Category Archives: Solar System Exploration

Solar System Exploration – The Kuiper Belt

Beyond the orbit of the outer giants, beyond the orbit of Pluto even is a region of the solar system is the Kuiper belt. A place where the material left over from the creation of the solar system resides. We’re not quite into interstellar space (the space between the stars) yet, in fact we’re not totally sure where that begins yet. The Voyager probes that are the farthest human object from Earth are helping us to find this out.

The Kuiper belt isn’t a single object, it’s many object forming a ring around the sun from the orbit of Neptune’s e (30AU’s) to 50 AU’s from the sun. It’s in this belt that frozen comets, and icy dwarf planets are made. Pluto and Neptune’s moon Triton are thought to be Kuiper belt objects, captured and brought nearer to the sun. But what else do we know is out there?

Dwarf Planets

The Kuiper belt is known to be the region of a number of Dwarf planets:

kbos (1)







Are the main bodies, but other smaller object such as Ixion, Varuna and Orcus are continually being discovered. Pluto is also now classified as a dwarf planet and a Kuiper belt object and Neptune’s moon Triton is suspected to be a large Kuiper belt object that was captured by Neptune’s gravity as it orbits Neptune the wrong way. Triton is made up in a very similar way to Pluto to give further weight to this theory.


Voyager 2’s flyby in 1989 made discoveries of volcanoes or frozen methane and details on terrains which up until then we didn’t know existed. It was our first glimpse of what a Kuiper belt object was.




New Horizon’s flew past Pluto on 15th January 2015. The historic encounter brought back images and data of a world which up until then was almost completely unknown. p until then Pluto and it’s largest moon Charon had merely been a small and detail-less point of light in even the most powerful telescope.


There was always the possibility that New Horizons would be used to explore other Kuiper belt objects. Now it has been granted it’s second mission and New Horizons has been steered to make a close encounter with the rather unromantically named 2014 MU69 on January 1st 2019.

New Horizons Kuiper Belt Object Encounter

This will be the furthest object ever encountered by a human spacecraft to date at over 43 times the distance the Earth is from the Sun. What we will find is a mystery, it might be another ball of frozen gas, rock and ice or something completely different. Either way it will give us more information about what is in the Kuiper belt.


Further Exploration:

The Kuiper belt is a long, long way off and it takes a long time to get there. Any future missions are going to have to overcome this problem and justifying going out there is another problem. This is why New Horizons is the first and only probe to go out there and look at anything. Maybe we can look at more before New Horizons speeds out of the solar system. But in the meantime, advances with space telescopes mean we’re getting much more data that we ever have been before.

Hubble was used to plan the New Horizons flyby of Pluto, looking for other moons that needed to be avoided. Hubble found a small handful, handy to know when you’re shooting long distance like that. Dwarf planets in the Kuiper belt are giving up more of their secrets and revealing moons – There’s a whole solar system out there!


Solar System Exploration – Pluto


Pluto was discovered in 1930 by Clyde Tombaugh. Analysis of the outer planets suggested a planet out beyond Neptune and having taken photographs of the night sky and comparing them the movement of Pluto across the sky gave it’s position away. The mass of Pluto did not account for the gravitational anomalies, but Pluto was originally designated a planet and named.

Pluto is the Greek God of the Underworld, whose earlier name was Hades. Pluto was seen as a more positive figure, being a God of the afterlife rather than death.



Facts about Pluto

Some of the key facts about Uranus and how it compares with Earth:

  • Diameter 2,300km (0.18 x Earth’s)
  • 1 Pluto Day = 6.4 days long.
  • 1 Pluto year = 247.9 years.
  • Atmosphere = 96% Hydrogen, 3.2% Helium.
  • Volume = 0.006 times that of Earth.
  • Distance from the Sun = 29 – 49 x further than Earth.
  • Pluto has 5 known moons.
  • Mass is over 0.002 x  Earths mass.



Moons of Pluto

The biggest moon of Pluto is Charon (pronounced Sharon), there are four others moons of Pluto – Styx, Nix Kerberos and Hydra. All of them keeping with the theme of the underworld, Charon being the carrier of souls to the underworld across the river Styx.


Charon was discovered in June 1978 by James Christy, becasue of the small namture of these obects and the great distance Charon merely appreaded as bulge to Pluto. The debate about whether Charon was a moon or a feature of Pluto was finally settled when Pluto’s orbit aligned with Earthsbetween 1985 and 1990. Charon was named after James’s wife, whose nickname was Char. When this conincided with Greek Mythology the name was adopted.

Charon seems to be made up manly by water ice, however there is differentiation between the nothern and southern sides of the moon. This can be seen with the relatively craterless north side and the cratered southern side. The dive to this can be seen with the enourmous crack between the two halves.




After Pluto was discovered, a number of other objects similar in size to Pluto or larger were discovered in an area called the Kuiper belt, where Pluto resides. This caused debate about whether Pluto was a planet or not.

