small planet


Photo Courtesy of NASA



The smallest planet


Mercury, one of the eight planets in the Solar System; and is considered to be the smallest planet in the Solar System. Mercury is also the closest planet to the Sun which makes it uninhabitable and cannot be explored further for many astronauts and scientists alike.  Though, Mercury can be seen from the Earth and can have an orbital period of only eighty eight days; and Mercury is the fastest orbiting planet in the Solar System. Mercury was named after a Roman entity which was the fastest flying messenger.

Strangely though, Mercury doesn’t have any atmosphere in order to retain heat and as a result, the surface on the planet will go through various temperature stages.  It can range from 800 degrees F in the day, and at night, temperatures reach  -280 F.

Mercury may be the smallest planet but it does have the biggest orbital eccentricity in the Solar System.  It is said that the surface of the planet is going to be very similar to the Moon as it has many craters.  What this really means, is that the planet has been inactive for billions of years; this means there has been no signs of life in any form so it is geologically inactive.

The planet will not also have seasons as how many of the others, such as the planet Earth have.  Mercury has a locked axis really when it comes to how it moves because it will rotate but in a very special and unique way from all of the other planets found in the Solar System.  The planet will rotate 3 times for every 2 revolutions it makes when orbiting.  It will only rotate once for every 2 years – this is Mercury years and not Earth years.

Mercury can be seen from Earth because it sits on the Earth’s orbit system; and it can be seen from Earth during the evenings and some mornings. However, Mercury will not be seen from Earth at night.  Though, the planet can be seen in different ways as it goes through the orbital stages because it can be very bright when seen from Earth however, it can be difficult at times, to view the planet as it’s so close to the Sun.

The Internal Structure of Mercury

There are 3 parts to the internal structure of Mercury;

  1. The Crust.  This can be anything from 100 kilometres thick to 300 kilometres thick.
  2. The Mantle.  This is 600 kilometres thick.
  3. The Core.  This has a radius of 1800 kilometres.

Mercury is the smallest planet in the Solar System but it does have a surface such as the Earth’s because it’s rocky; though the planet is one of four terrestrial planets.  The planet is around 70 percent metallic and only 30 percent of silicate materials which is very unique in a way; and its density is very high; one of the highest in the Solar System.  The inner core will be rich in iron also.

It is said that the core to Mercury is that of a molten core; with the mantle made from silicates.

Mercury Planet
Photo Courtesy of NASA

The Surface of Mercury and the Crater Effects

The surface of Mercury is similar to the Moon.  It will be plains which are very large and mare like; and there are of course craters that stretch across the vast planet’s surface.   Though, Mercury is not well known in terms of how the other planets are with their geology; but there are many who wish to change this and learn more about the planet.

There are many craters on Mercury of course but these can range from very small and almost bowl shaped holes to impact basins which are multi ringed and can stretch hundreds of kilometres.  Though, the Mercury craters are going to be different from those found on the Moon.

The biggest and best known crater found on Mercury is the Caloris Basin.  This has a huge diameter of 1550 kilometres and this crater’s impact was powerful enough so that it causes lava to erupt.  This helped to leave a concentric ring around the crater.

The Magnetic Field of Mercury

Mercury is of course very small but it does have a good and very strong magnetic field.  It is said that the magnetic field was created from a dynamo effect which would help to circulate iron liquid core of the planet.  Though the planet’s magnetic field deflects the solar wind that surrounds the planet and as a result, it creates a magnetosphere because of the deflected solar winds.

Mercury and its magnitude are going to vary from -2.6 and 5.7.  However, it is very difficult to get to know more about the planet because of how close it is to the Sun.  The planet can in fact be lost within the glare of the Sun and as a result, it can be studied and observed for small periods of time during the morning or the evening.

It is possible to study Mercury with telescopes based on ground, on Earth; but it does only offers limited detail. Though, Mariner 10, the first spacecraft to visit the planet, helped to bring back most data known about Mercury. Though, the world famous Hubble Space Telescope can’t actually observe the planet – at all!  This cannot view any of the planet whatsoever because of how close the planet is to the Sun; this is for safety measures.

Small planet
Mosaic image / Photo courtesy of NASA

Research from Probes

Space probes have been a vital instrument used when it comes to researching the planet.  Of course, getting to the country is not going to be easy from Earth but spacecrafts have been able to reach the planet.  The trouble is that the spacecrafts reaching Mercury is hampered because of the fact that it must travel into the Sun’s gravitational well and is very dangerous which is why no human or living being has been able to step foot on the planet.  Though, that doesn’t mean to say there won’t be more exploration to the planet as more and more want to know more about the smallest planet in the Solar System.

Future Explore Missions

There are many plans for the future for the planet Mercury from the European Space Agency.  The agency is in fact planning a mission with the country of Japan to send probes up to Mercury and explore the planet deeper.  The specific purposes of this mission will be to study the magnetosphere the planet has and the other to map the planet.

This isn’t planned to launch until 2015 but the spacecraft being sent, will not reach the planet until 2019 apparently.  It is hoped this adventure will go ahead but there is still so many things unknown as yet.  If this mission does go ahead, it will be a great experience to learn more about the planet as this mission could take almost a year to complete.  The findings could be extraordinary because scientists want to discover more about the different wavelengths with gamma rays, infrared, ultraviolet and x-ray activity in space and within this planet also.


