About Stamp Collecting Month and stamps
In October every year, Australia Post celebrates Stamp Collecting month (SCM). It has been going strong since 1993 and this year's fantastic theme is "Our Solar System".
The "Our Solar System" education material (unit of work, facts, and cross-curricular lesson ideas) developed for this year's Stamp Collecting Month is a resource suitable for use at any time of the year.
Eight stunning stamps have been developed this year and below are some facts about the planets they feature. In the Students section of the website you will find expanded versions of these facts.
About the "Our Solar System" SCM stamps
Mercury - a 35c stamp
Closest to the Sun, Mercury is the smallest planet in our Solar System (about 4,900 km in diameter), its surface baked and wrinkled by the Sun's intense heat. Mercury has the largest temperature variation between day and night of any of the planets, with night time surface temperatures down to -173°C and daytime highs of 427°C. Mercury has no atmosphere and its arid surface is scarred by countless impacts from asteroids, meteors and comets.
Venus - a 70c stamp
Hidden under a blanket of clouds, Venus is a hellish world of crushing atmospheric pressure, high temperature and acid rain. Similar in size to the Earth, with a diameter of 12,100 km, Venus is the hottest world in our Solar System, its thick carbon dioxide atmosphere trapping heat like a greenhouse, so that the surface temperature reaches 462°C − hot enough to melt lead. Seen from Earth, Venus is the brightest object in the night sky apart from the Moon.
Earth - a 70c stamp
Earth is the largest of the "terrestrial", or rocky, planets (12,742 km in diameter). With its vast oceans and protective atmosphere, our home planet has proved just right for the development of life and is the only world in the universe where life is currently known to exist. The atmosphere is composed mainly of nitrogen (78 percent) and oxygen (21 percent), shielding us from harmful infrared, ultraviolet, X-rays and gamma-rays. Earth is the only place in our Solar System where water exists in all three forms − solid, liquid and gas.
Mars - a 35c stamp
Mars is about half the diameter of the Earth, with a surface temperature range of -125°C to -20°C. Mars has lost its surface water (frozen water may exist as permafrost beneath the surface) and possesses only a very thin carbon dioxide atmosphere and a surface pressure less than one percent that of Earth. Most of Mars' atmosphere was either oxidised into its iron rich surface (forming the rusty red colour we see today) or lost to space over time due to Mars' weak gravity. Microbial life may have evolved on Mars billions of years ago but whether any still exists today is a matter for further exploration.
Jupiter - a 70c stamp
The largest planet in the Solar System, Jupiter is a "gas giant" − a huge ball of hydrogen and helium gas with possibly a small rocky or icy core. With an equatorial diameter of 141,000 km, Jupiter is so massive that 1,000 Earths could fit inside it. One of Jupiter's most recognisable features is the Great Red Spot, a huge anticyclonic storm larger than the Earth, that has been raging for more than 400 years. Jupiter has a ring system, consisting of four rings, and 67 moons have so far been discovered.
Saturn - a 70c stamp
Famous for its glorious and complex ring system, Saturn is the sixth planet from the Sun and has an equatorial diameter of 120,536 km. It is made primarily of hydrogen, but its upper cloud layers include ammonia and water ices. Saturn's magnificent ring system is made up of billions of pieces of water ice ranging in size from a centimetre to chunks the size of icebergs. Saturn has 62 known moons, some of which play an important part in shaping the structure of the ring system.
Uranus - a 70c stamp
Uranus is an unusual world, tipped on its side by an ancient impact. With an equatorial diameter of 50,000 km, Uranus takes 84 Earth years to complete its orbit of the Sun. Uranus has a smoggy atmosphere of hydrogen, helium and methane over an icy interior. It has the coldest planetary atmosphere in the Solar System, with a minimum temperature of −224.2°C. A methane haze covers the upper layers of the atmosphere and hides the clouds and storm activity below. Uranus has 13 known rings, and 27 known moons.
Neptune & Pluto - a 70c stamp
Neptune is the outermost of the major planets. Neptune's atmosphere is wracked by fierce winds (measured at travelling 600m per second) and giant storms. Neptune takes 164.8 years to complete an orbit about the Sun, but its day lasts just over 16 hours. Neptune has a thin system of five rings, composed of ice particles and dust grains, and 14 known moons.
Pluto was once considered a planet, but is now categorised as a dwarf planet. It is included on the Neptune stamp as a representative of the smaller bodies in our Solar System.