In 2006 the IAU (International Astronomical Union) decided that a planet must fulfill three criteria to be designated aplanet. These are:

  1. It must orbit the sun.
  2. It must have enough mass to form a nearly round shape (a perfectly round shape won’t be achieved).
  3. It must have cleared the neighbourhood. This means it’s must be the most grvitationally dominant object in it’s system.

Becasue Pluto doesn’t meet the third criteria it was descided to re-classify Pluto to a dwarf planet. This decision has met with controversy and the debate hasn’t ended.



Holst never wrote a piece specifially for Pluto, however his Ode to death based around WWI events feature death heavily and Rachmaninov’s The Isale of the Dead could also derive inspiration from his world.







Recent Events

In July 2015 the New Horizon’s space probe flew past Pluto, taking pictures and making a variety of observations. This was the first time that a probe had visited the world. This was a flyby mission because the speed that New Horizons was travelling was so fast that Pluto would not be able to capture it and it couldn’t carry enough fuel to slow it down enough.

New Horizons was lauched at huge speed in order to reach Pluto in ten years, it had gone beyond the Moon’s orbit in a day and had reached Jupiter in about a year. Using it’s gravity to give it further speed and slingshot it on course to it’s destination. This also give us an idea of the huge expanse New Horizon’s had to cover and how distant Pluto is.



Despite this being only a flypast mission New Horizon’s gave us an amazing glimpse at a world we knew nothing about. Just like Triton around Neptune there was far more than we could expect. With a huge heart shaped plain of frozen Nitrogen, to huge ridges and mountains there was so much to explore an analyse, more than perhaps they ever expected.

Pluto -snow mountains 1


The future for New Horizons isn’t certain, after Pluto it could be sent to investigate other Kuiper Belt objects or it could be left to speed out of our solar system and towards the stars. But our first look att his world has been amazing, who knows if we will ever visit again in our lifetimes?

Simon 🙂

Solar System Exploration – Neptune


Neptune was discovered in 1846, the credit of discovery is split between Urbain Le Verrier and John Couch Adams. Both these astronomers used permutations in the orbit of Uranus to locate Neptune before observing it.  Neptune is the only planet to have been discovered from mathematical computation rather than direct observation. Although Galileo had observed Neptune in 1613 and had mistaken it for a star, so he is not credited for it’s discovery. Neptune is named after the Roman God of the sea and is also known as Poseidon as the Greek god of the sea.

Neptune is composed of an icy / metallic core and a helium / hydrogen atmosphere, the core making up  90% – 95% of it’s mass. The remaining 5% = 10% is it’s helium / hydrogen atmosphere. By comparison the core’s  is  between 10 x and 15 x Earth’s mass.


Facts about Neptune

Some of the key facts about Uranus and how it compares with Earth:

  • Diameter 49,200km (3.8 x Earth’s)
  • 1 Neptune Day = 16h 06m hours long.
  • 1 Neptune year = 165 years.
  • Atmosphere = 18% Hydrogen, 19% Helium.
  • Volume = 57 times that of Earth.
  • Distance from the Sun = 30 x further than Earth.
  • Neptune has 14 known moons.
  • Mass is over 17 x  Earths mass, but spread over a larger object.



Moons and rings

Many of Neptune’s moons have not been discovered until recent times, some not until the 1980’s from Earth and then in 1989 with the Voyager 2 flyby and still subsequently with Hubble.

Neptune has some amazing names attached to it’s Moons like Triton, Larissa, Thalassa, Despina and Galatea. Here a few that we know something about.



Triton is named for the son of Poseidon in Greek mythology, it was discovered in 1846 by William Lassell.

Triton has a retrograde orbit, this means it orbit Neptune the opposite way to the other moons, because of this and it’s similar composition to Pluto it’s been suggested that Triton is a captured dwarf planet.

Made up of a surface of frozen nitrogen and 30-40% water ice. Triton is a very cold place to be with temperatures of -38K (-235C). Despite these frozen conditions Triton is one of the few moons in the solar system that’s know to be volcanic.

The volcanism doesn’t involve hot lava as on Earth, rather this is cryo volcanism. The sub surface Nitrogen vapourises under the surface until the pressure build enough to erupt to the surface. When Voyager 2 passed by in 1989 it captured images of geyser like eruptions coming from the surface.













Names after the shape changing God of the sea Proteus is 420km across and is the second largest of Neptune’s moons. It was discovered by Voyager 2 while on approach to Neptune. It wasn’t discovered from Earth because it is so close to Neptune.




Larissa was discovered from Earth by a star occultation in 1981. It’s the fourth largest of Neptune’s moons and is made up of debris from other moons smashed up by Triton.



