Tag Archives: Saturn

The Slow Month! The Jay Dee Show 39

September is done, and I’m finally doing another video digest. August was VEDA, so I was doing a video every day. But in September, I did fewer videos on my main channel than an entire week in August! Let’s just say that I had a bit of a video-making overload in August, and September was my month to recover. But I was able to make a video for my science channel, too! I did a total of 6 videos on my main channel and 1 on my science channel.

On my main channel, I made mostly Authors Answer videos, but also a couple Star Trek Discovery videos!

First up is Authors Answer #44, all about money! Check it out.

And then came another Authors Answer. But this one is about using real life events to influence writing fiction.

Continuing on with some Japan videos, I visited Meigetsuin, a temple known for its hydrangea. Beautiful place!

And then another Authors Answer, one talking about this blog!

And finally, the two Star Trek Discovery episode reviews. Here’s episode 1:

And episode 2:

Moving on to my science channel, there was a big news story coming from Saturn. Cassini is no more! It’s now burned up in the atmosphere of Saturn. I talked about what happened and looked at some of Cassini’s discoveries.

Coming in the next couple days, I’ll be opening up a new channel! This new channel is all about English. As you may know, I was an English teacher in Japan. I’ve got the itch to teach English again, and I thought, why not make quick lessons on YouTube? So, stay tuned for that!

What did you think of the videos for September? Let me know which ones you liked the most.

The End of Cassini: Crashing Into Saturn

On September 15, the Cassini spacecraft will come to an end. It’s going to crash into Saturn after orbiting it for more than 13 years. That’s a long time.

Cassini has brought us an incredible amount of information. Some of it has been extremely exciting. Lakes on Titan, liquid water ocean on Enceladus, the spongy-looking surface of Hyperion, and the split personality of Iapetus. And then there are the rings and the atmosphere of Saturn. I talk all about that and why Cassini is crashing into Saturn in my most recent science video.

What are some of your best memories of the Cassini mission? Let me know in the comments section below.

A Must See Planetary Alignment

Back in May 2002, I was treated to an amazing planetary alignment. Just after sunset, I could see all of the naked eye planets, Mercury, Venus, Mars, Jupiter, and Saturn all lined up in the sky. You can read about it on the American Association of Amateur Astronomers website, which shows how websites looked back in 2002.

That was the first time I’d ever been able to see Mercury.  But to see all of the naked eye planets was incredible.  It happened again in 2005, but I didn’t see that. However, for the next month, you can see it in the morning just before dawn. So, you have to get up early to see this! It’ll be visible in the east, so you’ll need a good spot to view it from and clear skies. For those of us in the northern hemisphere, it means braving the cold. It begins January 20th and ends on February 20th.

This video does a good job at illustrating what you’ll see.

Are you going to get up early to see this alignment?

Top Ten Largest Moons

This is the newest series to come to I Read Encyclopedias for Fun, the weekly Top Ten. I will be publishing top ten lists of various topics scientific, geographic, and anything related to books, TV shows, and movies. They are not merely lists, however. They also include some interesting information. Some of the lists will be purely factual, while others will be my opinion. So, let’s get started.

Top Ten Largest Moons

10. Oberon

Voyager_2_picture_of_OberonWith a mean radius of 761.4 km, Uranus’ moon Oberon is the tenth largest moon in the Solar System. It has a mass of (3.014±0.075)×1021 kg , and a mean density of 1.63±0.05 g/cm³. It’s the second largest moon of Uranus, and was discovered by William Herschel in 1787. It’s estimated to be about 50% water ice, and differentiated into a rocky core and icy mantle. The surface is slightly reddish and is covered with craters and chasmata. It has only been visited once, by Voyager 2, which mapped 40% of its surface.

9. Rhea

PIA07763_Rhea_full_globe5With a mean radius of 763.8 km, Rhea is the ninth largest satellite in the Solar System. It has a mass of (2.306518±0.000353)×1021 kg, and a mean density of 1.236±0.005 g/cm³. It’s the second largest moon of Saturn, and was discovered by Giovanni Domenico Cassini in 1672. Due to its low density, it’s estimated to be about 75% water ice, and only about 25% rock. It appears it has a homogeneous interior, meaning there is no core. It is heavily cratered and has only a few chasmata or fractures on the trailing hemisphere. It’s been extensively photographed and mapped by the Cassini orbiter currently at Saturn.

