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A Trip into the Life of Sally Ride

Astronomy and Physics, Earth, News, women in science

Sally Ride was born on May 26, 1951, in Los Angeles, California. She went to a private high school on a scholarship, where she was a bright student and an excellent tennis player. Ride first attended Swarthmore College in Pennsylvania but ultimately graduated from Standford where she majored in physics and English. She went on to earn her Ph.D. from Standford in 1978. There, Ride studied x-rays emitted by stars. 

In 1978, Dr. Ride applied to be an astronaut after seeing an ad in the school newspaper. She was among the first six women to be selected and had to go through intense training. Ride was not a pilot, but she still had to spend time in a plane—just not in the pilot’s seat. Instead, she trained by being the navigator and communicator for the pilot. Ride loved her time in the plane. In fact, she loved it so much that she later got her pilot’s license. Before going to space, Ride worked in Mission Control. There, she was capsule communicator (CAPCOM for short), which serves as the link from ground to space. NASA prefers astronauts at CAPCOM because they know all the astronauts’ slang.

Source: NASA

Unfortunately, as a female astronaut, Ride faced lots of sexism. People were not used to seeing a woman in such a role. Members of the media often asked Ride extremely sexist questions they would never ask her male colleagues. She was asked “Will the flight affect your reproductive organs?” and “Do you weep when things go wrong on the job?” Luckily, Dr. Sally Ride never let the ignorance of the media stop her. 

Finally, in 1983, Ride became the first American woman in space. Ride flew on the space shuttle Challenger, and successfully completed her mission with her crew. On the shuttle, Ride operated a robotic arm that put satellites into space. Two of these satellites were simply communication satellites, but another carried experiments. Then, in 1984, she went to space again, also aboard the Challenger. She was training for a third mission when the Challenger Disaster occurred. Her mission was canceled, and she would never go to space again. In total, Dr. Sally Ride spent 14 days, 7 hours, and 46 minutes in space. 

The thing that I’ll remember most about the flight is that it was fun. In fact, I’m sure it was the most fun I’ll ever have in my life.

Sally Ride

Ride was selected to the Rogers Commission, which investigated the Challenger explosion. She was instrumental in discovering the cause of the disaster. In 2003, she was asked to help investigate the Columbia accident. She is the only person to serve on commissions for both accidents. 

In 1987, Ride left NASA to work at the Stanford University Center for International Security and Arms Control. They educate tomorrow’s leaders of international policy, while also influencing today’s policy. Just two years later, she became a physics professor at the University of California, San Diego. In the 90s, she led NASA outreach programs that allowed students to ask for images of the Moon and Earth. She co-founded Sally Ride Science in 2001, a company that focuses on encouraging students, especially girls, to get into science. There are so many aspects of science that aren’t well known, so Sally Ride Science shows kids what futures lie in science. This non-profit thrives to this day.

Sally Ride Science. Source: NASA

On July 23, 2012, Dr. Sally Ride died. She had pancreatic cancer, one of the most deadly cancers. After her death, it became known that she had a female partner. She had a husband while she was an astronaut, but the marriage quickly ended in divorce. Sally Ride and Tam O’Shaughnessy had been partners for the 27 years prior to Ride’s death. Ride had been very private with her personal life, so the public was unaware of this. Ride is the first known LGBT astronaut. 

Sally Ride continues to be an inspiration to this day. She blended science with humanities as an undergrad. She serves as a role model for both young girls and LGBT youth as her legacy lives on through Sally Ride Science. She is the epitome of strength and perseverance, and I look to her when I find myself faced with sexism. We will never forget Sally Ride. Dr. Sally Ride ensured that the world she left behind was better than when she came. We can all learn a lesson from her.

To read more about Women in Science, check out the links below:

Nancy Grace Roman: the Mother of Hubble

Astronomy and Physics, Earth, News, women in science

Dr. Nancy Grace Roman was interested in astronomy from the very beginning. Born in Tenessee in 1925, in elementary school Roman was a co-founder of an astronomy club. She went on to excel in a Baltimore high school and attended Swarthmore College to earn her bachelors degree in Astronomy. In 1949, she received her doctorate in astronomy from the University of Chicago.

Dr. Roman in 1962. Credit: NASA

Shortly after earning her Ph.D., Dr. Roman found a star with unusual emission spectra. This discovery helped her create a name for herself among astronomers.

She began her work teaching at the University of Chicago but left because she didn’t see a future for herself there. She believed that she would never receive tenure simply because she was a woman.

I’m happy about the fact that women can get senior jobs now. They’re not being quite as discouraged as I was.

Nancy Grace Roman

In 1959, Dr. Roman became NASA’s first chief of astronomy. She traveled across the country, speaking to astronomers and giving lectures. She spoke of the advantage of observing the stars from outer space: no light pollution, no clouds, and no atmosphere to block parts of the signal. Most importantly, however, she spoke about and lobbied for the Hubble Space Telescope.