During the Voyager 2 flyby’s it discovered and photographed the rings of Neptune, faint and thin but several sets of rings were discovered. This settled a long standing discussion about discoveries of ring from Earth that couldn’t be substantiated. As usual these rings are likely to be made up of rock and ice.




This is the final piece in Holst’s The Planets suite. With Neptune being 30x further from the sun than the Earth it’s a mysterious place and this is beautifully captured in his piece in Neptune.



Recent Events

The first and only spacecraft to have visited Neptune is Voyager 2 back in 1989. It carried out a flyby mission, taking photographs taking measurements of Neptune and it’s moons, finding out anything it could about this mysterious world.


What was immediately obvious is that Neptune is a world that’s very different from it’s neighbour Uranus. Neptune is a world that is visibly active with storms that have wind speeds over the speed of sound, clouds and spots.

Voyager 2 picked up the great dark spot on it’s approach, with smaller storms in in the lower bands of the planet. As Neptune is so far from the Sun, the most likely cause of these storms is the internal heating effect of the planet itself. Voyager found so much when it visited this distant and mysterious world, things that from Earth would be so difficult to observe. Storms, rings, volcanoes on Triton. There was far more than anyone expected or could have hoped for.

Artist’s impression of how Triton, Neptune’s largest moon, might look from high above its surface. The distant Sun appears at the upper-left and the blue crescent of Neptune right of centre. Using the CRIRES instrument on ESO’s Very Large Telescope, a team of astronomers has been able to see that the summer is in full swing in Triton’s southern hemisphere.

There are no plans to go back and visit Neptune in the near future. The legacy that Voyager left behind as it left our solar system lives on though. With so much to go back for it’s only a matter of time before blue gem has to give up it’s secrets for us.

Simon 🙂

No ownership claimed on images – Credit NASA / ESA.


Solar System Exploration – Uranus


We’re really getting far away from the sun now as our exploration takes us to Uranus. Uranus is the first planet to have been discovered in relatively modern times with a telescope. It was discovered by William Hershel in 1781 who at first thought he had discovered a comet.

Uranus is the ancient deity God of the sky Ouranos, in Greek mythology. Father of Cronos (Saturn) and grandfather of Zeus (Jupiter).

Uranus is composed of an icy / metallic core and a helium / hydrogen atmosphere. The exact composition is not exactly known, but between 9 x and 13 x Earth’s mass makes up it’s core, the little remaining mass is it’s atmosphere.


Facts about Uranus

Some of the key facts about Uranus and how it compares with Earth:

  • Diameter 50.700km (4 x Earth’s)
  • 1 Uranus Day = 17h 14m hours long.
  • 1 Uranus year = 84 years.
  • Atmosphere = 96% Hydrogen, 3.2% Helium.
  • Volume = 63 times that of Earth.
  • Distance from the Sun = 20.11 x further than Earth.
  • Uranus has 27 known moons.
  • Mass is over 14 x  Earths mass, but spread over a larger object.
  • Uranus’s magnetic field extends at right angles to the other planets.




Uranus has 27 known moons, the 5 main moons are:


uranus- miranda.jpg

Named after Shakespeare’s character in the tempest, it was discovered in 1948 by Gerard Kuiper. At 470km it’s the smallest known object to be spherical under it’s own gravity. It’s tidally locked to Uranus so only one side ever faces it.

It’s surface is one of the most diverse in the solar system, this was discovered in the 1986 Voyager 2 flyby. It’s been suggested that  this is due to internal heating from Miranda’s interaction with the other nearby moons.


uranus ariel








Discovered in 1851 by William Lassell, Ariel is named after two characters in literature. Composed mainly of rock and ice Ariel is 1,150km  across. Several different terrain types have been identified on Ariel, Ridged, cratered and plains, each of these giving clues to the age of the different terrains and how the moon was formed.


uranus umbriel

Umbriel was also discovered in 1851 by William Lassell, named after a character in the poem The Rape of the Lock by Alexander pope. Umbriel is the darkest Uranus’s moons, again it’s made of rock and ice, it’s the most heavily impacted of the moons and this has a lot to do with how the surface was made. At 1,160km wide it’s Uranus’s third largest moon and the third furthest from Uranus.


uranus titania.jpg

Titania was discovered in 1787 by William Herschel, is named after the queen of the fairies in A Midsummer Nights Dream. Titania is the largest of Uranus’s moons at 1,578km and the 8th largest in the solar system. Titania’s surface seems relatively less damaged by craters, this could be due to a surface melting that occurred, obliterating the old surface.


uranus oberon

Titania was discovered in 1787 by William Herschel, is named after the king of the fairies in A Midsummer Nights Dream. Oberon is 1,522km in diameter, the second largest of Uranus’s moons, it’s heavily cratered with an apparent slight red tint. Like all the other moons, it’s made mainly of rock and ice and is the furthers from Uranus.




