Planet Mercury. Yibran Perez.Devon Lyle, Draven Soto

Mercury At a Glance.  Mercury is the closest planet to the Sun and due to its proximity it is not easily seen except during twilight. For every two orbits of the Sun, Mercury completes three rotations about its axis and up until 1965 it was thought that the same side of Mercury constantly faced the Sun. Thirteen times a century Mercury can be observed from the Earth passing across the face of the Sun in an event called a transit, the next will occur on the 9th May 2016.

Planet Profile.  For its small size, mercury has a mass of 330,104,000,000,000 billion kg (0.055 x Earth).  Orbital period is only 88 earth days.  Unlike other planets, mercury has no know moons.  For being the planet closest to the sun, its not the hottest. Daytime temperatures reach 427 C(800 F). At night time, temperatures decrease to -173 C(-279 F).  Discovered in 14 th century BC by Assyrian astronomers.

Quick Comparison.

Outter Mercury.  Mercury has just 38% the gravity of Earth, this is too little to hold on to what atmosphere it has which is blown away by solar winds. However while gases escape into space they are constantly being replenished at the same time by the same solar winds, radioactive decay and dust caused by micrometeorites.

Outter Mercury Cont.  Mercury's atmosphere contains small amounts of hydrogen, helium, and oxygen. It also has even tinier amounts of sodium, potassium, calcium, and magnesium. Some of the gas particles come from the solar wind. Others are made by radioactive decay or when micrometeorites smash into the surface.

Inner Mercury.  Scientists believe that the interior structure of Mercury includes a metallic core, an intermediate rocky layer, and a thin brittle crust. The composition of Mercury is probably high in iron, although surface features indicate that volcanic activity once existed at the surface. There is little evidence of motions near the surface of the planet now, although at earlier times during Mercury's evolution the surface was much more active. We know relatively little about Mercury, compared to most of the other planets, because it is relatively difficult to see and only one spacecraft has studied the planet.

Inner Mercury Conti.  As noted previously, the density of Mercury and the magnetic field suggest geological differentiation and a large iron core. In the case of the Earth the metallic core occupies about 16% of the interior by volume and in the case of the Moon the core occupies about 4% by volume. In the case of Mercury the core is thought to occupy about 50% of the interior by volume (and a whopping 70% by mass). Thus, Mercury is a planet with a very large iron core and a comparatively thin mantle compared with the Earth.

Surface Of Mercury.  There are three major types of surface features on Mercury:  Smooth plains that resemble Lunar maria.  Intercrater plains, which are pocked with small craters and occupy about 70% of the surface that we have examined.  Rugged highlands that bear some resemblance to the corresponding regions on the Moon.  The adjacent image shows a mosaic of photographs taken from Mariner 10 in 1974 that summarizes the character of the surface.

History.  In Roman mythology Mercury is the god of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes, the messenger of the Gods. The planet probably received this name because it moves so quickly across the sky. Mercury has been known since at least the time of the Sumerians (3rd millennium BC). It was sometimes given separate names for its apparitions as a morning star and as an evening star. Greek astronomers knew, however, that the two names referred to the same body. Heraclitus even believed that Mercury and Venus orbit the Sun, not the Earth.

Visitations.  Mercury has been now been visited by two spacecraft, Mariner 10 and MESSENGER. Marriner 10 flew by three times in 1974 and Only 45% of the surface was mapped (and, unfortunately, it is too close to the Sun to be safely imaged by HST). MESSENGER was launched by NASA in 2004 and has been in orbit Mercury since Its first flyby in Jan 2008 provided new high quality images of some of the terrain not seen by Mariner 10. Since then Messenger has taken over 250,000 photographs coving the entire planet.

Interesting Facts.  Mercury has no atmosphere and no known satellites, perhaps because of its proximity to the Sun.  A day, from sunrise to sunrise, on Mercury is equivalent to 176 Earth Days.  Mercury is known as a terrestrial planet consisting of about 70% metallic and 30% silicate material.  The surface of the planet is covered in craters much like those seen on Earth’s moon. This is a sign that Mercury has been geologically dormant for billions of years.  Since Mercury’s orbit is within Earth’s orbit, it can be viewed from Earth in the early morning or the late evening, but never in the middle of the nighttime.  Mercury is the second densest planet after Earth.  The Hubble Space Telescope cannot view Mercury. This is because Mercury is too close to the Sun and the brightness would harm the electrical components of the telescope.

Interesting Facts Cont.  Mercury has water ice and organics.This may sound surprising given that the planet is so close to the Sun, but the ice is in permanently shadowed craters that don’t receive any sunlight.  The water ice appears younger than we would expect.Close examination of the ice shows sharp boundaries, which implies that it wasn’t deposited that long ago; if it was, the ice would be somewhat eroded and mixed in with Mercury’s regolith surface. This Image is a forced perspective of mercury north pole.

Video. 