Dr. Roman spoke to secure funding for the project. She pushed for designs to be drawn. Her work has earned her the title “the Mother of Hubble.” And yet, very few people have heard of her.

It wouldn’t be until 1990, after her retirement, that she would see her efforts launched into orbit. 

Nancy Grace Roman, later in life. Source: NASA

Dr. Nancy Grace Roman died in 2018 at the age of 93. A fantastic scientist, inspirational woman, and passionate person, her legacy lives on in our beloved Hubble Space Telescope.

Dr. Roman did everything she could to help the Hubble Space Telescope project. Who knows where it would have gone without her? But Dr. Roman is largely forgotten. Time is washing her memory into oblivion. We must keep Dr. Roman and every other influential woman in history alive. I, among others, must write about her. You must talk about her. We must remember her.

To read about more women in science, check out the links below:

Seeing Distant Planets

Astronomy and Physics, Beyond, News

As always, the Hubble Space Telescope is looking to the stars for new exciting sights. Images of swirling galaxies are extremely common. On June 3, 2019, the Hubble Space Telescope released this photo of two exoplanets orbiting a distant star―an incredibly uncommon sight.

The system is called PDS 70 and is located in the constellation Centaurus. Less massive but larger than our sun, the star, also called V1032 Centauri, is a K5 type. K5 stars are cooler and dimmer than our sun. PDS 70 is 370 light-years from the Earth. That’s over 2.17 quadrillion (2,170,000,000,000,000) miles (3.5 quadrillion kilometers)!

In the image below, the white star represents the location of V1032 Centauri. To the left is PDS 70 b and to the right is PDS 70 c.

Exoplanets PDS 70 b and c. Source: ESO and S. Haffert (Leiden Observatory)

Right now, the only way astronomers know how to find planets is by observing the light from the stars. If there is a regular periodic dip in the signal, astronomers can infer that something is passing in front of it. Anything large enough to do this is probably a planet. While this is helpful, a measurement taken from this far leaves lots of room for error.

These planets were first imaged using the Very Large Telescope in Chile. We know that PDS 70 b is 4 to 17 times as massive as Jupiter, while PDS 70 c is 1 to 10 times as massive. The large range in these estimates is a consequence of the lack of precision in the measurement.

Astronomers are rarely able to get images like this because the stars are so big and bright and the planets are small and dim. Star light completely conceals anything coming from a distant planet. In the image above, astronomers cancelled light from the star to reveal the planets.

Once again, the Hubble Space Telescope dazzles us with the cosmos. We will have to wait to see what new sights they excite us with next time!

Who is Killing the Earth?

environment, News

It is an indisputable fact that the Earth is getting warmer. Study after study after study has proven time and time again that temperatures are rising at an alarming rate. Glaciers are melting, sea levels are rising, and creatures everywhere are losing their homes to human growth. 97 percent of climate scientists agree that there is a problem. We cannot ignore this any longer.

Every day we see articles giving advice on how you, the average citizen, can stop global warming. If we all do our part, they claim, it will make a huge difference.

It’s time to stop pretending that the average citizen is to blame for this record level pollution. Only 100 companies produce 71 percent of global greenhouse gas emissions, according to the 2017 Carbon Majors Report. Most of these companies are fossil fuels producers.

Starbucks has started to phase out straws, but the new straw-less lids use more plastic than the straws and old lids did. These lids are recyclable, which is an improvement, but only if they get recycled. Statistically speaking, they won’t be. Only 9.5 percent of plastic is recycled. Over 75 percent ends up in landfills. According to the New York Times, Memphis’ airport (which has three Starbucks) has recycling bins, but everything placed in them goes to the landfill with the trash. Furthermore, an ocean clean up project found that 65 percent of plastic products cleaned up were from Coca Cola, Pepsi, or Nestle.

We blame residents for not recycling when many areas don’t pick up recycling. According to a 2016 report from The Recycling Partnership, only 53 percent of the United States has automatic access to curbside recycling. Curbside recycling is when it gets picked up from your house, the way garbage does. Without curbside recycling, residents have to take their recycling to a facility, sometimes across town. Many people don’t want to put this kind of effort in.

Alternatively, residents may pay for a private collector to pick up their recyclables. However, this could cost anywhere from $5 to $25 a month. In addition, fees could be added if you have more than one bin. Some may not be able to afford this, while others simply don’t care enough to pay for such a service.  

The government must lead the way to save our planet. Many are trying. Nearly 200 counties signed the Paris Climate Agreement, an agreement to make plans to cut emissions. In 2017, President Donald Trump pulled the United States out, despite overwhelming nation-wide support for the agreement.

Source: Marlon, J.R., Fine, E., and Leiserowitz, A. (2017). A majority of Americans in every state say the U.S. should participate in the Paris Climate Agreement. Yale University. New Haven, CT: Yale Program on Climate Change Communication.

