Royal Australian Mint’s domed astronomy series comes to a close by peering into the sun

The last in the Royal Australian Mints latest domed astronomy coin series is now with us. Titled The Earth & Beyond it’s a three coin series showing of the Earth, the Moon, and now, the Sun. Collectors of the hit Southern Sky series and its follow ons will no doubt love this one as like those earlier issues, the RAM has done a top job with the production and strike of these.

These are one-ounce fine silver coins that are true domed strikes. The latest coin has a concave reverse face depicting the Sun in colour, surrounded by a clean border holding a relatively intricate themed pattern. The pattern is basically the same in concept to the previous pair of coins, but differs in the detailing. The concave obverse has a clean proof finish with the obligatory effigy of Queen Elizabeth II at its centre. The RAM is still using the Ian Rank Broadley effigy, but it’s likely the later Jody Clark one will start to be employed on their coins over the next couple of years. The interesting design of interlocking orbital pathways, each with one of the eight planets upon it, remains around her visage.

Presentation consists of a good quality coin box – nothing fancy, but neat and decent – and a certificate of authenticity is enclosed. The mintage of 5,000 is usually gone in short order, and indeed the Royal Australian Mint have already exhausted their own allocation. Fortunately, distribution outside of Australia is being handled by EMK, and they still have them for sale, as well as several of our sponsors. Expect to pay around €100 for one of these very cool coins. They’re popular for good reason and we hope the mint continues the theme with something new, especially in this anniversary year of the moon landings.


The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System. Roughly three quarters of the Sun’s mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.

The Sun is a G-type main-sequence star (G2V) based on its spectral class. As such, it is informally and not completely accurately referred to as a yellow dwarf (its light is closer to white than yellow). It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process.

The Sun is roughly middle-aged; it has not changed dramatically for more than four billion years, and will remain fairly stable for more than another five billion years. It currently fuses about 600 million tons of hydrogen into helium every second, converting 4 million tons of matter into energy every second as a result. This energy, which can take between 10,000 and 170,000 years to escape from its core, is the source of the Sun’s light and heat.

In about 5 billion years, when hydrogen fusion in its core has diminished to the point at which the Sun is no longer in hydrostatic equilibrium, its core will undergo a marked increase in density and temperature while its outer layers expand to eventually become a red giant. It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable. After this, it will shed its outer layers and become a dense type of cooling star known as a white dwarf, and no longer produce energy by fusion, but still glow and give off heat from its previous fusion.

COMPOSITION 0.999 silver
WEIGHT 31.1 grams
MODIFICATIONS Domed, coloured
BOX / COA Yes / Yes