8. Titania

Titania_(moon)_color_croppedWith a mean radius of 788.4±0.6 km, Titania is the eighth largest moon in the Solar System, and Uranus’ largest. It has a mass of (3.527±0.09)×1021 kg, and a mean density of 1.711±0.005 g/cm³. It was discovered by William Herschel in 1787. It’s estimated to be around 50% water ice, and may have a rocky core. The surface is cratered fairly heavily, but not as much as other large Uranian moons, meaning it has a younger surface. It features several large chasmata and scarps, pointing towards tectonic activities in its past. It may have a tenuous carbon dioxide atmosphere. About 40% of the surface has been photographed by Voyager 2.

7. Triton

480px-Triton_moon_mosaic_Voyager_2_(large)With a mean radius of 1353.4±0.9 km, Triton is the seventh largest moon in the Solar System, and Neptune’s largest. It has a mass of 2.14×1022 kg, and a mean density of 2.061 g/cm3. it was discovered by William Lassell in 1846. Triton is unique in that it’s the only large moon that orbits its planet in a retrograde direction. Because of this, the tidal forces from Neptune will cause its orbit to degrade and crash into the planet or create a new ring system in about 3.6 billion years. Triton is also very active geologically. It has several nitrogen geysers that have been observed to be erupting. The surface is relatively young, having been resurfaced in the past, leaving it smoother and more reflective. It’s likely to be differentiated, having a core, mantle, and crust. It’s guessed it may have a liquid water ocean beneath the surface. The core likely generates heat to help keep the water liquid. The atmosphere is a thin nitrogen atmosphere, and clouds have been observed. It’s theorised that Triton is a captured moon, likely a Kuiper Belt object.

6. Europa

Europa-moonWith a mean radius of 1560.8±0.5 km, Europa is the sixth largest moon, and the fourth largest of Jupiter’s Galilean satellites. It has a mass of (4.799844±0.000013)×1022 kg and a mean density of 3.013±0.005 g/cm3. It was discovered by Galileo Galilei in 1610. Europa is one of the most exciting satellites in the Solar System for one major reason, it has a large subsurface ocean of liquid water. It’s so large that it has more water than Earth. Because of tidal heating, it is quite possible that it has hydrothermal vents, which are teeming with life in Earth’s oceans. The surface is incredibly smooth and made of water ice. It has features similar to the Arctic polar ice cap and very few craters. The surface is young and constantly being resurfaced. Beneath about 10-30 km of ice, there’s a thick ocean of liquid water, around 100 km thick. And then beneath that is a rocky interior and a metallic core. One of the most prominent features is the lineae, or the extensive lines that cover the surface. These are cracks where fresh water may be coming to the surface, and plates of icy crust move against each other.

5. Moon

LRO_WAC_Nearside_MosaicWith a mean radius of 1737.1 km, the Earth’s Moon is the fifth largest moon in the Solar System. Its mass is 7.342×1022 kg and mean density is 3.344 g/cm3. It’s the second densest moon in the Solar System. It’s the most familiar moon, as we can see it very easily from Earth. Its discovery is prehistoric, since we’ve always known it’s there. The surface is heavily cratered, except in the Maria, which are basins flooded with lava. There are also volcanoes, some of which are relatively young. This suggests a warmer interior than previously thought. The interior is differentiated, with distinct crust, mantle, and core. The surface is dominated by silica, alumina, lime, and iron oxide. It’s tidally locked, so we only see one side of the Moon. The far side is very different, lacking the maria we see on the near side. It’s also the only moon that has been landed on by humans, and one of only two moons that has been landed on by robotic probes.

4. Io

Io_highest_resolution_true_colorWith a mean radius of 1821.6±0.5 km, Io is the fourth largest satellite, and the third largest of Jupiter’s Galilean satellites. It has a mass of (8.931938±0.000018)×1022 kg and a mean density of 3.528±0.006 g/cm3. It is the most dense natural satellite in the solar system, and is also the most geologically active. It has more than 400 active volcanoes, which makes it the most active object in the Solar System, more than Earth. It was discovered by Galileo Galilei in 1610. When Io was first viewed up close, it was a surprise. The surface is a very colourful mixture of red, orange, yellow, white, and black. Several volcanoes can be erupting at the same time, and lava lakes have been observed. The surface composition is mostly silicates, sulfur, and sulfur dioxide. Due to tidal interactions with Jupiter, the interior is constantly being flexed. With an internal structure more similar to terrestrial planets than other moons, it has almost no water ice. It has a crust, mantle, and hot core.

