Saturn’s Spectacular Rings

Saturn’s rings are easily one of the most amazing sights in the solar system. However, most people don’t know much, if anything, about them. First, it’s important to note that Saturn is not the only planet with rings; all four gas giants have them! However, Saturn’s rings are bigger than any other planet’s. They’re big enough that they can be seen with a relatively small telescope from your own backyard!

Discovering the Rings

Galileo was the first to observe Saturn’s rings in 1610. However, he didn’t immediately realize that what he was looking at was rings. He described what he saw as “ears,” and drew a circle with a smaller circle on either side. Two years later, these “ears” disappeared completely from view. Even more confusing was when they reappeared in 1613.

Galileo’s drawing of Saturn. Top from 1610, bottom from 1616. Source: NASA

In 1655, Christiaan Huygens observed Saturn with a newer, more advanced telescope. He was the first to suggest that Galileo’s “ears” may, in fact, be a system of rings around the planet. Around the same time, Robert Hooke observed the rings and noticed shadows upon them. Then, in 1675, Giovanni Domenico Cassini (also known as Jean-Domenico Cassini) discovered a gap in the rings. Over 100 years later, in 1787, Pierre-Simon Laplace proved that a single disk would not be stable as rings, and proposed that the rings were many tiny rings. Then, over 70 years after that, in 1859, James Clerk Maxwell proved that rings had to be made of many tiny particles to be stable. Nearly 40 years later, in 1895, James Keeler of Allegheny Observatory and Aristarkh Belopolsky of Pulkovo Observatory confirmed that Maxwell was correct; the rings are made up of many tiny particles.

A Look at the Rings

There are 7 major rings around Saturn. Closest to the planet is the D ring, followed by the C ring, B ring, A ring, F ring, G ring, and finally, the E ring. The rings were named in the order they were discovered, so, unfortunately, there is nothing intuitive about this naming system. The rings are made of particles of water ice, ranging in size from .4 inches to 39 inches (1 centimeter to 10 meters). All of these bits added together are about half the size of the Earth’s Antarctic ice shelf.

The rings are roughly 180,000 miles (400,000 kilometers) wide but only 30 to 3280 feet (10 to 1000 meters) thick. The rings are so much wider than they are thick that the rings form a disk-like shape. In fact, if you were to make a scale model of Saturn’s rings in which their thickness is that of a sheet of paper, the rings would be 1.7 miles (2.7 kilometers) across.

Source: NASA/JPL-Caltech/Space Science Institute

Evidence suggests that the rings are only 100 million years old. 100 million years ago, dinosaurs were still wandering the Earth! Now, I know this seems old, but on the time scale of the solar system, that’s basically a baby! For reference, the Earth formed 4.5 billion years ago. That means that the rings formed 4.4 billion years after the Earth.

Scientists are not really sure how the rings formed, so there are a couple of different theories. Many of the theories propose that a moon may have been destroyed (whether by Saturn’s gravity or a collision with another object) and the debris formed the rings. Another theory is that the rings are just leftovers from Saturn’s formation that failed to form a moon. Saturn’s E ring, however, is formed in a totally different way. As Saturn’s moon Enceladus orbits the planet, it spews its icy innards into orbit.

Saturn’s rings are largely influenced by its moons. The Keeler Gap, a break in the A ring, is caused by Saturn’s moon Daphnis clearing its path around the planet. Prometheus and Pandora created the F ring, making them shepherd moons. A shepherd moon is a moon whose gravity forces material into a ring, like a shepherd with their sheep. There are other minor rings who have been corralled there by nearby moons.

Disappearing Rings

Every 15 years, Saturn’s rings grow thinner and thinner until finally, they disappear from view! This phenomenon is known as a ring plane crossing. Galileo was the first to observe a ring plane crossing in 1612 when the “ears” of Saturn disappeared. Like the Earth, Saturn and its rings are tilted with the Sun—27 degrees, to be exact. When the Earth and the rings line up just right, the rings are edge on to us. Since the rings are so thin, we can’t see them. The next ring plane crossing is on March 23, 2025, but Saturn will be close to the Sun and therefore difficult to view.