Uranus has rings, like all the outer planets. They were discovered from Earth in an unusual way though. An airborne telescope flying over the pacific was using Uranus occultation of a star to make observations of it’s atmosphere. When the signal started dipping they thought that instrument faults had ruined their data.


It was only after comparing the data before and after the occultation that they realised the ring dips were symmetrical – that had found the rings of Uranus.





The piece that Holst composed for Uranus is unusual to me, I’m not sure what the images were in his mind when it was written. But nonetheless, like a magician it didn’t give up it’s secrets easily and still doesn’t.


Recent Events


Voyager 2 is to date the only human space craft to have visited Uranus. It flew past the planet in 1986, using the planet’s gravity to  guide it towards it’s final destination of Neptune.

On it’s approach to Uranus the scientist were expecting to be able to see more detail in the atmosphere as the probe approached. Even at a close distance Uranus’s atmosphere is virtually featureless. Only a few storms at very close range yielded any detail.


This was the view of the planet on it’s approach, the rings were not visible as they are faint.


Voyager passed by Uranus and used it’s gravity to fling it towards Neptune, it’s final destination in this solar system. To date Uranus has not been visited again by a human spacecraft, many of it’s secrets are yet to be discovered or solved.

Simon 🙂

Solar System Exploration – Saturn

saturn voy 3

Moving away from Jupiter, our next visitor is Saturn. Saturn is twice the distance from the sun than Jupiter is, so there is a long, cold gap between the two worlds. This isn’t surprising as the gravitational pull of these two planets would either capture or knock away any other object of any substantial mass. As much as Jupiter is the king of the solar system, Saturn is the queen. It’s iconic rings sitting like a crown around it in a way not seen on any planet in the solar system.

Facts about Saturn

Some of the key facts about Saturn and how it compares with Earth:

  • Diameter 124,000km (9 x Earth’s)
  • 1 Saturn Day = 10h 42m hours long.
  • 1 Saturn year = 29 years.
  • Atmosphere = 96% Hydrogen, 3.2% Helium.
  • Volume = 763 times that of Earth.
  • Distance from the Sun = 10 x further than Earth.
  • Saturn has 62 named moons with un-numberable more smaller satellites.
  • Mas is over 95 x  Earths mass  (This is not as dense as Earth when considering it’s volume)




Many of Saturn’s 62 moons are less than 20 km in diameter, there is evidence to suggest that there are many large moons in Saturn’s rings that are yet to be discovered. Looking in close detail at four of Saturns moons we find they are different world on a very cold theme.


saturn - titan

Titan was the largest of Saturn’s moons, it was discovered by Christiaan Hyguens in 1655 and was the first to be discovered. It wasn’t named until 1847 however when John Herschel (Son of William Herschel – who discovered Uranus) published an extract on Saturn’s moons.

With a diameter 5,150km  Titan is larger than Mercury, however not as massive. Titan is the only known moon in the solar system to have a thick atmosphere. Visual examinations of Titan have not yielded any information on Titan’s surface, only with radar scanning from the Cassini – Hyguens probe in 2004 that any surface details were known. It’s atmosphere is a thick soup of 98% Hydrogen and 1.6% Methane. Information from the Cassini probe suggests that there are Methane lakes on Titan and  that the thick atmosphere could be a primordial soup that could harbour or create life if the conditions permit.



saturn - Rhea

Rhea was discovered in 1672 by Giovanni Domenico Cassini, however was not named until  1847 again by John Herschel . Rhea is an Icy world, made up from around 75% ice and 25% rock.

It is suggested that Rhea may have a ring system that isn’t easy observed. The data is unclear, but if it was so  Rhea would be the only known moon in the solar system to have a ring system.


saturn - Enclaedus

Enceladus was discovered in 1789 by William Herschel, little was know about this moon until the space age as it’s only 500km in diameter and observations were limited due to glare from Saturn. It was only until the space age that this small moon became far more interesting.

Enceladus is a world of frozen water, with a mix of new and old surfaces. The old oles marked with craters and the new surfaces smooth with huge cracks separating them.

Water volcanoes have been seen shooting water into space at immense speed, Cassini as been studying them and it’s now known that Saturn’s E ring had been created almost completely from the ejected matter from Enceladus.





Mimas had to be included in this little summary of Saturn’s moons. Yes, it is a moon and not a space station. That is all that needs to be said. A massive impact on Mimas in it’s history has created a feature that makes it look very much like the Death Star from Star Wars. It is however made from water and and rock and will not destroy planets.


Holst – Saturn

 Holst’s Saturn inspired musical piece for me definitely reflects a world that’s distant, cold and mighty. It has tunes that chill and inspire, it captures the sense of magnificence and beauty of Saturn



Recent Events

A number of probes have visited Saturn, Pioneer 10 was the first in 1979. In 1980 Voyager taking the first high definition pictures of the Saturn and some of its moons. Saturn’ s gravity flung the Voyager probe out of the plane of the solar system and out towards the stars.