That being said, even in the countries that are still a part of the agreement, goals are not being met. Furthermore, an article posted in Nature claims that the goals set by member nations are not enough to save the planet. But the Paris agreement is not binding. Nothing is stopping any country from not doing its part.

We, as humans, have to make a change. I want to see a world that future generations can thrive in, and not one plagued by extreme weather, decreased biodiversity, and rising sea levels that consumes the land we live on. Rejecting science and ignoring evidence will kill the Earth if we’re not careful.

So please, be careful.

For more information, review the sources below.

Another Galaxy Coming to Space Near You!

Astronomy and Physics, Beyond, News

Space continues to dazzle the eye! NASA recently posted this photo of Messier 90. Messier 90, also called NGC 4569, is a spiral galaxy located in the constellation Virgo about 90 million light years away from the Earth.

This image is a composite of light from the infrared, visible, and ultraviolet parts of the spectrum. The black portion of the photo is just a consequence of the camera used.

Source: ESA/Hubble & NASA, W. Sargent et al.

The most fascinating thing about Messier 90 is that the galaxy is moving towards us.

Most galaxies are moving away from us, with a few notable exceptions, including the Andromeda Galaxy. The galaxies move away because the universe is expanding. On a larger scale, everything moves away from us. However, on a more local scale, this expansion isn’t as intense, so galaxies are able to move towards one another.

Astronomers know Messier 90 is moving towards us because it is blue-shifted. The stars that make up galaxies produce photons, the particles of light, in every wavelength of the electromagnetic spectrum. When photons interact with atoms, such as the hydrogen and helium in stars, certain wavelengths are “blacked out” from the spectrum in what are called absorption lines. Absorption lines always occur at the same wavelength for each specific element. Therefore, scientists know exactly where the lines should be. Furthermore, they know exactly which elements a star contains based on these lines alone.

As a source moves towards the observer, the light waves are compressed, making them appear shorter. This causes the absorption lines to move to the shorter wavelength part of the spectrum, or towards the blue part of the visible spectrum. This is why we call them blue-shifted.

The same thing happens when galaxies move away, but instead, the wavelengths get longer. We call this red-shifted. In fact, the large number of red-shifted galaxies is how Edwin Hubble discovered the universe is expanding!

Messier 90 is a member of the Virgo Cluster, a neighbor of our own Local Group. The Virgo Cluster is another small cluster in our supercluster. The Virgo Cluster is thought to be whipping member galaxies around, causing some to be heading towards us. Astronomers think this because Messier 90 is not the only blue-shifted galaxy in the Virgo Cluster. Messier 86 is also blue-shifted!

Messier 90’s center has lots of active star formation, but this does not extend to the edges of the galaxy. Astronomers believe that this is another consequence of the galaxy’s membership in the Virgo Cluster. They theorize that other galaxies in the cluster have stripped Messier 90 of its interstellar material, quenching star formation. In addition, scientists believe that supernovae in the center of the galaxy blew star-forming material out of the galaxy.

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.

Illu-moon-ating Research

Astronomy and Physics, Earth, News

In 2020, NASA will be launching the Space Launch System’s first Exploration Mission. On board will be yeast (to study radiation in space), a solar sail (that will study a near-Earth asteroid), and something called Lunar Flashlight.

Many craters on the Moon are constantly shrouded in shadows. This is a huge problem because light is the only thing we receive from space that we can study (besides meteorites and, of course, going there). Since we don’t receive light from these craters, we have absolutely no idea what’s down there.

That’s exactly what Lunar Flashlight hopes to illuminate.

In the past, the only way to study shadowed craters was to slam something into them and study the debris that flies up. This method allowed scientists to study only one location at a time. Now, the whole Moon can be observed from orbit. Lunar Flashlight will use a solar sail to reflect light into these dark craters. Then, scientists will study the light reflected back and make a map of where the water ice is located.

Artist concept of Lunar Flashlight. Source: NASA/JPL-CalTech

We’ve known about water on the Moon since 2009 when NASA’s LCROSS probe slammed into the Moon’s south pole. Then, in 2017, researhers from Brown University made a map of water on the Moon. However, they acknowledge “that only a small fraction of the Moon has been directly sampled.” Lunar Flashlight hopes to fill in those gaps.

When we go back to the Moon, we want to do so in a strategic location. According to NASA, “resources at destinations in space, such as atmospheres, water ice and regolith, can be broken down into their component molecules and used as building materials, propellant, oxygen for humans to breathe and drinking water.”

Locations with more of these resources are therefore more valuable than those without. NASA hopes to find more of these locations in places that we have been unable to study. In the future, they may be used as a landing spot or the home of a Lunar base.

Nearly 50 years ago, NASA only dreamed of going to the Moon. Now, we are planning a Lunar base to take us beyond our tiny portion of the solar system. Lunar Flashlight is just the beginning.

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.