3. Callisto

CallistoWith a mean radius of 2410.3±1.5 km, we’re moving into the top three, and the true heavyweights of the Solar System’s moons. It’s the third largest in the Solar System, and the second largest of Jupiter’s moons. It has a mass of (1.075938±0.000137)×1023 kg and a mean density of 1.8344±0.0034 g/cm3. With a relatively low density, it is about half ice and half rock. It was discovered by Galileo Galilei in 1610. The outermost Galilean satellite, it has far less tidal influence from Jupiter, and therefore has an old, relatively inactive surface. It is covered by craters, and is considered the oldest surface in the Solar System. Unlike other large moons, it’s not very differentiated, and is mostly a mixture of rock and ice covered by a possible liquid water ocean and an icy crust. It has a thin carbon dioxide atmosphere.

2. Titan

Titan_in_true_colorWith a mean radius of 2575.5±2.0 km, Titan is the second largest moon in the Solar System, and Saturn’s largest. It’s even larger than Mercury, but has a smaller mass. It has a mass of (1.3452±0.0002)×1023 kg and a mean density of 1.8798±0.0044 g/cm3. It was discovered by Christiaan Huygens in 1655. It is the only satellite outside the Earth-Moon system that has been landed on by a space probe, the Huygens lander. It has a very thick atmosphere, thicker than Earth’s and with a 45% higher air pressure at the surface than Earth’s. The composition is mostly nitrogen with some methane and hydrogen. What makes Titan incredibly interesting is the surface. It is very Earth-like, with mountains, rivers, and lakes. However, the lakes are not water, but liquid hydrocarbons, mainly ethane and methane. There are some craters, but the surface appears to be quite young, with possible cryovolcanism. Basically, the surface is like Earth’s but ice replaces rock and hydrocarbons replace water. It’s a differentiated body with a silicate core, an ice layer, then a possible liquid water ocean, and the ice crust.

1. Ganymede

Ganymede_g1_true-edit1With a mean radius of 2634.1±0.3 km, Ganymede is the largest moon in the Solar System, and Jupiter’s largest. It has a mass of 1.4819×1023 kg and a mean density of 1.936 g/cm3. It was discovered by Galileo Galilei in 1610. The surface is quite complex with older cratered regions and a younger grooved terrain. It’s mainly water ice with some carbon dioxide and sulfur dioxide. Some salts hint at a salty ocean beneath the surface. It’s fully differentiated with a hot iron-nickel core and silicate mantle. It’s believed there’s a thick liquid water ocean between two layers of ice. There’s an extremely tenuous oxygen atmosphere. Ganymede has its own magnetic field, and has even been observed to have aurorae. This also helps strengthen the theory that there’s a salty ocean. Tidal stresses from Jupiter aid in heating the interior, which makes Ganymede another possible candidate for life.

If you have any questions about these or any other moons of the Solar System, I’ll do my best to answer them. As this was one of my biggest interests in university, I’ve been paying attention to news related to the Solar System and its moons. Ask your questions or leave comments in the comments section below.

Astronomy Quick Facts – Anthe

Anthe is a very small moon of Saturn, and a member of the Alkyonides. It’s also known as Saturn XLIX. It was discovered by the Cassini Imaging Team on May 30, 2007. Very little is known about it.


  • Mean radius: 1 km (estimated)
  • Mass: 5×1012 kg
  • Density: Unknown
  • Surface gravity: Unknown
  • Albedo: Unknown
  • Temperature: Unknown
  • Mean orbital radius: 197,700 km (semi-major axis)
  • Orbital period: 1.03650 d
  • Inclination: 0.1° to Saturn’s equator
  • Eccentricity: 0.001

Name Origin

Anthe is one of the Alkyonides. She was one of the seven daughters of Alcyoneus, who was killed by Heracles. When he died, they threw themselves into the sea and were changed into halcyons by Amphitrite.

5 Interesting Facts

1. It orbits between Mimas and Enceladus.

2. Its 10:11 mean-longitude resonance with Mimas causes its semi-major axis to vary by 20 km every 2 years.

3. The other Alkyonides, Methone and Pallene are in similar orbits, and they may have a similar origin, possibly a larger moon broken apart by a large impact.

