Astronomical names it's all Greek to me

I have recently finished reading Stephen Fry's (2017), Mythos: a retelling of the Myths of Ancient Greece (Penguin). The reading is easy and fun, with humour typical of Fry's stage presence and other writing.  To read Mythos was also to read a context for the nomenclature of space, a who's-who of astronomical objects and some present day constellations.  I place on my list of recommended reading for astronomy bluffs, though given its placement in a fiction genre it frustratingly lacks both a table of contents and an index.  Mythos is also a treasury for etymologically curious people as clearly Fry loves to understand words.  Read his footnotes, some gems in there also.

To prove the point that space is full of Greek names, I have compiled this summary from a more exhaustive list on the International Astronomical Unions site.  Also worth reading their guide to naming conventions, which describes how decisions are made about how things are named, including planetary features like craters.

The Planets

In English speaking astronomy the eight solar system planets bear the names of Roman gods (Uranus exempted), but is also worth observing that there is correspondence to Greek gods and therefore we could consider that the Greek god is also being referenced.  I have included Pluto and Ceres in the list, because even though they are no longer considered planets, they fit the pattern being described.  Table mostly derived from the Mythology for Dummies Cheat Sheet.  Ceres was discovered in 1801, labelled as planet and 'demoted' to an asteroids in the 1850s.

Roman	Greek	Description
Mercury	Hermes	Messenger of the gods
Venus	Aphrodite	Goddess of love
Gaea	Gaia	Earth
Mars	Ares	God of War
Ceres	Demeter	Goddess of the harvest
Jupiter	Zeus	King of Gods
Saturn	Cronos	Father of Zeus, Son of Uranus
Caelus	Uranus	God of the Sky
Neptune	Posidion	God of the Sea
Pluto	Hades	God of the Underworld

The Moons of the Solar System

The list that follows provides the name of the planet with the name of its moons as indented dot points, only Greek names make it to the list. Roman numerals follow the IAU convention and indicate the planet's orbit order (I assume). Once again I have included Pluto because it fits the pattern.

Earth

• The moon, Selene in Greek, hence the prefix Selenic for 'lunar' features.

Mars

• Phobos (I) - one of the horses that drew Ares chariot (translated 'fear').
• Demios (II) - one of the horses that drew Ares chariot (translated 'flight').

Asteroids

• Eros - god of love
• Ida - a nymph who raised Zeus
• Dactyl (I) - mythological beings who assisted Ida
• Kalliope -
• Linus (I) - 

