Solar System: Things to Know This Week

Our solar system is a jewel box filled with a glittering variety of beautiful worlds–and not all of them are planets. This week, we present our solar system’s most marvelous moons.

1. Weird Weather: Titan

Saturn’s hazy moon Titan is larger than Mercury, but its size is not the only way it’s like a planet. Titan has a thick atmosphere, complete with its own “water cycle” – except that it’s way too cold on Titan for liquid water. Instead, rains of liquid hydrocarbons like ethane and methane fall onto icy mountains, run into rivers, and gather into great seas. Our Cassini spacecraft mapped the methane seas with radar, and its cameras even caught a glimpse of sunlight reflecting off the seas’ surface. Learn more about Titan:

2. Icy Giant: Ganymede

Jupiter’s moon Ganymede is the largest in the solar system. It’s bigger than Mercury and Pluto, and three-quarters the size of Mars. It’s also the only moon known to have its own magnetic field. Details:

3. Retrograde Rebel: Triton

Triton is Neptune’s largest moon, and the only one in the solar system to orbit in the opposite direction of its planet’s rotation, a retrograde orbit. It may have been captured from the Kuiper Belt, where Pluto orbits. Despite the frigid temperatures there, Triton has cryovolcanic activity – frozen nitrogen sometimes sublimates directly to gas and erupts from geysers on the surface. More on Triton:

4. Cold Faithful: Enceladus

The most famous geysers in our solar system (outside of those on Earth) belong to Saturn’s moon Enceladus. It’s a small, icy body, but Cassini revealed this world to be one of the solar system’s most scientifically interesting destinations. Geyser-like jets spew water vapor and ice particles from an underground ocean beneath the icy crust of Enceladus. With its global ocean, unique chemistry and internal heat, Enceladus has become a promising lead in our search for worlds where life could exist. Get the details:

5. Volcano World: Io

Jupiter’s moon Io is subjected to tremendous gravitational forces that cause its surface to bulge up and down by as much as 330 feet (100 m). The result? Io is the most volcanically active body in the Solar System, with hundreds of volcanoes, some erupting lava fountains dozens of miles high. More on Io’s volcanoes:

6. Yin and Yang Moon: Iapetus

When Giovanni Cassini discovered Iapetus in 1671, he observed that one side of this moon of Saturn was bright and the other dark. He noted that he could only see Iapetus on the west side of Saturn, and correctly concluded that Iapetus had one side much darker than the other side. Why? Three centuries later, the Cassini spacecraft solved the puzzle. Dark, reddish dust in Iapetus’s orbital path is swept up and lands on the leading face of the moon. The dark areas absorb energy and become warmer, while uncontaminated areas remain cooler. Learn more:

7. A Double World: Charon and Pluto

At half the size of Pluto, Charon is the largest of Pluto’s moons and the largest known satellite relative to its parent body. The moon is so big compared to Pluto that Pluto and Charon are sometimes referred to as a double planet system. Charon’s orbit around Pluto takes 6.4 Earth days, and one Pluto rotation (a Pluto day) takes 6.4 Earth days. So from Pluto’s point of view Charon neither rises nor sets, but hovers over the same spot on Pluto’s surface, and the same side of Charon always faces Pluto. Get the details:

8. “Death Star” Moon: Mimas

Saturn’s moon Mimas has one feature that draws more attention than any other: the crater Herschel, which formed in an impact that nearly shattered the little world. Herschel gives Mimas a distinctive look that prompts an oft-repeated joke. But, yes, it’s a moon. More:

9. Don’t Be Afraid, It’s Just Phobos

In mythology, Mars is a the god of war, so it’s fitting that its two small moons are called Phobos, “fear,” and Deimos, “terror.” Our Mars Reconnaissance Orbiter caught this look at Phobos, which is roughly 17 miles (27 km) wide. In recent years, NASA scientists have come to think that Phobos will be torn apart by its host planet’s gravity. Details:

Learn more about Phobos:

10. The Moon We Know Best

Although decades have passed since astronauts last set foot on its surface, Earth’s moon is far from abandoned. Several robotic missions have continued the exploration. For example, this stunning view of the moon’s famous Tycho crater was captured by our Lunar Reconnaissance Orbiter, which continues to map the surface in fine detail today. More:

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Solar System: Things to Know This Week

Earth is the ultimate ocean planet (that we know of), but it turns out that our solar system has water in some surprising places, with five ocean-bearing moons and potentially several more worlds with their own oceans. 