Voyager 2 flew past in 1981 and made more measurements and took more pictures on its flyby, this time Saturn’s gravity was used to send Voyager 2 on towards Uranus.

Artist's Concept of Voyager
Artist’s concept of Voyager in flight.


In 2004 the Cassini-Hyguens probe entered orbit around Saturn and began collecting data on Saturn and it’s moons. Titan was of particular interest and in December 2004 Cassini released the Hyguens probe into Titans atmosphere.


It collected data on the atmosphere for several hours before it landed. It contained to send data for 90 minutes after it landed. Hyguens is so far the most distant human object to have landed on another world.



Since 2004 Cassini has been passing by Saturn and it’s moons, finding out more and more about this mysterious world and it’s system of moons, how the rings were formed and what the moons are made of. One of the stark discoveries is that water seems to have been in good supply, the solar system seems in fact to have been soaked in water in it’s past. This is evident when examining Rhea and Enceladus in particular.


More to come on this series as we move onto Uranus, I’m always keen to hear feedback from you all on this, if I’ve missed anything or something is wrong let me know.

Simon 🙂

Solar System Exploration – Jupiter


Moving away from the rocky planets of the inner solar system the first planet in this region is the king of the planets – Jupiter. This is especially fitting as Juno has just entered orbit of Jupiter at the start of it’s mission to find out more about this giant. Veiled in colourful clouds of hydrogen and Helium it is the largest and the most vivid of all the gas giants. With 67 known moons in stable orbits, Jupiter has the largest amount of moons of any planet in the solar system and with rings only discovered in the 1970’s too there is so much to Jupiter that it will be impossible to cover it all in this piece.

Facts about Jupiter


Some of the key facts about Jupiter and how it compares with Earth:

  • Diameter 139,800km (11 x Earth’s)
  • 1 Jupiter Day = 9 hours long.
  • 1 Jupiter year = 12 years.
  • Atmosphere = 75% Hydrogen, 25% Helium.
  • Volume = 1,300 times that of Earth.
  • Distance from the Sun = 5.4 x further than Earth.
  • Jupiter has 67 moons.
  • Three Earth’s could fit into the ‘Great Red Spot’.
  • Mas is over 317 x  Earths mass  (This is not as dense as Earth when considering it’s volume)




Because there are so many moons hurtling around Jupiter, covering them all is better served by looking at this link on Wikipedia on Jupiter’s moons:

Moons of Jupiter

There are the four major Galilean moons, discovered by Galileo (hence the names). These are the four largest moons that are visible with an ordinary pair of binoculars or a small telescope. Despite their similar locations, these worlds could not be more different.


True-color image taken by the Galileo orbiter

IO is the most volcanic worlds in the solar system. IO’s surface is a barren sulfur rich surface, spewed from more than 400 volcanoes all over the moon. The  are generated from the kneading effect Jupiter’s gravity has on the small world.




Europa, which is about the size of our moon has the smoothest surface of any known object in the solar system. It’s makeup is thought to be made of Nickel and Iron, but it’s the frozen water surface that has intrigued scientists for years. The frozen surface it expected to hide a sub surface ocean which could harbour life.

It’s surface is almost crater less, implying that it’s surface is frequently changing and re-freezing in order to keep it’s smooth nature. The surface is criss-crossed with giant ice cracks .



True-color image taken by the Galileo orbiter

Ganymede is the largest of Jupiter’s moons and is the only moon to have a magnetosphere. It has a roughly equal silicate rock / water ice makeup. It’s larger than Mercury, but with less mass. The origins of the lighter regions seen on Ganymede are unknown, but are suspected to be the result of tectonic activity.




Calliso is a moon made mostly of rock and ice, with little evidence of geologic activity on it’s thought it’s surface has been made completely from impacts of other objects. Callisto is the third largest moon in the solar system and Jupiter’s second largest moon.



Holst’s musical inspiration for Jupiter, is big, loud, bold and Jovial. Exactly fitting for the king of our planets.

Holst – Jupiter



Recent Events

An artist’s impression of the Juno spacecraft approaching Jupiter.


Yesterday on the 4th of July 2016 Juno arrived at Jupiter and entered obit around the planet. It’s going to be taking measurements to find out more about what the planet is made of, this is going to give us clue to how the planet was formed. Currently several theories present about the planets format, data from Juno should help us pick one, or come up with another theory.

Juno – What do we hope to learn?


Jupiter has been visited a number of times with unmanned probes, the pioneer missions being the first, with Voyagers 1 and 2 following after and giving us far more data about the planet and it’s moos, also discovering the Jupiter is a planet with rings.

jupiter rings

Since then, Cassini has flown past on the way to Saturn New Horizons also paid Jupiter a fleeting visit on it’s way to Pluto. The only mission to orbit Jupiter is the Galileo, which orbited Jupiter for seven years and gathers data on it’s atmosphere and moons before being deliberately aimed into the Jovian atmosphere, gathering a wealth of data before being crushed and vaporised by the intense pressure and heat.