4. The Anthe Ring Arc may be caused by micrometeoroid impacts on Anthe. This partial ring appears in the vicinity of Anthe.

5. It was the sixtieth confirmed moon of Saturn.

Not much is known about this moon, but there are several images available. Here’s another one with the ring arc.


Encyclopedia Entry #9 – Albiorix

Albiorix is a small moon of Saturn’s that was discovered in 2000.  It’s also known as S/2000 S 11.


  • Dimensions: 32 km in diameter
  • Mass: unknown
  • Density: unknown
  • Surface gravity: unknown
  • Albedo: 0.04
  • Temperature: unknown
  • Mean orbital radius: 16,182,000 km
  • Orbital period: 783 d
  • Inclination: 34.207° (to the ecliptic)
  • Eccentricity: 0.477

Name Origin

Albiorix was a Gallic giant that’s said to have been king of the world.  It originated in Gaul (now France) and is associated with the Roman god Mars.

5 Interesting Facts

1. The colour has been determined to be light red.

2. It has a 13.19 hour rotation period.

3. It’s the largest member of a group of satellites called the Gallic satellites.  These satellites may have originally been a larger moon.

4. Colour variations suggest a large crater on the surface.  There’s a hypothesis that Erriapus and Tarvos may be fragments of Albiorix from this collision.

5. It was discovered by the team led by M. J. Holman, which has discovered a total of 11 satellites.

There isn’t much known about Albiorix, as it is orbiting quite far from Saturn.  There is no image available.

Encyclopedia Entry #7 – Aegir

Aegir is a small moon of Saturn’s that was discovered in 2004 and observed until 2005.  It’s also known as Saturn XXXVI.


  • Dimensions: 6 km in diameter
  • Mass: unknown
  • Density: unknown
  • Surface gravity: unknown
  • Albedo: unknown
  • Temperature: unknown
  • Mean orbital radius: 20,751,000 km
  • Orbital period: 1,117.52 d (retrograde)
  • Inclination: 140°
  • Eccentricity: 0.237

Name Origin

Aegir is a sea giant from Norse mythology.  He is known for hosting parties for the gods and serving ale brewed in a large cauldron.  He is the son of Fornjótr and the brother of Logi and Kári.

5 Interesting Facts

1. Aegir was discovered at the same time as 11 other moons of Saturn by the use of telescopes on Mauna Kea.

2. It’s in a retrograde orbit, meaning it orbits backwards when compared to most satellites.

3. It takes more than 3 years to orbit Saturn.

4. Scott S. Sheppard, one of the discoverers of Aegir, has discovered/co-discovered 75 moons as of this date (May 4, 2014).

5. It’s really hard to write 5 interesting facts about a moon that has very little known about it.  There isn’t even a photo available that I could find.

Encyclopedia Entry #6 – Aegaeon

Aegaeon is a tiny moon of Saturn, and is also known as Saturn LIII or S/2008 S 1.  It was discovered by the Cassini team on August 15, 2008.

This series of images shows the movement of Aegaeon to the right of the ring.


  • Dimensions: about 500 m
  • Mass: unknown
  • Density: unknown
  • Surface gravity: unknown
  • Albedo: unknown
  • Temperature: unknown
  • Mean orbital radius: 167,500 km
  • Orbital period: 0.80812 d
  • Inclination: 0.001°
  • Eccentricity: 0.0002

Name Origin

Aegaeon was named after Aegaeon, one of the Hekatonkheires, which were the children of Gaia and Uranus.  They were seen as hideous monsters by Uranus and thrown into Tartarus.  Later, Zeus rescued them and thought they would be good allies in the fight against the Titans.  They were giants with 100 hands and 50 heads, and could throw 100 mountain-sized rocks at one time.

5 Interesting Facts

1. It orbits within the G ring of Saturn and is probably a major contributor to it.

2. It orbits in a 7:6 resonance with Mimas.

3. It’s the second smallest known moon of Saturn and second smallest in the solar system.

4. Although it’s suggested it’s 500 m in diameter, it hasn’t been measured.  The size is based on the assumption that its albedo is similar to Pallene’s.

5. In mythology, Aegaeon was also known as Briareus.

Due to the lack of information about this moonlet, the interesting facts were not very interesting.