Jupiter

• Io (I) - one of Zeus' lovers. Changed into a cow to protect her from Hera.
• Europa (II) - one of Zeus' lovers.
• Ganymede (III) - one of Zeus' lovers.
• Callisto (IV) - one of Zeus' lovers. Changed into a bear to protect from Hera.
• Amalthea (V) - naiad who nursed Zeus.
• Himalia (VI) - one of Zeus' lovers.
• Elara (VII) - one of Zeus' lovers.
• Pasiphae (VIII) - one of Zeus' lovers. Wife of Minos.
• Sinope (IX) - Zeus failed to seduce this character.
• Lysithea (X) - child of Zeus.
• Carme (XI) - one of Zeus' lovers.
• Ananke (XII) - one of Zeus' lovers.
• Leda (XIII) - one of Zeus' lovers.
• Thebe (XIV) - one of Zeus' lovers.
• Adrastea (XV) - cared for the infant Zeus.
• Metis (XVI) - one of Zeus' lovers, mother of Athena.
• Callirrhoe (XVII) - step child of Zeus.
• Themisto (XVIII)  - one of Zeus' lovers.
• Megaclite (XIX)  - one of Zeus' lovers.
• Taygete (XX)  - one of Zeus' lovers.
• Chaldene (XXI)  - one of Zeus' lovers.
• Harpalyke (XXII) -  one of Zeus' lovers.
• Kalyke (XXIII)  - one of Zeus' lovers.
• Iocaste (XXIV)  - one of Zeus' lovers.
• Erinomee (XXV)  - one of Zeus' lovers.
• Isonoe (XXVI)  - one of Zeus' lovers.
• Praxidike (XXVII) - one of Zeus' lovers.
• Autonoe (XXVIII)  - one of Zeus' lovers.
• Thyone (XXIX)  - one of Zeus' lovers.
• Hermippe (XXX) - one of Zeus' lovers.
• Aitne (XXXI)  - one of Zeus' lovers.
• Euanthe (XXXIII)  - one of Zeus' lovers.
• Euporie (XXXIV) - daughter of Zeus.
• Orthosie (XXXV) - daughter of Zeus.
• Sponde (XXXVI) - daughter of Zeus.
• Kale (XXXVII) - daughter of Zeus.
• Pasithee (XXXVIII) - daughter of Zeus.
• Hegemone (XXXIX) - daughter of Zeus.
• Mneme (XL) - daughter of Zeus.
• Aoede (XLI) - daughter of Zeus.
• Thelxinoe (XLII) - daughter of Zeus.
• Arche (XLIII) - daughter of Zeus.
• Kallichore (XLIV) - daughter of Zeus.
• Helike (XLV) - daughter of Zeus.
• Carpo (XLVI) - daughter of Zeus.
• Eukelade (XLVII) - daughter of Zeus.
• Cyllene (XLVIII) - daughter of Zeus.
• Kore (XLIX) - daughter of Zeus.
• Herse (L) - daughter of Zeus.
• Dia (LIII) - one of Zeus' lovers.

Saturn

• Mimas (I) - a Titan
• Enceladus (II) - a Titan
• Tethys (III)  - a Titan
• Dione (IV) - Zeus had sex with this person.
• Rhea (V) - a Titaness, mother of Zeus.
• Titan (VI) - a Titan.
• Hyperion (VII) - a Titan.
• Iapetus (VIII) - a Titans
• Pheobe (IX) - a Titaness.

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• Epimetheus (XI) - son of Iapetus.
• Helene (XII) - granddaughter of Kronos. Her beauty triggered the Trojan War.
• Telesto (XIII) - daughter of Oceanus and Tethys.
• Calypso (XIV) - daughter of Oceanus and Tethys.
• Atlas (XV) - a Titan.
• Prometheus (XVI) - son of Iapetus.
• Pandora (XVII) - made from clay at the request of Zeus.
• Pan (XVIII) - god of pastoralism.

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• Methone (XXXII) - daughter of the giant Alkyoneos.
• Pallene (XXXIII) - daughter of the giant Alkyoneos.
• Polydeuces (XXXIV) - son of Zeus and Leda.
• Daphnis (XXXV) - son of Hermes, brother of Pan.

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• Anthe (XLIX) - daughter of the giant Alkyoneos.

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• Aegaeon (LIII) - hundred armed giant.

Uranus

• Nothing here, all moons named after characters in Pope's "Rape of the Lock" or characters from Shakespearean plays.

Neptune

• Triton (I) - sea god, son of Poseidon and Amphitrite.
• Nereid (II) - collective term for the daughters of Nereus and Doris ... Poseidon's attendants.
• Naiad (III) - collective term for water nymphs.
• Thalassa (IV) - sea goddess.  Mother of Aphrodite or Telchines.
• Despina (V) - daughter of Poseidon and Demeter.
• Galatea (VI) - a nereid.
• Larissa (VII) - one of Poseidon's lovers.
• Proteus (VIII) - a sea god, son of Oceanus and Tethys.
• Halimede (IX) - a nereid.
• Psamathe (X) - a nereid.
• Sao (XI) - a nereid.
• Laomedeia (XII) - a nereid.
• Neso (XIII) - a nereid.

