Saturn's North Pole Has Changed Color, But Why?

The observed color change in Saturn's north polar region between 2012 and 2016.Credit: NASA/JPL-Caltech/Space Science Institute/Hampton University

Spectacular photos captured by NASA's Cassini spacecraft reveal a curious color change over Saturn's north pole. The occurrence may be linked to seasonal changes and the planet's enormous hexagonal jet stream.

The images were captured by Cassini's wide-angle camera between 2012 and 2016. Photos from 2012 show a bluish halo over Saturn's north pole, while those taken in 2016 show the same area with a more golden hue.

Saturn's north pole has a unique, six-sided jet stream known as "the hexagon,"which is approximately 20,000 miles (32,000 kilometers) wide. Winds of this hexagonal vortex whip through the planet's atmosphere at approximately 200 mph (322 km/h). [Cassini Snaps New Views of Saturn's Hexagon (Video)]

Preliminary hypotheses suggest the color change observed in the atmosphere over Saturn's northern hemisphere could be associated with the jet stream. For instance, the hexagonal vortex may act as barrier and prevent surrounding particles from entering the area. In this case, the sky over Saturn's north pole would have been cleared of haze or aerosols during the seven-year-long Saturnian winter, according to a statement from NASA. Then, haze production would have ramped up again when the pole was exposed to sunlight.

"Scientists are investigating potential causes for the change in color of the region inside the north-polar hexagon on Saturn," NASA officials said in the statement. "The color change is thought to be an effect of Saturn's seasons. In particular, the change from a bluish color to a more golden hue may be due to the increased production of photochemical hazes in the atmosphere as the north pole approaches summer solstice in May 2017."

Photochemical hazes, or aerosols, are created from reactions between sunlight and the atmosphere. Saturn experienced equinox in August 2009, and since then has been subjected to continuous sunshine. During this time, photochemical aerosols have accumulated in the sky above Saturn's north pole, creating the golden haze observed today.

However, other factors, including changes in solar heating and wind patterns, could cause a shift in the planet's atmospheric circulation, officials said in the statement. These factors may also play a role in the observed color changes, the officials said.

The Cassini-Huygens spacecraft has been orbiting Saturn since 2004, and the mission is expected to come to a close in September 2017. Researchers will continue to study data collected from Cassini to get a better understanding of this curious color change.

What's Up with 'Niku'? Object's Weird Orbit Puzzles Scientists

An artist’s impression of a Kuiper Belt object (KBO), located about 4 billion miles from the Sun.

Credit: NASA, ESA, and G. Bacon (STScI)

A mysterious object in the outer reaches of the solar system is revolving around the sun in an abnormal way, and scientists currently cannot explain why.

The object has been nicknamed Niku, a Chinese adjective that means "rebellious," by the group of researchers who announced its discovery in August. This name was chosen because the object's orbit is retrograde, meaning it moves in the opposite direction of nearly everything else in the solar system.

Niku was discovered by researchers who used the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii, and it lies in the outer reaches of the solar system, about 35 times farther away from the sun than Earth, beyond the orbit of Neptune. [The Pan-STARRS Asteroid Hunting Telescope]


Niku's orbit is inclined at an extreme 110-degree tilt with respect to the relatively thin, flat zone in which the eight major planets of the solar system orbit. In contrast, most trans-Neptunian objects (TNOs) are in much less inclined orbits.

The retrograde and extremely tilted nature of the orbits of Niku and another TNO nicknamed "Drac" led the scientists to try to find out whether there were objects with similar orbital characteristics that were listed in the Minor Planet Center database (which contains information about more than 1,000 small bodies in the solar system). They discovered four other objects with orbits that were either retrograde or nearly retrograde (meaning is orbit is inclined by less than, but close to, 90 degrees) and were also highly tilted. Two of these objects are Centaurs — bodies that orbit between Jupiter and Neptune.

A gif showing Niku moving across the sky, taken with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii.

