Tuesday, 26 July 2016

Jupiter’s moon Ganymede

Jupiter’s moon Ganymede

Helena Puumala's SF Romance series features the planet Kordea, home to a race of beautiful and powerful psychic aliens, known as the Witches of Kordea.  The planet has seven moons, an extraordinary arrangement for a terrestrial sized planet in its star's habitable zone. 

But, more on that at the end of the blog.  Basically, the book gives me the opportunity to do a mini-tour of some of the major moons of our solar system.

Here are a few facts about Ganymede, courtesy of Wiki:

  • It's the largest moon in the solar system and the largest in Jupiter's system.
  • It is one of the four original moons discovered by Galileo (thus, referred to a Galilean moon).
  • It is the third farthest from Jupiter of the four Galilean moons.  It is easy to find in a small telescope.
  • It has its own magnetosphere (magnetic field), the only moon known to have one.  This causes auroras around the poles (northern/southern lights).
  • It participates in a 1:2:4 orbital resonance with the two Galilean moons closest to Jupiter, Io and Europa.  That means, for every one time Ganymede goes around Jupiter, Europa goes around twice and Io goes around four times.
  • The orbital resonances among these moons is the main reason why they have internal oceans.  The flexing of the moons, due to the tidal interactions caused by the resonance, create heat, which keeps the oceans liquid.  These are many kilometers underneath an icy crust, which acts as an insulating blanket.  It is speculated that they might be a habitat for life.
  • Having said that, in the case of Ganymede, radiogenic (decay of radioactive elements) heating is important as well.
  • Ganymede is actually larger than Mercury, but only has about half of that planet’s mass (Mercury is much denser and has a large iron core).
  • That being said, Ganymede also has a liquid iron-rich core.
  • It is also composed or silicate rock and ice (thus it is less dense than Mercury).
  • It has an internal ocean, which probably contains more water than the Earth’s oceans.
  • About one third of it is heavily cratered and dark, with the rest being a lighter colour.  The lighter regions are evidence of tectonic activity, related to tidal heating.
  • The presence of a deep subsurface saltwater ocean is inferred from its interactions with Jupiter's magnetic field, best explained by a highly conductive fluid at depth.
  • It is tidally locked with Jupiter, like our moon is with Earth.  That means the same side always faces the planet (though there is some libation, or rocking).
  • Its albedo is about 43% (about 43% of the light falling on it is reflected). 
Here's a recent picture of Ganymede, taken by NASA's new Juno probe, on July 5, 2016.

Ok, that’s pretty small (though it’s a nice shot of Jupiter and three of its big moons and it is one of the first photos from the newest solar system explorer), so here’s a photo taken by NASA’s Galileo probe in 1987.

The moon Ganymede and Love and Intrigue Under the Seven Moves of Kordea

Helena Puumala's SF Romance series features the planet Kordea, home to a race of beautiful and powerful psychic aliens, known as the Witches of Kordea.  The planet has seven moons, an extraordinary arrangement for a terrestrial sized planet in its star's habitable zone.

In fact, the moons of Kordea are a central element in Book 2.  The cover below actually borrows the moon Callisto, one of the moons of Jupiter

The Witches’ Stones Series

The Witches' Stones, Book 1 - Rescue from the Planet of the Amartos

Young Earth woman and spaceship mechanic, Sarah Mackenzie, has unwittingly triggered a vast source of energy, the Witches' Stones,  via her psychic abilities, of which she was unaware.  She becomes the focal point of a desperate contest between the authoritarian galactic power, known as The Organization, and the democratic Earth-based galactic power, known as The Terran Confederation.  The Organization wants to capture her, and utilize her powers to create a super-weapon; the Terra Confederation wants to prevent that at all costs.  The mysterious psychic aliens, the Witches of Kordea also become involved, as they see her as a possible threat, or a possible ally, for the safety of their own world.

A small but fast scout-ship, with its pilot and an agent of the Terra Confederation, Coryn Leigh, are sent to rescue her from a distant planet at the very edge of the galaxy, near space claimed by The Organization.  Battles, physical and mental, whirl around the young woman, as the agent and pilot strive at all costs to keep her from the clutches of the Organization.


The Witches' Stones, Book 2 - Love and Intrigue, Under the Seven Moons of Kordea

Sarah has taken refuge on the planet of Kordea, where she is also learning how to control her psychic abilities, through the tutelage of the Witches of Kordea.  Coryn Leigh has now taken up the position of Confederation diplomat to the Kordeans, but he is also charged with keeping the Mackenzie girl safe at all costs.  During their time on the planet, an attraction between them grows, though they try to deny it, to themselves and each other.
But The Organization has plans of its own, including threatening the destruction of the planet Kordea, via destabalizing the orbit of Lina, one of its many moons.  The Organization proves that its threats are in deadly earnest, so, ultimately Sarah, Coryn and the Witches of Kordea must take the fight to the enemy.  Thus is borne a dangerous mission, to  a planet where their foe has based the weapon that threatens Kordea, and ultimately, the balance of power throughout the galaxy.  Sarah and Coryn agree that the machine must be destroyed, even at the possible cost of their own lives and growing love.

The Witches' Stones, Book 3 - Revenge of the Catspaw

Sarah and Coryn have become married, under the traditions of the Witches of Kordea.  But the marriage is performed by the Eldest of the most important coven, a rare honour, that comes with a blessing and a curse.  The slow working out of this blessing and curse forms the backdrop to the story.

Having come so close to their goal of enhancing their weaponry via Witches' Stone power, The Organization will not give up.  In order to lure Sarah into their trap, and thus have her become their Catspaw (someone who is forced into helping another, against their will) they need bait, and Coryn becomes the bait.  He also comes under the domination of a particularly nasty Elite of The Organization, one "Evil Evilla" Copoz.

Sarah, and a picked group of companions, must re-enter The Organization space, this time to the very heart of the empire, to rescue her husband, as he has done for her in the past.  They do so at great peril, but nothing can stop the terrible Revenge of the Catspaw.


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