Pluto

• Charon (I) - the boatman who ferried souls across the river Styx.
• Nix (II) - goddess of dark and night, mother of Charon.
• Hydra (III) - monster of the underworld.
• Kerberos (IV) - nine-headed guard dog of the underworld.
• Styx (V) - goddess of the underworld.

Dwarf Planets

• Eris - goddess of discord and strife.
• Dsynomia (I) - daughter of Eris, spirit of lawlessness.

Most of the Solar system's moons (there are more than 180 of them) have been discovered in the last 30 years.  The fact that so many of them bear names tied to Greek mythology is not therefore a recognition of ancient knowledge but rather a scientific desire to have systems of naming for such objects.  I for one find such a name more interesting than an alpha-numeric code, which most of these objects would have had prior to gaining their Greek name.

All this amazing cast of characters, and I have not yet started on the stars, or the constellations that include them.  Nor the names of features, like craters, on the astronomical objects listed.  Both areas are rich sources for links to further Greek mythology.

Rescaling the Solar System

The task of this post is to present two resources that introduce students to a basic understanding of the Solar System, along with some ideas about how these resources could be utilised.  It contributes to the Year 5 Australian Curriculum (but is more widely useful) ...

The Earth is part of a system of planets orbiting around a star (the sun) (1) identifying the planets of the solar system and comparing how long they take to orbit the sun (2) modelling the relative size of and distance between Earth, other planets in the solar system and the sun (3) recognising the role of the sun as a provider of energy for the Earth. (ACSSU078)

A previously released resource, Solar System Happy Families (see previous post), may also be of interest.

‘The Hitchhikers Guide to the Galaxy’ says it beautifully

“Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mind bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen...”

But to grasp ‘how big’ requires us to play around with the scale of the objects in a system.  Because of the difference in magnitude of the planet’s size and the distances between them it is not possible to represent both in a diagram.  At best we need to use two scales, one for the planetary size and another for the distances between the planets.  Certainly any representation of the orbits of the planets that would fit in a book would have planets so infinitesimal as to be invisible if distance and size were the same scale.

To grasp both we can conceptualise the Solar System with scaled objects and then place them in the landscape, either in reality (using a walk or a drive) or imaginatively (using maps).  Such representations are a common science outreach tool.  For example, the Solar System Drive in NSW, is scaled so that the 37m dome of the Siding Springs observatory represents the sun.

The Neptune station on the Solar System Drive, NSW. A pull over point on the Newell Highway.

Deeper learning can be achieved if students work on representations based on their own imagining. Solar System Rescaler (link here) provides an online rescaling tool to achieve this.  Based on simple formulas, first written in Excel and now transferred to Google Sheets, the spreadsheet enables a user to enter the dimensions of an everyday object to represent one object in the solar system, for example, what if the Earth were the size of a marble?  The spreadsheet then calculates a scaling factor and rescales both the orbits and the object sizes of a number of nominated objects in the solar system.  Instructions and explanation of the formulas is provided in the supporting documentation linked to via the rescaler.

A couple of examples.

In my backyard I created a representation of the Solar System rescaled so that a 400mm bird bath could represent the sun.  Only the four inner rocky planets would fit inside my yard and I represented these with holes drilled into aluminium plates that I attached to the fence, thus the Earth was 3.6 mm in diameter and 42.8 m away from the bird bath. The furthest planet, Neptune, was 1.29 km away.  Amazingly at this scale, the nearest star, Alpha Proxima at 4 light years away would be represented as being 10,800 km distant from my bird bath.   And what is between us and our nearest star? Well… billions of tiny objects which are so small that on average we could consider the space as ‘empty’.  That is our nearest star! The furthest object visible to the unaided eye is 2.25 million light years away. Space is big!

Aluminium plate for Mars, planet size represented by the hole with orbit of the two moons, Phobos and Deimos, represented by scribed circles.