Hubble has also bee able to gather data on Jupiter, these images showing the amazing detail Hubble can bring us of the planets by itself.

Keep an eye out for Jupiter on Juno – also they’re opening much of Juno’s camera to the public, enabling them to take and colour correct the pictures that they capture. This means space exploration is getting interactive and Jupiter is going to be more interesting.

Simon 🙂

No ownership claimed on images or materials – Credit – NASA

Solar System Exploration – Asteroid Belt and Ceres

The asteroid belt is a region that exists between the orbits of Mars and Jupiter where a high number of asteroids have settled in their own orbits around the sun. There are hundreds of thousands of asteroids in this region, ranging in size from the dwarf planet Ceres down to a dust particle.


Facts about the Asteroid Belt

Unlike the images of a dense region of rock as shown in science fiction, these asteroids in this region are spaced far apart. If we were to imagine travelling in this region in a spacecraft it would be difficult to hit an object without deliberately aiming for it. The total mass of material in the asteroid belt is estimated to be about 4% of the mass of the moon.

Credit: Wikipedia –


Prominent Objects in the Asteroid Belt

The most prominent objects in this region are Ceres, Vesta, Palla and Hygiea. These four bodies make up for half the mass of the asteroid belt. Ceres itself being the biggest being made up of around a third of the total mass.

Credit: Wikipedia –

The chart clearly shows the mass that the main objects in the Asteroid belt as a part of the total mass.


Ceres - RC3 - Haulani Crater (22381131691) (cropped).jpg


Ceres is 587 miles (947 kilometers) across and is comprised of rock and ice. Being the largest object in the asteroid belt, Ceres makes up about 1/3 of the total mass of the asteroid be belt. Ceres is the only object in the asteroid belt to be rounded by it’s oven gravity. It’s generally know that Ceres is made up of rock and ice, it’s makeup has highlighted that the difference between asteroids an comets is not as dissimilar as once thought.

Ceres was discovered in 1801 and was originally designated as a planet, until other similar sized objects were discovered in the region. The name Ceres comes from the Roman God of agriculture.


Vesta rgb 20110724 0835.png

Vesta has a mean diameter of 326 miles (525 kilometers) and is irregularly shaped.  Vesta’s mass makes up about 9% of the total mass of the asteroid belt.

Vesta was discovered in 1807 and is named after the virgin Goddess of home and heart in Roman mythology.




Pallas is the third largest object in the asteroid belt, with a mean diameter of 318 miles (512 kilometers) it’s mass makes up for about 7% of the total mass of the asteroid belt. It is thought that Pallas is a proto-planet – the embryo of a planet that didn’t continue to form.

Pallas was discovered in 1802 and is named after Athena, Pallas is an alternative name sometimes used for Athena. Some stories say she took them name from a friend that she killed.



Hygiea is the fourth largest object in the asteroid belt, it’s irregular shape put’s it’s diameter at somewhere between 200-300 miles (350-500 kilometers) and makes up about 2.9% of the total mass of the asteroid belt.

Hygiea was discovered in 1849 and named after Hygieia the Greek Goddess of health.


Recent Events

In September 2007 the Dawn mission was launched in order to carry out observations on Vesta and Ceres. The mission was the first to visit two non-planetary objects. In order to be able to have the power to visit these two asteroids it uses a highly efficient ion drive to propel it.

Artists impression of Dawn over Vesta

In 2011 Dawn entered orbit around Vesta and carried out observations for a year. Dawn made discoveries about two massive asteroid impacts on Vesta, that damaged it’s interior and crumpled part of it’s surface and also about dark, carbon rich material observed on Vesta.

In 2012 the Vesta phase of the Dawn mission ended before proceeding to the second part of the mission – Ceres.

In March 2015 Dawn entered orbit around Ceres, but even before it arrived there one feature on Ceres was shining out to us – literally. Two bright spots shining out from with a crater named Occator. From a distance it looks like two bright shining lights are beaming out from the surface, theories bounced around about what these spots could be and certainly they’re tantalising as they are in stark contrast to the otherwise dusty grey surface.

Spots clearly visible as Dawn approaches Ceres

Dawns mission to Ceres’ has been dominated by finding out more about these spots and has been getting closer and closer to the surface to try and find the answers.

ceres crater 1
Occator Crater on Ceres showing bright spots

It is now thought that the white material is sodium carbonate, brought up to the surface by some kind of hydrothermal activity. This puts the possibility of water or water ice beneath the surface of Ceres and that the core may be hotter than originally thought.

What next for Dawn though? Dawn is likely to remain a permanent satellite of Ceres due to it’s highly stable orbit. But there is the possibility that the mission could be extended and a flyby of a third object such as Pallas could be carried out.