Left: Source: NASA and The Hubble Heritage Team (STScI/AURA)Acknowledgment: R.G. French (Wellesley College), J. Cuzzi (NASA/Ames), L. Dones (SwRI), and J. Lissauer (NASA/Ames). Right: Saturn with two of it’s moons, only visible during a ring plane crossing. Source: Amanda S. Bosh (Lowell Observatory), Andrew S. Rivkin (Univ. of Arizona/LPL), the HST High Speed Photometer Instrument Team (R.C. Bless, PI), and NASA/ESA.

Ring plane crossings are very exciting for astronomers because it gives them an opportunity to view the planet without the giant, bright rings in the way. In addition, many of Saturn’s moons can only be viewed during a ring plane crossing. 13 of Saturn’s moons were discovered during ring plane crossings, while others’ orbits were able to be studied further. Furthermore, scientists can discover more rings during the crossing—that’s how they found the E ring.

One thing that scientists know for sure is that Saturn’s rings used to be bigger than they are now. They know this because the rings fall into Saturn and become what is appropriately called “ring rain.” At the rate at which the rings are decaying, they could disappear as soon as 100 million years from now.

Luckily, 100 million years is plenty of time for us humans, and we have a lot more research to do. The Cassini spacecraft was able to answer some questions for us, but not all. Saturn’s beautiful rings may not last forever—but they’ll last a lifetime. And that, my friends, is enough for me.

Best Moons in our Solar System

Astronomy and Physics, solar system

In our solar system, there are nearly 200 moons orbiting eight different planets. Of course, these moons aren’t split evenly. Mercury and Venus don’t have any moons, while Jupiter has over 70—and counting. With this many moons, it’s easy to pick favorites. So I did! Here are six of my favorite moons in the solar system.

Our moon

Left: From Bill Ingalls. Top Right: Apollo 8’s iconic Earthrise, taken by Bill Anders. Bottom Right: The moon, as viewed from Earth, with Venus to the left. From Bill Dunford. Source: NASA

Naturally, I have to start with our moon, sometimes called Luna. Our Moon has a radius of 1080 miles (1737.5 kilometers) and is 238,855 miles (384,400 kilometers) from the Earth. With roughly the same apparent size as the Sun, the moon is the brightest object in our night sky. The Moon is tidally locked with the Earth, meaning we always see the same side of the Moon. The side we don’t see is often called “the dark side of the Moon,” but this is simply not true. This side of the Moon is lit by the Sun just as often as the other side.

The Moon is the only place outside of the Earth that humans have been. Thanks to this, we know tons about the Moon. For example, we know that the Moon has no atmosphere, and therefore, no wind. In addition, we have a pretty good map of the Moon and its craters. These craters are the most prominent features on the Moon’s surface.

Mimas

Left: Taken by the Cassini spacecraft. Top Right: Saturn with Mimas, a tiny dot to the bottom left of the image. Taken by the Cassini spacecraft. Bottom Right: Taken by Voyager 1. Source: NASA/JPL

Mimas just might be my favorite moon in the solar system. Discovered orbiting Saturn by William Herschel in 1789, it’s most prominent feature is the giant crater (complete with a central peak) on the right side of the image. This crater is named Herschel, after, of course, the man who discovered the moon. In the 1980s, NASA got its first up-close images of the moon as the Voyager crafts passed by. Immediately, many Star Wars fans noticed that Mimas looks an awful lot like the Death Star! Years later, the Cassini spacecraft took more fantastic images of the moon.

Mimas is one of Saturn’s closer moons, orbiting only 115,000 miles (186,000 kilometers) from the planet. Like our moon, Mimas is tidally locked with Saturn. Mimas is slightly ovoid (meaning a little more oval than a sphere, like an egg) and has a mean radius of 123 miles (198 kilometers). In addition, Mimas seems to be made entirely of water ice.