Credit: Panoramic Survey Telescope & Rapid Response System/PS1

The scientists were surprised to find that all six of these objects appear to orbit within a common plane.

"They're not randomly distributed in the sky — they all seem to be aligned," study co-author Matthew Payne, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, told Space.com.

Computer simulations that the researchers carried out suggest that Niku and Drac may have been in their orbits for hundreds of millions of years. In addition, the scientists suggest that there may be more extremely inclined objects in this group.

It remains uncertain why these six objects apparently cluster together. Astrophysicists Konstantin Batygin and Michael Brown at the California Institute of Technology in Pasadena recently found that they may have been scattered off-kilter from the rest of the solar system by the gravitational pull of "Planet Nine," a world about 10 times Earth's mass that may exist about 500 times farther away from the sun than Earth.

Another possible origin for this group is "galactic tides." As the sun orbits the center of the Milky Way, it moves up and down within the disk of the galaxy, and "tidal forces are exerted on the solar system that are thought in general to have a variety of effects, such as disturbing the Oort Cloud and throwing comets into the solar system," Payne said.

The scientists detailed their findings Oct. 17 at the American Astronomical Society Division for Planetary Sciences and European Planetary Science Congress in Pasadena, California.

Massive cloud on collision course with the Milky Way

In 1963, an astronomy student named Gail Smith working at an observatory in the Netherlands discovered something odd – a massive cloud of gas orbiting the Milky Way galaxy.

Smith’s cloud contained enough gas to make two million stars the size of our sun, and it was moving through space at 700,000 miles per hour.

For the next 40-plus years the cloud remained a curiosity, one of a growing number of so-called high velocity clouds circling the Milky Way – interesting but not sensational.

Then something changed.

In the mid-2000s, radio astronomer Jay Lockman and colleagues took a closer look at Smith’s Cloud using the Green Bank radio telescope in West Virginia, and they were able to calculate the cloud’s orbit.

Smith’s Cloud, it turns out, is on a collision course with the Milky Way.

Thirty million years from now, give or take a few million years, it will crash into the Perseus Arm of our galaxy. The impact will compress clouds of gas in that spiral arm, causing a brilliant burst of star formation.

There’s no real danger to the Milky Way. Smith’s Cloud is minuscule compared to the gigantic spiral of stars that makes up the backbone of our galaxy. But the coming collision has sharply increased interest in Smith’s Cloud.

“We don't fully understand the Smith Cloud's origin,” said Andrew Fox of the Space Telescope Science Institute. “There are two leading theories. One is that it was blown out of the Milky Way, perhaps by a cluster of supernova explosions. The other is that the Smith Cloud is an extragalactic object that has been captured by the Milky Way.”

To investigate these theories, Fox and colleagues recently peered into the cloud using the Hubble Space Telescope’s Cosmic Origins Spectrograph.

One of the elements they found was sulfur, absorbing ultraviolet light from the bright cores of three galaxies far beyond the cloud.

By analyzing the amount of light Smith’s Cloud absorbs, the astronomers were able to measure the abundance of sulfur in the cloud.

“The abundance of sulfur in Smith’s Cloud is similar to the abundance of sulfur in the outer disk of our own Milky Way,” Fox said.

This means we have a family relationship.

“The cloud appears to have been ejected from within the Milky Way and is now falling back,” Fox said. “The cloud is fragmenting and evaporating as it plows through a halo of diffuse gas surrounding our galaxy. It's basically falling apart. This means that not all of the material in Smith’s Cloud will survive to form new stars. But if it does survive, or some part of it does, it should produce an impressive burst of star formation.”

While Fox’s work has cleared up some of the mystery of the Smith Cloud, many questions remain: What calamitous event could have catapulted it from the Milky Way's disk, and how did it remain intact?

These are questions for future research. Thirty million years to impact: the clock is ticking!

Space FIREBALLS just found by NASA so fast they could get from moon to earth in 30 MINUTES

FIREBALLS are being blasted through space at such a speed they could travel from our Moon to earth in half an hour, it has emerged.