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Photo Courtesy of NASA


The Red Planet


Mars is one of the eight planets found in the Solar System and it is more commonly known as The Red Planet. The Red Planet, Mars, is actually the second smallest planet and can be found fourth places away from the Sun. When the planet was first discovered, it was named after the Roman God of War Mars but it constantly was nicknamed the Red Planet.

The reason why it is called the Red Planet is because of the many particles of iron oxide in the atmosphere especially found on the surface of the planet. The particles offer a red appearance which contributes to the name. This is the forth terrestrial planet but it does have a very weak or thin atmosphere; and the surface of the planet does have a lot of impact craters. This is very similar to those found on the Moon and they can often resemble craters of valleys, deserts, and volcanoes; though Mars is a very unusual planet.

How the Planet Rotates

Mars can have a similar type of rotational period as that of Earth.  It is quite similar with its rotation as well as its seasonal cycles that the planet has; though Mars is the home place of the Olympus Mons.  The Olympus Mons is the highest mountain range in the Solar System.

Mars has a northern hemisphere; this covers almost 40 percent of the entire planet of Mars and it is called the Borealis Basin. The Red Planet does have the Deimos Moon and the Phobos Moon; both are the only known Moons Mars has. These are very odd in shape and are quite small in size too; though it is thought that the Moons of Mars that they are captured asteroids.

Up until 1965, most people believed that Mars must have had liquid water on the surface; however, the explorer Mariner 4 was sent to make a flyby of the planet and it was found that there didn’t seem to be any liquid present on the surface.  The reason why many believed the planet had liquid water present on the planet was because of the variations of the light; and there were many dark and light areas that could be seen from Earth.  This led many to believe that there was water present on the surface.

Mars Facts
Mars Planet / Photo Courtesy of NASA

Missions to Mars

Though, Mars offers an optical illusion through the light but with many unmanned flight missions, most scientists believed that there had to have been a large scale water reserve on the planet’s surface.  Most believe this to be the case but interestingly enough, back in 2005, data was collected from the planet. This data showed the presence of what scientists believed to be huge quantities of water ice. These were found at different locations of the planet including the mid latitudes as well as the poles of the planet.

In 2007, a rover was sent to the planet which collected samples from the surface of Mars.  When those samples were sent to the Earth and tested, the chemical compounds contained water molecules.  This was a huge breakthrough for many because for years, it was thought that there couldn’t possibly be any water available on the planet.

A year later in 2008, another rover was sent which saw water ice directly found in a shallow Martian piece of soil. This is exceptional information to come from the Planet because it could mean that people could fly to the planet and in fact many countries around the world are thinking about creating new missions. However, these missions would be solely for people to fly and even live on the Red Planet.  In Netherlands, there are projects to make up a space project to send 4 people up to Mars and live there for the rest of their lives!

There are in fact 5 different spacecrafts which are all functioning.  There are 3 which are in orbit right now including the Mars Express, the Mars Reconnaissance Orbiter and the Mars Odyssey.  However, there are 2 which are currently on the surface of the planet including the Mars Science Laboratory Curiosity and the Mars Exploration Rover Opportunity.  There are other spacecrafts on the surface of the planet; however, they are no longer in use because they have served their purpose.  The Orbiter has reported that there may be flowing water possibly found during some of the warmer months on the planet.

Though, The Red Planet can be seen freely from Earth with the naked eye; and it is a wondrous site to view.


Mars is big however; it is not as big as what Earth is.  Its diameter is around half of the size of Earth’s and it is going to be less dense than that of Earth’s also.  It only has around 11 percent of mass and 15 percent of volume of the amount that Earth has.  Mars doesn’t have a large amount of density; it’s less than Earth’s and also the Planet Mercury even though it’s bigger than the planet.

Though it does have a very unique presentation to the surface which makes it look like an orange/red appearance; and it can be often mistaken for many other colours.

The red planet
Mars atmosphere /Photo Courtesy of NASA

The Internal Structure of the Red Planet and Its Surface

The structure of Mars is very much like Earth’s, even internally.  It is very dense but it has a metallic core which proves stability and a strong structure.  It does have iron and nickel mixed in with sulphur and its core is this.  It is also partial fluid which is surrounded with a silicate mantle; but this helped to form a lot of different volcanic features as well as tectonic plates.

Mars is going to be made up of minerals which contain things such as metals, silicon and oxygen also. There is no in fact hard evidence to say that the way the planet has been structured is going to have a global magnetic field.  There have been many observations which say that parts of Mars’s crust are magnetized but this is not hard known factual evidence.

It is not known whether or not life can be established on Mars.  Yes, there may not be any life found on Mars but there have been many studies to see if humans can live on Mars eventually.  Though, if this is the case, they would need oxygen suits because no planet has the same atmosphere as Earth where they can breathe free air without the necessity of an oxygen mask and suit.

Though, with many exploration studies, there have been a lot of things such as chlorine, magnesium, sodium and potassium found in the planet’s soil.  These are some nutrients which are found on Earth and these things are vital for plants to grow.  This might mean there is chance for some life to grow on Mars.  There might not be any available liquid water able to exist on the surface, this is because of the atmosphere pressure being too low; however, there is ice water available.  There is still so much unexplored on Mars.

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