Io

Top Left: An eruption can be seen as a blue haze on top of the planet. Taken by the Galileo spacecraft. Bottom Left: A tiny Io is dwarfed by Jupiter. Right: Io, in true color. Source: NASA/JPL/University of Arizona

In 1610, Galileo pointed his telescope towards Jupiter and noticed four little dots moving back and forth across the planet. These four dots are now known as the Galilean Moons, my favorite of which is Io. Only a little larger than our moon, Io shoots around Jupiter in less than two Earth days at a distance of 262,000 miles (422,000 kilometers). As Io speeds around Jupiter and through its electric field, the moon generates a current that sparks lightning in the planet’s upper atmosphere.

Io’s weird, dotted color (making it look a little like a moldy pizza) is due to the volcanoes that cover the moon. In fact, Io is the most volcanically active body in the solar system. Like Mimas and our moon, Io is tidally locked with Jupiter. This, along with its highly elliptical orbit, cause insane tidal forces on the moon. These forces heat up Io, causing all the volcanic activity. Io seems to be made of mostly sulfur or silicate rock. These materials would explain Io’s “moldy pizza” appearance.

Phobos and Deimos

Top Left: Phobos. Bottom Left: Deimos. Right: Mars with the two moons as seen by Curiosity. Source: NASA/JPL-Caltech/GSFC/Univ. of Arizona

Deimos and Phobos were discovered by Asaph Hall in 1877. These cratered, irregularly shaped moons are among the smallest in the solar system. Right now, it’s believed that these moons are captured asteroids, but it’s possible that this is untrue. Like many other moons, these are tidally locked with Mars.

Phobos, the larger of the two, speeds around Mars three times a day. This moon is gradually moving closer to the planet, meaning that in the future, it will either crash into Mars or break apart into rings. A prominent feature of Phobos is the giant impact crater, called Stickney. Stickney is 6 miles (9.7 kilometers) wide.

Deimos only orbits Mars once every 30 hours. Deimos appears to be so tiny that it’s gravitational pull can’t hold onto ejected material after a meteorite strikes.

Titan

Left: The first image of Titan’s surface, taken by the ESA’s Huygens probe. Top Right: Titan and Diane (another of Saturn’s moons) in front of the Planet. Taken by Cassini. Bottom Right: Titan in front of Tethys (another of Saturn’s moons). Taken by Cassini. Source: NASA/JPL/ESA/University of Arizona

Titan has a radius of 1,600 miles (2,575 kilometers) and orbits Saturn once every 16 Earth days. Titan is Saturn’s largest moon, and the only moon known to have a significant atmosphere. This atmosphere, made of nitrogen, gives Titan it’s hazy appearance. Titan rains methane and ethane onto a water ice crust. Seas, lakes, and rivers, also made of methane and ethane, flow across the surface. Beneath the crust is a sea of water.

Titan’s water interior could hold life. Even more exciting, however, is the possibility of the surface holding life. Life that formed on Titan’s surface would be chemically different from our own. That being said, there is currently no evidence of Titan containing life; more research is needed.

Europa

Top Left: Taken by the Galileo spacecraft. Bottom Left: Europa’s scratched surface, taken by the Galileo spacecraft. Right: Jupiter with Europa to the right, casting a shadow on the planet. Source NASA/JPL-Caltech/SETI Institute/ASU

Europa, another Galilean moon, is largely considered to be the best shot at life off of Earth. Europa has a diameter of 1,940 miles (3,100 kilometers) and orbits Jupiter twice every seven Earth days. Europa’s surface is made of water ice with a deep liquid water ocean underneath. This icy surface is covered with scratches and cracks due to tidal forces from Jupiter, Io, and Ganymede. These tidal forces also heat up Europa’s subsurface sea.

Like Io, Europa also has an induced magnetic field from Jupiter’s magnetic field. The fact that there is a magnetic field suggests a salt water ocean under the icy surface. We know that life could potentially form there because life has formed in similar conditions on Earth. Right now, missions are being planned by NASA and the ESA (European Space Agency) to find life on Europa.

All the data in the article came from NASA.

The Station in the Sky

Astronomy and Physics, Earth

In October 2000, the International Space Station (ISS) received its first-ever crew. Russians Sergei K. Krikalev and Yuri Pavlovich Gidzenko and American William M. Shepherd flew to the ISS on Halloween and stayed there until March 21, 2001.

Official Photo of the Expedition One crew. Left to Right: Sergei Krikalev, William Shepherd, and Yuri Gidzenko. Source: nasa.gov

This mission was a long time in the making. Sixteen years before, President Ronald Reagan had instructed NASA (the National Aeronautics and Space Administration) to build a space station that would orbit the Earth for years to come. In the 1990s, the United States and Russia decided to combine their separate efforts and build one space station. Thus, the ISS was born.

Construction of the ISS didn’t officially begin until 1998 when Russia and the United States each sent up a piece of the station. These pieces were then connected by American astronauts. In the following years, more and more pieces were added. Today, the ISS is about as large as an American football field!

In addition to the U.S. and Russia, 13 other countries have joined the effort. Spanning at least three continents, the ISS is one of the few truly world-wide efforts. Canada, Japan, and many European countries work together to keep the ISS running smoothly every day.

This graphic shows the true international nature of the ISS. Source: nasa.gov

Orbiting 250 miles (about 402 kilometers) above the Earth, the ISS travels at a speed of 17136 miles per hour (7.66 kilometers per second). This speed means that the ISS completes an orbit of the Earth every 92 minutes, or about 15.5 per day.

The ISS Today

Today’s ISS crew consists of Americans Anne McClain, Nick Hague, and Christina Koch, Russians Commander Oleg Kononenko and Alexey Ovchinin, and Canadian David Saint-Jacques.

Official Expedition 59 Crew Portrait: Oleg Konenenko, David Saint-Jacques, Anne McClain, Oleg Shkripochka and Christina Koch. Source: nasa.gov

Aboard the ISS, the crew conducts experiments in space’s zero-gravity environment. According to the ISS’ U.S. Laboratory website, the ISS has four main areas of research: Life Sciences, Physical Sciences, Remote Sensing, and Technology Development.

Life Sciences

The main thing scientists study is how different organisms react to the zero-gravity in space. One experiment that is often done is the growth three-dimensional cell cultures. On Earth, cell cultures are grown flat on the bottom of Petri dishes. In space, these cells can grow any way they want, which better reflects how the cells would grow in a body.

Another aspect that is studied is how a microgravity environment affects the human body. For example, astronauts often experience muscle decay while in space. Researching this and other changing body functions could offer insight into better ways to treat and prevent similar conditions on Earth.

Physical Sciences

One interesting deviation from Earth-like physics that is studied on the ISS is fluid dynamics. Fluid dynamics is the physics of how fluids move. On Earth, gravity often overpowers any other fluid movement. However, in space, the fluids are free to flow without the influence of gravity. Fluid dynamics is not fully understood, and its influence is everywhere from pharmaceuticals to energy conservation efforts.

In addition, the scientists aboard the ISS often test out new materials. The extreme conditions of space are the perfect place to perform these experiments because it is easier to control the environment in which the experiment takes place. Testing on the ISS is faster, cheaper, and gives better quality results than testing on Earth.

Remote Sensing

On the ISS, astronauts have a much better vantage point that we have on Earth. Their bird’s eye view is extremely helpful in many different areas as it is quite easy to watch over the Earth from space. For example, ISS images are often used during disaster response situations. In addition, the ISS tracks ships on the ocean, as well as land use. Furthermore, scientists can see how large coral reefs, glaciers, and other environmental landmarks are from space.

Another huge benefit of the ISS is that it can look into space without the atmosphere in the way. On Earth, the atmosphere distorts the light coming from distant stars. In space, this limitation is eliminated. In addition, many portions of the electromagnetic spectrum are absorbed by the atmosphere. If an object in space emits light in this portion of the spectrum, we don’t see it on Earth. In space, we can see the entire spectrum, so we can receive more data.

Technology Development

On the ISS, they often test different functions of new satellites. This is ideal because these tests are performed in the environment where the finished product will need to perform these functions. In addition, the ISS is crucial for helping develop communication technology. This is important not only for space travel but also for Earth communications.

Education on the ISS

NASA and the ISS have many education initiatives including opportunities for students to be involved with research. For example, students can design an experiment for the ISS through the Student Spaceflight Experiments Program. What’s more, the ISS often performs what they call “STEMonstrations”, that is, STEM (Science, Technology, Engineering, and Mathematics) demonstrations. These provide an opportunity for students to see what happens on the space station.

The ISS is a symbol of international cooperation as countries band together for the pursuit of knowledge. The space station is rocketing humanity forward as scientists on board answer questions that simply can’t be answered on Earth.

For more information about the International Space Station and its missions, visit NASA or the ISS’ U.S. National Laboratory.

The Plight of Pluto

Astronomy and Physics, solar system

Ah, Pluto. Everyone’s favorite (dwarf) planet. For some reason unbeknownst to the general public, scientists stripped Pluto of its planetary status in 2006. Many Millennials seem to feel personally attacked for this demotion. They dramatically claim that losing Pluto is like losing a member of our interplanetary family.

Unfortunately, scientists are right. Pluto is not a planet.

Discovering Pluto

In the 1840s, scientists noticed that Uranus’ orbit was inconsistent with predictions from the physics they knew of at that time. Using math, they concluded that another planet must be out there. Scientists pointed their telescopes to the sky and found Neptune. Even after finding Neptune, many felt that another planet must be out there because Neptune didn’t seem to solve all the problems with Uranus’ orbit. Since it had worked once before, they once again pointed their telescopes to the stars. And they found something.

The arrow points to a dot that moves separately from the background stars. This dot is Pluto. From the Lowell Observatory.

Scientists noticed something that was not a far away star—something close. Something orbiting the Sun. They assumed they had found a new planet because astronomers didn’t yet understand the structure of our solar system. They thought that Pluto was much larger and much farther away. However, as time went by, they calculated an increasing small mass for Pluto.

Eventually, astronomers realized the calculations that led to Pluto’s discovery were wrong. There were no problems with Uranus’ orbit. And even if there was, Pluto’s tiny mass wouldn’t account for this difference.

As time went by, astronomers found more Pluto-like objects in the outer solar system, including Eris. A dwarf planet discovered in 2003, Eris is more massive than Pluto (although a little smaller). This forced astronomers to re-evaluate their definition of a planet.

Defining a Planet

In 2006, scientists gathered at The International Astronomy Union’s General Assembly and tackled the question plaguing astronomy at the time: what defines a planet? They decided that a planet must do three things:

1. Orbit a star.

Pluto does this. Check.

2. Be massive enough to hold itself together in a round shape.

Pluto does this too. Check.

3. Dominate its neighborhood.

Pluto does NOT do this. Pluto lies in a portion of the solar system known as the Kuiper Belt, a region that contains small icy bodies, like a second asteroid belt.

Pluto’s orbit, seen in yellow, goes right through the Kuiper Belt. The planets’ orbits, which are white, each trace out their own area. Source: nasa.gov

To be fair, Pluto is a fairly large object for it part of the Solar System; it’s the second most massive non-planet orbiting the Sun. That being said, some moons are larger than Pluto. Looking at the image above, Pluto definitively does not dominate its neighborhood. Scientists ultimately demoted Pluto (and Eris) to a “dwarf planet.”

More evidence

Tilt with the ecliptic

All eight of our planets lie within the same plane of the solar system called the ecliptic plane. However, Pluto is 17 degrees off of this plane. The only other planet to be off the ecliptic is Mercury, but this difference is easily explained by General Relativity. So the question remains: how did Pluto get off the ecliptic?

Pluto’s orbit is vary different from the others. Source: nasa.gov

One theory is that Pluto may have collided with another object, knocking it out of the plane. Another theory is that Pluto may be a captured satellite from a different solar system. Either way, this orbital tilt is very weird for a planet, but quite normal for a Kuiper Belt object.

Charon and Pluto

Another damning piece of evidence comes from Pluto’s moon, Charon. Charon’s mass is about one-eighth of Pluto’s mass, which is relatively large for a moon. For comparison, our moon is only 1.2 percent of the Earth’s mass. This giant moon doesn’t actually orbit Pluto; instead, Pluto and Charon orbit a spot in between them, outside of either body.

