations of Uranus using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Telescope (VLT). In addition to obtaining temperature readings from the rings, they confirmed what many scientists have suspected about them for some time.

Continue reading “Uranus’ Rings are Surprisingly Bright in Thermal Emissions”

Something Twice the Size of Earth Slammed into Uranus and Knocked it Over on its Side

Between 3 to 4 billion years ago, a body twice the size of Earth impacted Uranus, knocking the ice giant onto its side. Image Credit: Jacob A. Kegerreis/Durham University
Between 3 to 4 billion years ago, a body twice the size of Earth impacted Uranus, knocking the ice giant onto its side. Image Credit: Jacob A. Kegerreis/Durham University

Astronomers think they know how Uranus got flipped onto its side. According to detailed computer simulations, a body about twice the size of Earth slammed into Uranus between 3 to 4 billion years ago. The impact created an oddity in our Solar System: the only planet that rotates on its side.

A study explaining these findings was presented at the American Geophysical Union’s (AGU) Fall Meeting in Washington DC held between December 10th to 14th. It’s led by Jacob Kegerreis, a researcher at Durham University. It builds on previous studies pointing to an impact as the cause of Uranus’ unique orientation. Taken altogether, we’re getting a clearer picture of why Uranus rotates on its side compared to the other planets in our Solar System. The impact also explains why Uranus is unique in other ways.
Continue reading “Something Twice the Size of Earth Slammed into Uranus and Knocked it Over on its Side”

Exploring the Ice Giants: Neptune and Uranus at Opposition for 2018

The existence of Neptune was inferred by its gravitational effect on other bodies long before it was ever observed. Image Credi: NASA/JPL
The existence of Neptune was inferred by its gravitational effect on other bodies long before it was ever observed. Image Credi: NASA/JPL

Have you seen the outer ice giant planets for yourself?

This week is a good time to check the most difficult of the major planets off of your life list, as Neptune reaches opposition for 2018 on Friday, September 7th at at ~18:00 Universal Time (UT)/2:00 PM EDT. And while it may not look like much more than a gray-blue dot at the eyepiece, the outermost ice giant world has a fascinating tale to tell. Continue reading “Exploring the Ice Giants: Neptune and Uranus at Opposition for 2018”

New Insights Into What Might Have Smashed Uranus Over Onto its Side

Uranus
A new study indicates that a massive impact may be why Uranus orbits on its side. Credit: NASA/JPL/Voyager mission

The gas/ice giant Uranus has long been a source of mystery to astronomers. In addition to presenting some thermal anomalies and a magnetic field that is off-center, the planet is also unique in that it is the only one in the Solar System to rotate on its side. With an axial tilt of 98°, the planet experiences radical seasons and a day-night cycle at the poles where a single day and night last 42 years each.

Thanks to a new study led by researchers from Durham University, the reason for these mysteries may finally have been found. With the help of NASA researchers and multiple scientific organizations, the team conducted simulations that indicated how Uranus may have suffered a massive impact in its past. Not only would this account for the planet’s extreme tilt and magnetic field, it would also explain why the planet’s outer atmosphere is so cold.

Continue reading “New Insights Into What Might Have Smashed Uranus Over Onto its Side”