Planet Mercury
Mercury It is the closest planet to the sun. As such, it circles the sun faster than all the other planets, which is why the Romans named it after their swift-footed messenger god.
The Sumerians had also known about Mercury for at least 5,000 years. It was often associated with Nabu, the god of writing.
to Mercury it was also given separate names for its appearance as a morning star and as an evening star.
Greek astronomers knew, however, that the two names referred to the same body, and Heraclitus, around 500 BC, correctly thought that both Mercury and Venus orbited the sun, not the Earth.
The physical characteristics of mercury
Because the planet is so close to the sun, Mercury’s surface temperature can reach a blistering 450 degrees Celsius (840 degrees Fahrenheit).
However, since this world has no real atmosphere to trap heat, at night temperatures can plummet to -275 F (minus 170 C), a temperature swing of more than 1,100 F (600 C), the largest in the solar system.
Mercury is the smallest planet – is only slightly larger than Earth’s moon. With no significant atmosphere to stop impacts, the planet is pockmarked with craters.
4,000 million
About 4 billion years ago, an asteroid about 100 kilometers wide struck Mercury with an impact equivalent to 1 trillion 1-megaton bombs, creating a vast impact crater about 1,550 kilometers wide.
Known as the Caloris Basin, this crater could contain the entire state of Texas. Another large impact may have helped create the planet’s strange spin.
As close to the sun as Mercury is, in 2012 NASA’s MESSENGER spacecraft discovered water ice in craters around its north pole, where regions may be permanently shadowed by the sun’s heat.
The south pole may also contain ice packs, but MESSENGER’s orbit did not allow scientists to explore the area.
Comets or meteorites may have spewed ice there, or water vapor may have spewed gases from the planet’s interior and frozen at the poles.
As if Mercury wasn’t small enough, not only did it shrink in the past, but it continues to shrink today.
The tiny planet is made up of a single continental plate on a cooling iron core.
As the core cools, it solidifies, reducing the planet’s volume and causing it to shrink.
The process wrinkled the surface, creating escarpments, or lobe-shaped cliffs, some hundreds of miles long and rising up to a mile high.
THE GREAT VALLEY
As well as Mercury’s «Great Valley,» which at some 620 miles long, 250 miles wide, and 2 miles deep (1,000 by 400 by 3.2 km) is larger than Arizona’s famous Grand Canyon and deeper. than the Great Rift Valley in East Africa.
«The young age of the small scarps means Mercury joins Earth as a tectonically active planet with new fault lines likely forming today as Mercury’s interior continues to cool and the planet contracts,» Tom said. Watters, the Smithsonian’s senior scientist at the National Air and Space Museum in Washington, DC, in a statement.
earthquakes
In fact, a 2016 study of the cliffs on Mercury’s surface suggested that the planet could still rumble with earthquakes, or «mercury quakes.» This could mean that Earth is not the only tectonically active planet, the study authors said.
Also, in the past, Mercury’s surface was constantly reshaped by volcanic activity.
However, another 2016 study suggested that Mercury’s volcanic eruptions likely ended around 3.5 billion years ago.
Mercury is the second densest planet after Earth, with a huge metallic core about 3,600 to 3,800 km (2,200 to 2,400 miles) across, or about 75 percent of the planet’s diameter.
By comparison, Mercury’s outer shell is only 500 to 600 km (300 to 400 miles) thick.
The combination of its huge nucleus and abundance of volatile elements has stumped scientists for years.
A completely unexpected discovery made by Mariner 10 was that Mercury had a magnetic field.
nuclei
Planets theoretically generate magnetic fields only if they rotate rapidly and have a molten core.
But Mercury takes 59 days to rotate and is so small – only a third the size of Earth – that its core should have cooled long ago.
«We had figured out how Earth works, and Mercury is another rocky terrestrial planet with an iron core, so we thought it would work the same way,» Christopher Russell, a professor at the University of California, Los Angeles, said in a statement.
An unusual interior could help explain differences in Mercury’s magnetic field compared to Earth’s.
MESSENGER
The MESSENGER observations revealed that the planet’s magnetic field is about three times stronger in its northern hemisphere than in its southern hemisphere.
Russell is co-author of a model that suggests that Mercury’s iron core may be turning from a liquid to a solid at the outer edge of the core, rather than its interior.