Lego produced planets for some of their Star Wars models and I like to play around with these in the classroom.  In part because Lego is a familiar object, and for many students is immediately associated with creativity, but also because it is big enough to allow for tactile engagement.

Lego planet element and Lego boulder, with an Australian fifty cent piece for scale.

I start with these two objects a Lego planet, representing earth, and a Lego boulder, representing the moon (the scaling is about right). Invite students to hold the two objects, estimating what they consider to be the correct distance apart to represent the moon’s orbit.  Most will nominate a distance under 600mm.  The true distance is closer to 2.6m.  Below is the output from the rescaler.

Screen grab from the Rescaler.  Note the entry of the planet’s size, 86 mm, in the rescaler column.  Also note that the object type filter is active and displays only planets, the sun and the moon.

It is then possible to ask the question, what if we scaled the Solar System so that the sun was the size of the Lego planet? Segueing from this I produced a postcard resource (link here) which encourages students to decorate a postcard for a Lego representation of the Solar System, asking the question, how big would the Solar System be if any planet were scaled to the size of the Lego element?

Students then research various metrics for the planets, daylength, orbital period, max and min temperature, number of satellites etc, etc.  This information could then be recorded on the card.

Postcard for Jupiter. On the left is a blank lego planet (full size) for students to decorate. On the right the planets name, planetary symbol and a 1:1,000,000,000 dot to represent the planet at that scale.

Suggested extension activities for the postcards include.

a) Having conducted the research into another planet, students could write an imaginative piece pretending they were on that planet and writing a postcard to a friend either on Earth or on another planet in the Solar System.

b) When Lego released the planet element, it was Star Wars themed.  Students could design a Lego build to go inside the planet element, together with an appropriate mini figure that could represent someone who may have been of influence in learning about the planet, or perhaps the god after whom the planet is named.

c) The postcards contain a scaled version of the Solar system (1 is to 1 billion) in the right panel of the card.  Students could lay these out around the school grounds and perhaps share their learning with another class who is not working on the unit.

If you invent other things to do with this please share - use the comments section below.

Solar System Happy Families

I am pleased to announce the release of my card game Solar System Happy Families.

Available

• here as a Google Doc (which will allow for editing of a copy) and,
• here as a PDF (which will eliminate any pagination or font problems).

Scope

Designed with the Australian Curriculum year 5 descriptor clearly in view

The Earth is part of a system of planets orbiting around a star (the sun) - ACSSU078

The game uses play to introduce various elements of the solar system, planets, moons of various planets, phases of our own moon, asteroids and trans-Neptune plutoids. It also allows students to get a feel for some of the types of space missions that have been launched, manned lunar landings, Mars rovers and missions to the outer solar system, and missions to interstellar space, there are 11 families of objects in total.

There are 44 playable cards in a deck, when we consider that the the solar system has over 180 moons and several thousand asteroids, and that we only listed Pioneer 10 and none of it predecessors it is clear that the game is a taster and not a definitive guide.  There is room for an educator to set the creation of 'expansion packs' as an enrichment tool, for example orbiter missions, Chinese missions, trojans, centaurs, craters on the moon, or moons of Uranus - all just suggestions.

Rule systems

The game can work with normal happy family rules, i.e. deal all cards to start and then call for the card you need.  I have preferred to use a hybrid of the rules of happy families and go-fish, that is start with five cards each and have a draw pile left over.  These rules are explained on one of the cards in the deck.  House rules will emerge if the game becomes popular and this is fine.

I have trialled this in a year 5-6 composite class and when asked for feedback I received the following.

"... Solar System Happy Families was a fun and educational game, because I didn’t know some of the moons, ... and planets, like Europa, existed until I played this game.  I liked the fact that it can be a calm, enjoyable and competitive game all at once.”  

The printable file gives 4 colours of cards backs to allow for multiple decks in one classroom, printing instructions and the source information for all the images used in the deck. All images are from Public Domain or Creative Commons sources.