1. The Original “Alien Ocean”

Our Galileo spacecraft (1989-2003) detected the first evidence of an ocean beyond Earth under the ice of Jupiter’s icy moon Europa.

2. Lost Oceans

There are signs that Mars and Venus once had oceans, but something catastrophic may have wiped them out. Earth’s natural force field – our magnetosphere – acts like shield against the erosive force of the solar wind.

3. Earth, the Original Ocean World

The search for life beyond Earth relies, in large part, on understanding our home planet. Among the newest Earth ocean explorers us the Cyclone Global Navigation Satellite System, or CYGNSS–a constellation of microsatellites that will make detailed measurements of wind speeds over Earth’s oceans to help understand hurricanes. The spacecraft have moved into their science operations phase.

4. Sister Ships

It’s fitting the first mission to explore an alien ocean is named in honor of fast-sailing clipper ships of old. Our Europa Clipper spacecraft will seek signs of habitability on Jupiter’s moon Europa.

5. Game Changer

Scientists expected Saturn’s moon Enceladus to be a tiny, solid chunk of ice and rock. But, not long after arriving at Saturn, our Cassini spacecraft made a series of incremental discoveries, eventually confirming that a global subsurface ocean is venting into space, with signs of hydrothermal activity.

6. Why Ocean Worlds Matter

“The question of whether or not life exists beyond Earth, the question of whether or not biology works beyond our home planet, is one of humanity’s oldest and yet unanswered questions. And for the first time in the history of humanity, we have the tools and technology and capability to potentially answer this question. And, we know where to go to find it. Jupiter’s ocean world Europa.” - Kevin Hand, NASA Astrobiologist

7. More Alien Oceans

Scientists think Jupiter’s giant moons Ganymede and Callisto also hide oceans beneath their surfaces. Elsewhere in the solar system, scientists hope to look for hidden oceans on far-flung worlds from Ceres in the main asteroid belt to Pluto in the Kuiper Belt.

8. Cold Faithful(s)?

Thanks to our Cassini orbiter we know the tiny moon Enceladus is venting its ocean into space in a towering, beautiful plume. The Hubble Space Telescope also has seen tantalizing hints of plumes on Jupiter’s moon Europa. Plumes are useful because they provide samples of ocean chemistry for oceans that could be miles below the surface and difficult for spacecraft to reach. It’s like they’re giving out free samples!

9. Titanic Seas and Ocean

Saturn’s moon Titan not only has liquid hydrocarbon seas on its surface. It also shows signs of a global, subsurface saltwater ocean–making the giant moon a place to possibly look for life as we know it and life as we don’t know it … yet.

10. Oceans Beyond

Several of the thousands of planets discovered beyond our solar system orbit their stars in zones where liquid surface water is possible–including Proxima-b, a rocky planet orbiting the star nearest to our own.

BONUS: Adopt a bit of YOUR Ocean World

We invite everyone to help us celebrate Earth Day 2017 by virtually adopting a piece of Earth as seen from space. Your personalized adoption certificate will feature data from our Earth-observing satellites for a randomly assigned location, much of it ocean (it is 70 percent of the Earth’s surface after all!). Print it and share it, then explore other locations with our interactive map and get even more Earth science data from NASA’s Worldview website.

Visit to adopt your piece of the planet today!

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Repost from my fanart account…

My D&D Triton, Nimue is the former and disgraced princess of the sea. She’s a paladin/tank and wields a trident. Will post more as the campaign develops c;

I’m a huge fan of mermaids and while I needed Nimue to be able to walk on land- and Tritons tend to have legs as opposed to mermaid tails, the way I solved this problem was to have her fins wrap around her legs to form a traditional mermaid tail, or individually wrap around her legs when she wears her armor or is on dry land. Best of both worlds!

Tritons tend to use the traditional mermaid tail when they need to swim faster and be more stealthy, usually when hunting.

My Tritons are born with their fins tightly wrapped around their developing legs. They will ‘bloom’ and separate when they reach 3-4 years of age.