«It’s like a blizzard where snow forms at the top of the cloud and in the center of the cloud and also at the bottom of the cloud,» Russell said. «Our study of Mercury’s magnetic field indicates that iron is snowing through this fluid that feeds Mercury’s magnetic field.»
The discovery in 2007 by ground-based radar observations that Mercury’s core may still be molten could help explain its magnetism, although the solar wind could play a role in damping the planet’s magnetic field.
Magnetic field
Although Mercury’s magnetic field is only 1 percent of Earth’s strength, it is very active.
The magnetic field in the solar wind—charged particles streaming from the sun—periodically touches Mercury’s field, creating powerful magnetic tornadoes that funnel the fast-moving, hot plasma of the solar wind toward the planet’s surface.
Instead of a substantial atmosphere, Mercury possesses an ultrathin «exosphere» made up of atoms that are ejected from its surface by solar radiation, the solar wind, and micrometeoroid impacts. These quickly escape into space, forming a tail of particles.
A 2016 study suggested that Mercury’s surface features can generally be divided into two groups – one consisting of older material melting at higher pressures at the core-mantle boundary, and the other consisting of newer material that forms closer to Mercury’s surface.
Another 2016 study found that the dark hue of Mercury’s surface is due to carbon.
This carbon was not deposited by impact comets, as some researchers suspected, but may instead be a remnant of the planet’s primordial crust.
The orbital characteristics of Mercury
Mercury circles the sun every 88 Earth days, traveling through space at nearly 112,000 mph (180,000 km/h), faster than any other planet.
Its oval orbit is highly elliptical, taking Mercury as close as 29 million miles (47 million km) and as far as 43 million miles (70 million km) from the sun.
If one could stand on Mercury when it is closest to the sun, it would appear more than three times larger than when viewed from Earth.
Mercury orbit
Interestingly, due to Mercury’s highly elliptical orbit and the 59 Earth days it takes to rotate on its axis, when across the planet’s scorching surface, the sun appears to briefly rise, set, and rise again before traveling west to through the sky
At sunset, the sun appears to set, rise again briefly, and then set again.
In 2016, a rare transit of Mercury occurred, where the planet crossed the face of the sun. Mercury’s transit may have shed secrets on its thin atmosphere, assisted in the search for worlds around other stars, and helped NASA refine some of its instruments.
Internal structure: The iron core is approximately 3,600 to 3,800 km (2,200 to 2,400 miles) wide. Silicate outer shell approximately 500 to 600 km thick.
orbit and rotation
Average distance from the sun: 35,983,095 miles (57,909,175 km). By comparison: 0.38 Distance from Earth to Sun.Perihelion (closest approach to the sun): 28,580,000 miles (46,000,000 km). For comparison: 0.313 times that of Earth.Aphelion (farthest distance from the sun): 43,380,000 miles (69,820,000 km). For comparison: 0.459 times that of Earth.Day length: 58,646 Earth days.
research and exploration
The first spacecraft to visit Mercury was Mariner 10, which imaged about 45 percent of the surface and detected its magnetic field.
NASA’s MESSENGER orbiter was the second spacecraft to visit Mercury. When it arrived in March 2011, MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) became the first spacecraft to orbit Mercury.
The mission came to an abrupt end on April 30, 2015, when the spacecraft, which had run out of fuel, crashed into the planet’s surface.
Morocco
In 2012, scientists discovered a group of meteorites in Morocco that they believe may have originated from the planet Mercury.
If so, the rocky planet would become a member of a very select club with samples available on Earth; only the moon, Mars, and the asteroid belt have verified the presence of rocks.
In 2016, scientists published the first global digital elevation model of Mercury, combining more than 10,000 images acquired by MESSENGER to take viewers across the open spaces of the small world.
The model revealed the highest and lowest points on the planet – the highest is just south of Mercury’s equator, 4.48 km above the mean elevation of the planet.
While the lowest point is in the Rachmaninoff Basin, the presumed home to some of the most recent volcanic activity on the planet, and lies 5.38 km below the landscape average.
What is Mercury like?
Moons: 0Mass: 5.5% of EarthDiameter: 3031 milesYear: 88 Earth daysDay: 58.7 Earth daysTemperature: -300 to +800 degrees FDistance from the Sun: 1st planet from the sun, 36 million milesPlanet Type: Terrestrial (has a hard rocky surface)
Now that Pluto is no longer classified as a planet, Mercury is the smallest planet in the solar system.
Mercury has a rocky surface and a core…