A NASA CGI of the solar blasts

The massive gas balls, which are twice as hot as the surface of our sun and twice the size of Mars, were detected by the Hubble telescope.

The mysterious plasma ejections were found being ejected near a dying star called V Hydrae.

A NASA spokesman said: "The plasma balls are zooming so fast through space it would take only 30 minutes for them to travel from Earth to the moon.

"This stellar "cannon fire" has continued once every 8.5 years for at least the past 400 years, astronomers estimate."

The fireballs have puzzled astronomers, because the ejected material could not have been shot out by host star V Hydrae, as this is a bloated dying red giant, 1,200 light-years away.

It has probably shed at least half of its mass into space during its death throes.

Red giants are dying stars in the late stages of life that are exhausting their nuclear fuel that makes them shine.

They have expanded in size and are shedding their outer layers into space.

The spokesman added: "The current best explanation suggests the plasma balls were launched by an unseen companion star.

This four-panel graphic illustrates how the binary-star system V Hydrae is launching balls of plasma into space.

Panel 1 shows the two stars orbiting each other. One of the stars is nearing the end of its life and has swelled in size, becoming a red giant.

In panel 2, the smaller star's orbit carries the star into the red giant's expanded atmosphere.

As the star moves through the atmosphere, it gobbles up material from the red giant, which settles into a disk around the star.

The buildup of material reaches a tipping point and is eventually ejected as blobs of hot plasma along the star's spin axis, shown in panel 3.

This ejection process is repeated every eight years, the time it takes for the orbiting star to make another pass through the bloated red giant's envelope, shown in panel 4.

"According to this theory, the companion would have to be in an elliptical orbit that carries it close to the red giant's puffed-up atmosphere every 8.5 years.

"As the companion enters the bloated star's outer atmosphere, it gobbles up material.

"This material then settles into a disk around the companion, and serves as the launching pad for blobs of plasma, which travel at roughly a half-million miles per hour."

This star system could be the archetype to explain a dazzling variety of glowing shapes uncovered by Hubble that are seen around dying stars, called planetary nebulae, researchers say.

A planetary nebula is an expanding shell of glowing gas expelled by a star late in its life.

Raghvendra Sahai of NASA's Jet Propulsion Laboratory in Pasadena, California, lead author of the study, said: "We knew this object had a high-speed outflow from previous data, but this is the first time we are seeing this process in action.

"We suggest that these gaseous blobs produced during this late phase of a star's life help make the structures seen in planetary nebulae.

"We want to identify the process that causes these amazing transformations from a puffed-up red giant to a beautiful, glowing planetary nebula.

"These dramatic changes occur over roughly 200 to 1,000 years, which is the blink of an eye in cosmic time."

Mr Sahai's team used Hubble's Space Telescope Imaging Spectrograph (STIS) to conduct observations of V Hydrae and its surrounding region over an 11-year period, first from 2002 to 2004, and then from 2011 to 2013.

Spectroscopy decodes light from an object, revealing information on its velocity, temperature, location, and motion.

The data showed a string of monstrous, super-hot blobs, each with a temperature of more than 17,000 degrees Fahrenheit - almost twice as hot as the surface of the sun.

Based on the observations, Mr Sahai and his colleagues Mark Morris of the University of California, Los Angeles, and Samantha Scibelli of the State University of New York at Stony Brook developed a model of a companion star with an accretion disk to explain the ejection process.

Mr Sahai said: "This model provides the most plausible explanation because we know that the engines that produce jets are accretion disks.

"Red giants don't have accretion disks, but many most likely have companion stars, which presumably have lower masses because they are evolving more slowly.

"The model we propose can help explain the presence of bipolar planetary nebulae, the presence of knotty jet-like structures in many of these objects, and even multipolar planetary nebulae. We think this model has very wide applicability."

The team's results appeared in the August 20, 2016, issue of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt.