solar system

How to Send Your Name to the Red Planet

Astronomy and Physics, News, solar system

Almost every child has dreamed of being an astronaut. We look up at the stars and wonder what’s up there. While not everyone will be an astronaut, there are other ways to get your name to space.

NASA has announced a public engagement campaign in which anyone can submit their name to be sent to Mars. The names will be etched onto a chip and sent with NASA’s Mars 2020 rover. The names will be written “smaller than one-thousandth the width of a human hair”, according to NASA.

So far, over 4 million names have been submitted. A single chip can hold over a million names, but I think it’s safe to assume that NASA will be sending more than one chip with the rover.

Everyone who submits their name will receive a “boarding pass” for a flight to Mars. This boarding pass is, of course, for fun, and not a ticket to the Red Planet. It also “awards” frequent flyer points.

Anyone who wants to submit their name has until the end of September to do so. To submit your name, click here.

The rover will launch in July/August 2020 because Mars and the Earth will be close to each other. When they’re closer together, it takes less fuel, time, and money to launch. Therefore, these “close approaches” are simply the best time to launch.

Artist concept of the Mars 2020 rover. Source: NASA/JPL-CalTech

This rover’s main research will be regarding potential life on Mars. The rover will drill into the Martian surface to collect rock and dirt samples. These samples will be set aside, potentially to be brought to Earth in the future. In addition, the rover will look for organic compounds in the rocks. Other functions include testing an oxygen-production method and looking for subsurface water.

NASA’s Mars 2020 rover is going to allow us to understand the Red Planet’s history as well as we understand the Earth’s. In addition, scientists are hoping to answer questions about the possibilities of humans residing on Mars. That goal, however, is a long way away. NASA has recently announced plans to land humans on the Moon by 2024. This is a huge step towards Mars, but the Moon is considerably closer than Mars. Right now, the plan is to land humans on Mars in the 2030s.

Slowly but surely, humanity is going to Mars. It’ll be an exciting thing to watch. Click here for more information on Mars 2020.

Saturn’s Spectacular Rings

Astronomy and Physics, solar system

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 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.

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