News
Telescopes for Astronomy
Amazing image of Earth and the Moon taken by Messenger
24th August 2010

The image on the left is of Earth and the moon set against the vastness of space. The picture was snapped by NASA’s Messenger probe at a distance of 114 million miles (183 million km) and evokes memories of the Voyager 1 image of Earth taken from 3.7 billion miles away in 1990.

The image was taken during NASA’s search for Vulcanoids using the Messenger probe as it hurtles towards its final destination of the nearest planet to the sun, Mercury.

Vulcanoids, are asteroids that are thought to orbit between the sun and Mercury, although none have ever been discovered as yet and may not actually exist at all.

If found though they could contain material that could provide valuable clues as to how the rocky inner planets formed.

The name Vulcanoids comes from the hypothetical planet Vulcan which was at one time thought to orbit between the sun and Mercury.

The Messenger spacecraft has already had quite a journey since its launch in 2004. The probe has used both Venus and Earth as gravity assists and has already made three flybys of Mercury gathering valuable new information about the inner most planet.

Messenger will be placed in orbit around Mercury in March 2011 when it will begin a year long study of the planet.

More Stories
Surface
Mercury's surface appears to be much like that of the moon. It is covered by a thin layer of minerals called silicates in the form of tiny particles. Like the moon it has flat plains, steep cliffs and many deep craters.

Atmosphere
Mercury has very little atmosphere, only tiny amounts of helium, hydrogen, oxygen and sodium. Because of the lack of atmosphere Mercury's sky is black with stars being visible during the day.

Temperature
Mercury doesn't have enough atmosphere to protect it from the sun's rays. The temperature on the planet may reach 450C (840F) during the day but at night the temperature may drop as low as -170C (-275F). Mercury doesn't have enough atmosphere.
Moons & Origin of Name
Life on Mercury
Mercury has no moons.
The Romans named the planet after the messenger to the gods.


Scientists doubt that the planet has any form of life.


Is Mercury Just Like the Moon?
Planet Mercury
The Moon
Superficially Mercury seems very like the Moon, a long dead world with no atmosphere to speak of featuring extremely high temperatures during the day and freezing cold temperatures at night. The terrain also looks very similar, a highly cratered surface made up of a powdery grey dust. So what are the differences if any?

The first major difference is when you compare the density of the two worlds. Mercury’s density is much higher than the Moon’s and actually almost equal to Earth’s. This means that a portion of Mercury would weigh only slightly less than an equal portion of Earth. This is because Mercury has a large iron core which accounts for 40% of its volume, which brings us to the second major difference. Mercury has an active molten iron core which means that like Earth and unlike the Moon it produces its own magnetic field. The strength of the field is only around 1% of Earth’s. The third difference is that the force of gravity found on Mercury is more than twice as strong as that found on the Moon, the planet’s gravity is around two fifths of that we have on Earth. Lastly it has recently been discovered that Mercury was far more volcanically active in its early history than previously thought, much more so than the Moon. Indeed the latest evidence indicates that there may have been geological activity on Mercury up until 1 billion years ago, if this evidence is confirmed it would mean Mercury would have much younger surface features than there are on the Moon.

Mercury is one of the most mysterious planets in our solar system and we are only just learning more about it thanks to a few recent flybys by the NASA spacecraft Messenger. Once the craft is placed in orbit in 2011 new secrets will be revealed about the smallest planet in our solar system.
Planet Mercury - Images and Videos
Mercury close up
Messenger images of Mercury
"Spider" Impact crater
Spider Impact crater
Planet Mercury - Vital Statistics
Comparison with Earth
Diameter: 3,032 miles (4,880 km)
Average Distance from Sun: 36 million miles (58 million km)
Orbital Period: 88 days
Rotation Period: 59 days
Moons: 0

Maximium Surface Temperatures: 450C (840F)
Minumum Surface Temperatures: -170C (-275F)

Gravity: 3.7 m/s2 (38% Earth's Gravity)
Density: 5.427 g/cm3 (98.4% Earth's Density)
Mass: 3.3022 x 1023 kg (5.5% Earth's Mass)
Volume: 6.08272 x 1010 km3 (5.6% Earth's Volume)

Atmosphere: 42% Molecular oxygen, 29.0% sodium, 22.0% hydrogen, 6.0% helium, 0.5% potassium, Trace amounts of argon, nitrogen, carbon dioxide, water vapor, xenon, krypton and neon.
Diameter: 7,926 miles (12,756 km)
Average Distance from Sun: 93 million miles (150 million km)
Orbital Period: 365.24 days
Rotation Period: 23.934 hours
Moons: 1

Maximium Surface Temperatures: 58C (136F)
Minumum Surface Temperatures: -88C (-126F)

Gravity: 9.766 m/s2
Density: 5.515 g/cm3
Mass: 5.9737 x 1024 kg
Volume: 1.0832 x 1012 km3

Atmosphere: 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, water vapour makes up around 0.4% of Earth's atmosphere depending on climatic conditions.
Future and Past Missions to Mercury
Bepicolombo
bepicolombo Launch: August 2013
Arrival: 2019
Agency: ESA & JAXA
Two orbiters built by the ESA (Europe) and JAXA (Japan) which will hopefully gather a large range of data on its 1 year mission around Mercury.

Messenger
messenger Launch: August 2004
Arrival: March 2011
Agency: NASA
Messenger has already made 3 flybys of Mercury before it will make its orbit insertion in 2011, making a comprehensive survey of the planet.

Mariner 10
mariner 10 Launch: November 1973
Arrival: March 1974
Agency: NASA
Mariner 10 was the first spacecraft to use "gravity assist", flying close to a planet to increase speed. It made 3 flybys during 1974-75 taking 3,500 images. It is believed to be still flying past Mercury every 6 months.