Mercury

Mercury

Image: NASA/ MESSENGER
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

      The planet Mercury was named by the Romans after Mercury meaning 'The Messenger to the Gods'. Mercury is the first planet from the sun. It is also the smallest planet in our solar system. It is one-third the size if earth. Mercury having no satellites, is the planet having the greatest temperature in our solar system. Thirteen times a century, Mercury passes directly between the Earth and the Sun. Space shuttles Mariner 10 and MESSENGER visited Mercury. MESSENGER stands for MErcury Surface, Space Environment, GEochemistry and   

Ranging.

How it got it's shape

    

Volcanoes in Mercury
image: www.universetoday.com

 Mercury has been shaped by three processes:

1: impact cratering where large objects struck the surface

2: volcanism where lava flooded the surface

3: tectonic activity

Timeline

Galileo Galilei
Image: www.wikipedia.org

c385BC  : Heracleides (a Greek astronomer) became the first person to suggest that Mercury orbits the Sun

1610       : Galileo (an Italian astronomer) made the first telescopic observation of Mercury. 

1631       : Pierre Gassendi (a French astronomer) made the first telescopic observation of the transit of Mercury across the face of the sun.

Atmosphere

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     Mercury's atmosphere is like the outermost layer of the Earth's atmosphere (which is Exosphere), most of it's atoms and molecules are lost into space. Mercury has a thin atmosphere of composed Helium and Sodium. Mercury's atmosphere is so thin that there is nothing to stop meteors from crashing into it's surface. It's atmosphere is too thin to provide insulation and thus, in day time, it's temperature reaches 425°C (hot enough to melt tin) while in the night time, it drops to -170°C. Mercury has small ice caps at it's north and south poles but the ice is not made from water. It is made from acid. Mercury's atmosphere contains Potassium, sodium, oxygen, argon, helium, nitrogen and hydrogen.

Physical data

Distance from the sun: 57,909,175 km

Orbital period: 88 Earth days

Rotational period: 58.6 Earth days

Mercury completes three rotations for every two orbits around the sun.

Diameter: 4,878 km (approximately 40% of Earth's)

Circumference: 15, 329 km

Surface area: 74,800, 000 km

Mass: 3.30 x 1023 Kg (If Earth was the size of a baseball, Mercury would be the size of a golf ball)

Volume: 6.1 x 1010 Km3 (approximately 5% of Earth's)

Density: 5.4 g/cm3

Surface gravity: 3.7 m/s2

Atmosphere: Potassium, sodium, oxygen, argon, helium, nitrogen, hydrogen

Atmosphere: trace (1.03Kg/cm3 on Earth)

References

Big Book of Knowledge by Paragon/ page 104, 308

Ultimate Guide to Stars and Planets by Paragon/ page 32 to 37

Tell Me About by Chancellor Press/ page 191