What is clear from the Dawn mission is the difference between asteroids and comets is less clear and of course even seemingly boring old asteroids hold secrets of great interest. Although they’ve not yet found huge spaceship eating worms!

Simon Farnell

No ownership claimed on images or material – Credit NASA & Wikipedia

Solar System Exploration – Mars


Our next stopping place in the solar system is Mars. Mars is named after the Roman God of War, it’s also called the Red planet after it’s distinct red colour, which can be made out – even to the naked eye! It’s a terrestrial planet with some similarities to Earth, for example it’s relatively temperate, liquid water exists on the planet and the presence of two permanent ice caps at it’s poles.

Facts about Mars

  • Diameter: 6,752km (0.533 x Earth’s).
  • Mass: 0.107 x Earth.
  • 1 Mars day = 24hrs 40mins
  • 1 Mars year = 687 Days
  • Mars has two small moons.
  • Mars atmosphere consists 96% Carbon Dioxide with traces of Argon, Nitrogen, Oxygen and Water vapour.
  • The high iron ore content of the rocks and soil is to blame for Mars distinct red colour.



Mars has two small moons Phobos and Diemos, these moons are thought to be asteroids captured in Mars gravity rather than being left overs from the planets formation. Not much is known about these worlds and no probes have managed to successfully land on either moons, although this has been attempted with the Soviet Phobos missions                Phobos 1  failed en route to Mars, Phobos 2 made it to Mars but contact was lost after it achieved Mars orbit.

Phobos is names after the Greek God Phobos son of Ares (Mars) and personified fear. Diemos was the twin bother of Phobos and personified terror.




With Mars being named after a God of War there was a lot to inspire Holst when he created his piece for Mars. This is arguable the best of the Planets pieces that he composed and with it’s powerful and dark theme is definitely war like and timeless.

Recent Events

Of all the planets, Mars is probably the planet most visited by our probes and is most explored. Our fascination with the red planet and our unwavering belief that there is some kind of life on Mars keeps us going back. It’s likely that a manned mission to Mars will happen withing my lifetime – I certainly hope so, because it’s this adventure that will inspire people of all ages to re-connect with exploration and to start wondering again.

mars 3

But at this time there are five spacecraft orbiting Mars (2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN and Mars Orbiter Mission) and two on the surface (Mars Exploration RoverOpportunity and the Mars Science Laboratory Curiosity).

At this time there are no other planets with as much activity around or on them and the only other object in the solar system with an object on it which is operation is a comet. This all means that we’able to get stunning images of Mars surface and sample the soil for chemistry and signs of life – even bacteria.




Other (spooky) stuff:

With the human race so keen to find life on Mars it can only be imagined the kind of excitement caused when Viking 1 captured the picture of what seems to be a human face on Mars when it was looking for a landing site for the lander on July 25th 1976 (Picture on the right).



More recent pictures such as the one taken in 2001 show a much less spooky image of the rock formation. But even if we don’t think it’s a face – it seems to be a very regular formation. This formation has in the past and still causes debate on how natural it is and what it could really be or mean.

The surface of Mars is rocky, sandy and very inhospitable as these images show.

But even though this planet is millions of miles away, many say they feel the surface looks familiar somehow, this could be that it looks like any arid desert on Earth. But many of the surface features are familiar and wouldn’t look out of place on Earth.


Whether there is life on Mars or not, whether there is a mans face on Mars or not, the red planet will continue to be an object of curiosity. Mars will almost certainly be the base for our fist colony outside of Earth, with scientists thinking about how to make Mars habitable.

The only real question is this – when will a human set foot on Mars?

Simon 🙂

Solar System Exploration – Earth


Our exploration of the Solar system moves away from the fiery inner solar system to find a blue planet in the more temperate climes of space – we find our own planet Earth.

Earth was not named after Greek and Roman Gods and Goddesses like other planets and moons in the solar system. Instead the name Earth is of English / German origin and simply means ground. Other names used is the Greek word Gaia and the Latin Terra.

Earth is the densest planet in the solar system and has the largest moon compared to it’s size. The moon’s gravity pull affect the Earth as it passes around us. The most notable effect are the rising and falling sea levels with the tide. But it’s not hard to imagine that’s it’s pull kneads the Earth’s surface a little.

Facts about Earth

  • Earth completes and orbit one rotation (one day) every 23 hours, 56 minutes and 4 seconds.
  • Earth is travelling at 66,000 miles per hours to orbit the Sun once every 365 days 5 hours, 48 minutes and 56 seconds.
  • Earth has a dense atmosphere comprising of 78% Nitrogen, 21% Oxygen and 1% other stuff.
  • Earth is 93,000,000 (93 million) miles away from the sun. This distance is known as an AU (Astronomical Unit) used to define the distance of objects from the Sun.
  • Earth is the only object in the solar system known to harbour life (at this time common knowledge is that Earth is the only object in the Universe known to hrbor life).


