With Mercury's orbital-rotational resonance ratio at and highly elliptical orbit, an observer at certain latitudes could watch the Sun rise, move directly overhead and stop, retrograde back, then proceed back on its westward track. Fly-bys by the Mariner 10 spacecraft in and '75 and recent photos from the Mercury Messenger reveal a cratered surface, marked with cliffs and ridges very much like our Moon's.
Lava flows have also been discovered. In some parts of Mercury, these lava flows have "buried" ancient scarred terrain producing a smoother surface which has not been greatly pock-marked by meteors yet. Mercury is the most dense planet in our solar system when not accounting for gravitational compression.
If you count the force of gravitational compression, then Earth is the most dense. It is believed that Mercury's dense iron core is larger than Earth's and likely compromises most of the planet itself. This would give Mercury relatively thin mantle and crust layers. Interestingly, complex radar observations found evidence of ice water on the shady side of craters on Mercury's north pole.
This could be possible, since Mercury does not tilt on its axis and therefore rotates perpendicular to the Sun. Thus, the Sun will always be at an extremely low angle at the poles. One theory of how this ice water could have been placed on Mercury is from comet residue. Mercury is the least explored "rocky" planet of our inner solar system Mercury, Venus, Earth and Mars. However it appears that Mercury holds a lot of information about how all of the terrestrial planets have evolved since the beginning times of the solar system.
Messenger should establish orbit around Mercury in March and study it for a year. Average distance from Sun: Average distance from the center of a planet to the center of the Sun. Perihelion: The point in a planet's orbit closest to the Sun. Aphelion: The point in a planet's orbit furthest from the Sun. Sodium and calcium populate the material. Burger's models revealed the prevalence of PSD in creating the planet's tail.
Speaking of comets, the wandering chunks of ice also affect the planet's atmosphere. In a separate study, Burger and his colleagues found a pattern for calcium that repeated over Mercury's short orbit. Killen and colleagues then worked to figure out what happened when Mercury plowed through the cloud of debris known as zodiacal dust that surrounds the sun. Most of the calcium could be explained by the cloud, but the team found that Comet Encke's short 3. Apparently, comet streams can have a huge, but periodic, effect.
With virtually no atmosphere, Mercury feels very little in terms of traditional weather. It does feel the presence of solar weather, with the constant ebb and flow of the solar wind bombarding its surface. The lack of atmosphere also contributes to the planet's wild temperature extremes. On other planets, the atmosphere functions as a blanket, helping to redistribute heat somewhat.
The temperatures and solar radiation that characterize this planet are most likely too extreme for organisms to adapt to. If Earth were the size of a nickel, Mercury would be about as big as a blueberry. From an average distance of 36 million miles 58 million kilometers , Mercury is 0. One astronomical unit abbreviated as AU , is the distance from the Sun to Earth. From this distance, it takes sunlight 3. Mercury's highly eccentric, egg-shaped orbit takes the planet as close as 29 million miles 47 million kilometers and as far as 43 million miles 70 million kilometers from the Sun.
It speeds around the Sun every 88 days, traveling through space at nearly 29 miles 47 kilometers per second, faster than any other planet. Mercury spins slowly on its axis and completes one rotation every 59 Earth days. But when Mercury is moving fastest in its elliptical orbit around the Sun and it is closest to the Sun , each rotation is not accompanied by sunrise and sunset like it is on most other planets.
The morning Sun appears to rise briefly, set, and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset for other parts of the surface. One Mercury solar day one full day-night cycle equals Earth days — just over two years on Mercury. Mercury's axis of rotation is tilted just 2 degrees with respect to the plane of its orbit around the Sun. That means it spins nearly perfectly upright and so does not experience seasons as many other planets do.
Mercury formed about 4. Like its fellow terrestrial planets, Mercury has a central core, a rocky mantle, and a solid crust. Mercury is the second densest planet, after Earth.
It has a large metallic core with a radius of about 1, miles 2, kilometers , about 85 percent of the planet's radius. As the core cools, it solidifies, reducing the planet's volume and causing it to shrink. The process crumpled the surface, creating lobe-shaped scarps or cliffs, some hundreds of miles long and soaring up to a mile high, as well as Mercury's " Great Valley ," which at about miles long, miles wide and 2 miles deep 1, by by 3.
Indeed, a study of cliffs on Mercury's surface suggested the planet may still rumble with earthquakes, or "Mercuryquakes. However, another study suggested Mercury's volcano eruptions likely ended about 3. One study suggested that Mercury's surface features can generally be divided into two groups — one consisting of older material that melted at higher pressures at the core-mantle boundary, and the other of newer material that formed closer to Mercury's surface. Another study found that the dark hue of Mercury's surface is due to carbon.
This carbon wasn't deposited by impacting comets, as some researchers suspected — instead, it may be a remnant of the planet's primordial crust. A completely unexpected discovery made by Mariner 10 was that Mercury possessed a magnetic field.
Planets theoretically generate magnetic fields only if they spin quickly and possess a molten core. But Mercury takes 59 days to rotate and is so small — just roughly one-third Earth's size — that its core should have cooled off long ago.
An unusual interior could help to explain the differences in Mercury's magnetic field when compared to Earth. Russell co-authored a model that suggests that Mercury's iron core may be turning from liquid to solid at the core's outer boundary rather than the inner. The discovery in by Earth-based radar observations that Mercury's core may still be molten could help explain its magnetism, though the solar wind may play a role in dampening the planet's magnetic field.
The magnetic field in the solar wind — the charged particles streaming off the sun — periodically touches upon Mercury's field, creating powerful magnetic tornadoes that channel the fast, hot plasma of the solar wind down to the planet's surface.
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