Charon, on the left, is quite large for a moon. Pluto, on the right, is the object that Charon Orbits. Taken by the New Horizons Spacecraft. Source: nasa.gov

Some feel that Charon and Pluto should be considered a binary system. However, Charon’s official classification is one of Pluto’s Satellites.

It is important to note that Pluto’s moons don’t make it a planet. 87 Pluto-like objects are also known to have moons. Also, not all planets have moons; Mercury and Venus don’t.

Sorry folks, Pluto is not a planet

When you look at all the evidence, it’s clear that Pluto isn’t a planet. Pluto was only considered a planet because we didn’t know what our solar system looked like. Once we learned more, we needed to reclassify certain objects. That’s what science is all about—learning and adapting.

Pluto didn’t change, it’s official classification did. This, of course, doesn’t mean that we should forget about Pluto. There is still much Pluto can tell us about our solar system; that’s why scientists continue to study the dwarf planet. However, to say that Pluto is as important in the solar system as the planets is completely false. Regardless of what we call it, Pluto is undoubtedly one of the most loved objects in the solar system.

Check out my other recent posts below!

A Brief Introduction to Black Holes

Astronomy and Physics, Beyond

On April 10, 2019, astronomers released the first-ever image of a black hole. This image depicts a supermassive black hole in the center of a giant elliptical galaxy known as M87. This image is incredibly important because black holes have never been seen before because they’re, well, black. Black holes do not emit any light (like stars do), nor do they reflect light (light the moon does). This makes them notoriously difficult to detect. In fact, black holes were purely theoretical until the detection of gravitational waves in 2015.

What Are Black Holes?

Black holes were first theorized in the 18th century, but they weren’t truly predicted until 1915 when Einstein published his theory of general relativity. Black holes are a natural prediction of this theory, which simply states that mass bends the four-dimensional spacetime. Not long after, Karl Schwarzschild solved Einstein’s equations and found that for an infinitesimally small point mass, the equations break down when you get near the point mass. This means that physics stops working once you get too close to a black hole. The distance at which physics breaks down is known as the Schwarzschild radius. This radius forms a spherical surface known as the event horizon.

Black holes are an example of extreme physics that form after a massive star dies. This star collapses in on itself and doesn’t stop until the mass is concentrated at an infinitesimally small point in space. This forms a gravitational well so deep that nothing—not even light—can escape. This has one main consequence: we can’t see black holes. What’s more, there didn’t seem to be any way that we could even prove they existed. However, in 2015, scientists had the first physical proof of black holes via gravitational waves. Gravitational waves radiate from high energy collisions. Detectors found evidence of such a collision between two supermassive black holes. Now, for the first time ever, we see a black hole.

Seeing Black Holes

The image shows the black hole in the center of M87, a massive elliptical galaxy. Scientists knew that this galaxy contained an active black hole because of the blue jet seen in the image below.

M87, with a blue jet extending to the bottom right corner. Source: nasa.gov

Scientists used a collaboration of radio telescopes across the globe to see the black hole. They took so much data from their observations that it couldn’t be shared over the internet; they had to manually take the hard drives to one location. After observing the black hole in 2017, it took them two years to compile the data into a single image.

When looking at the image released by the New Horizons Telescope, seen below, one can see a red ring around a dark center. This dark center is the event horizon of the black hole—the point of no return. The red ring is hot, energized, glowing gas. This gas is glowing because it is being flung around the black hole, heating it up. Furthermore, the gas is brighter at the bottom of the image because there, the gas that is moving towards us.

The picture of the black hole taken by the New Horizons Telescope.

Even today, there are tons that we don’t know about black holes. We don’t know how the supermassive black holes in the center of galaxies formed. We don’t know what happens to the information pulled into black holes. We don’t even know how many black holes there are. To say the least, there is a lot of research about black holes coming. Who knows what secrets they keep to themselves. Maybe one day, we’ll find out. Until that day, astronomers will keep on searching the stars for answers.