Holst wasn’t kind enough to have composed me a piece on Earth. This is a bad thing in a way – but it also means that a piece for Earth is yet to be composed. But for now, Thomas Bergersons’s Creation of Earth is an amazing place to start:


With this to inspire us… only our imagination is the limit:


Missions to Earth

It’s often been said that we know more about other planets than we do about Earth, particularly it’s deep and mysterious oceans. What human kind has been doing over the last decades is finding out about this planet of ours, how it works and how we work when we’re away from it.

The space shuttle took us those first steps towards frequent, long periods of time in space in Earth’s orbit. Sadly the poor shuttle is no longer used instead opting for cheaper craft that have a single use that take us to the International Space Station (ISS) a station the size of a football field, orbiting the Earth constantly helping us find out how we’re going to expand beyond our mother planet.



Earth landscape

Earth’s landscapes have been formed by water, wind, ice and every other force that can be imagined.  These pictures show some of the results of this work in action.

The Moon


Earth has it’s own single moon, the largest compared with it’s mother planet at about a quarter of the size and a sixth of Earth gravity. It’s a world where the is no atmosphere and liquid water cannot exist on it’s surface. However water ice does exist under the surface and in deep craters.

The moon’s day is the same amount of time as it takes to orbit the Earth. This means that the Moon is tidally locked to the Earth – we can only see one side of the Moon from the Earth. It has only been since space exploration that we have seen the far side of the Moon.


The Moon has been the focus of mankind for thousands of years, our desire to find out what the Moon is and how we can get there has obsessed us. During the late 1960’s and early 1970’s several manned missions were launched and were successful in gathering Moon rock and carrying out experiments.

The Moon remains a serious focus for our exploration of the stars. Launching object from the Moon will require much less energy than from the Earth. The first Moon base was recently  proposed, rather than being based on the surface, it’s thought it could be an orbital station, controlling rovers and other equipment remotely.


It’s concept is similar to ISS but likely to be smaller and cheaper to make the huge running cost more viable. Whatever happens in the end – the Moon is going to play a big part of our journey towards the stars.

No ownership claimed on materials or pictures – Credit to NASA and other owners.

Simon 🙂


A little more for you… because I’m kind like that!

More on Earth…

Solar System Exploration – Venus

venus 1

Moving in the right direction this time, away from the Sun our next major object in the solar system is Venus.

Venus is on eof the four roacky planets in the solar sytem, it is the second planet away from the Sun and is the closest planet in size to the Earth. Venus has orbits the Sun once every 224 days and it rotates on it’s axis one every 243 days. The roation period is the longest of any planet in the solar system and it rotates in the opposite direction of any other planet. Venus was named after the Roman God of love and beauty, this is perhaps becasue it is the second brightest natural object in the night sky (the brightest being the moon).

Facts about Venus

File:Venus, Earth size comparison.jpg

Venus, Earth size comparison (Image from Wikipedia,_Earth_size_comparison.jpg)

  • Diameter: 12,100km
  • Mass: 0.815 x Earth
  • Venus is an actively volcanic world, it’s surface cannot be seen directly as it it hidden by clouds of Sulfur and Carbon Dioxide.
  • Venus Atmoshperic Pressure is 92 times Earth’s pressure – if you stood on the surface you would be instantly crushed.
  • Venus has no moon.

Just like Mercury, Venus orbits the sun within the orbit of the Earth is tis only visible at either dawn or dusk. It’s also possible to see cresent phases on these planets (if viewing ith through a powerful telescope) as you might see them on the moon.


Gustav Holst wrote a suite of classical music pieces on the planets. This was the piece that he wrote for Venus – the bringer of peace. As with all the pieces from Holst the music has a meaning back to the roots of the mythical God they’re named after. In this case as Venus is the God of love, love brings peace.



Recent Events

There hasn’t been a great deal going on with Venus of late. Various probes have been sent to Venus over the years. The Russians sent the Venera probes between 1964 and 1981 in order to gather data from Venus. Becasue of the thick atmosphere it had been speculated many years ago that Venus could harbour a rich, warm and paradise like eco system. The Venera probes quickly dispelled this, showing Venus to be a rocky world, the probes didn’t last long under the intense atmospheric pressure before bering crushed.

More recently ESA had sent the Venus Express probe to find out more about the Planet. During it’s time the probe sent back data tellingus that Venus is volcanially active and in it’s final plange recorded average temperatures at the polles to eb -157°C, colder than anywhere on Earth!

This goes to show, that distance from the Sun isn’t necesarily a set in stone guide to temperatures.

I hope you’re enjoying this series, as always I look forwar to any feedback.

Simon 🙂

No ownsership claimed on images or material – Credis to NASA, ESA, original publishers and Gustav Holst.