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PLANET MARS

Mars' History & Naming 

Mars is named after the ancient Roman god of war, as befitting the red planet's bloody color. The Romans

copied the ancient Greeks, who named the fourth planet from the sun after their god of war, Ares. Other civilizations also typically gave the planet names based on its color  — for example, the Egyptians named it

"Her Desher ," meaning "the red one," while ancient Chinese astronomers dubbed it "the fire star." 

The Moons of Mars 

The two moons of Mars, Phobos and Deimos were discovered by American astronomer Asaph Hall over thecourse of a week in 1877. Hall had almost given up his search for a moon of Mars, but his wife Angelina urged

him on —  he discovered Deimos the next night, and Phobos six days after that. He named the moons after the

sons of the Greek war god Ares — Phobos means "fear," while Deimos means "rout." Both Phobos and Deimos

are apparently made of carbon-rich rock mixed with ice and are covered in dust and loose rocks. They are tinynext to Earth's moon, and are irregularly shaped, since they lack enough gravity to  pull themselves into a more

circular form. The widest Phobos gets is about 17 miles (27 kilometers), and the widest Deimos gets is roughly

nine miles (15 kilometers). Both moons are pockmarked with craters from meteor impacts. The surface of Phobos also possesses an intricate pattern of grooves, which may be cracks that formed after the impact created

the moon's largest crater   — a hole about 6 miles (10 kilometers) wide, or nearly half the width of Phobos. They

always show the same face to Mars, just as our moon does to Earth. It remains uncertain how Phobos andDeimos were born. They might have been asteroids captured by Mars' gravitational pull, or they might have

 been formed in orbit around Mars the same time the planet came into existence. Phobos is gradually spiraling

toward Mars, drawing about 6 feet (1.8 meters) closer to the red planet each century. Within 50 million years,

Phobos will either  smash into Mars or break up and form a ring of debris around the planet.

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Research & Exploration 

The first person to watch Mars with a telescope was Galileo, and in the century after him, astronomers

discovered its polar ice caps. In the 19th and 20th centuries, researchers believed they saw a network of long,

straight canals on Mars, hinting at civilization, although later these often proved to be mistaken interpretations

of dark regions they saw. Robot spacecraft began observing Mars in the 1960s, with the United States launchingMariner 4 there in 1964 and Mariners 6 and 7 in 1969. They revealed Mars to be a barren world, without any

signs of the life or civilizations people had imagined there. In 1971, Mariner 9 orbited Mars, mapping about 80 percent of the planet and discovering its volcanoes and canyons. NASA's Viking 1 lander  touched down onto

the surface of Mars in 1976, the first successful landing onto the Red Planet. It took the first close-up pictures ofthe Martian surface but found no strong evidence for life. The next two craft to successfully reach Mars were

the Mars Pathfinder, a lander, and Mars Global Surveyor, an orbiter, both launched in 1996. A small robot

onboard Pathfinder named Sojourner  — the first wheeled rover to explore the surface of another planet —  ventured over the planet's surface analyzing rocks. In 2001, the United States launched the Mars Odyssey probe,

which discovered vast amount of water ice beneath the Martian surface, mostly in the upper three feet (one

meter). It remains uncertain whether more water lies underneath, since the probe cannot see water any deeper.In 2003, the closest Mars had passed to Earth in nearly 60,000 years, NASA launched two rovers, nicknamed

Spirit and Opportunity, which explored different regions of the Martian surface, and  both found signs that water

once flowed on the planet's surface. In 2008, NASA sent another mission, Phoenix, to land in the northern

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 plains of Mars and search for water, Two orbiters — NASA's Mars Reconnaissance Orbiter and ESA's Mars

Express — are keeping Mars Odyssey company over the planet. In 2011, NASA's Mars Science Laboratory

mission, with its rover named Curiosity, is scheduled to investigate Martian rocks to determine the geologic processes that created them and find out more about the present and past habitability of Mars.

Possibility of Life 

Mars could have once harbored life. Some conjecture that life might still exist there even today. A number of 

researchers have even speculated that life on Earth might have seeded Mars, or that life on Mars seeded Earth. 

The most public scientific claim for life on Mars came in 1996. Geologist David McKay at NASA's Johnson

Space Center in Houston and his colleagues focused on rocks blasted off the surface of Mars by cosmic impactsthat landed on Earth. Within they found complex organic molecules, grains of a mineral called magnetite that

can form within some kinds of bacteria, and tiny structures that resembled fossilized microbes. However, these

claims have proven controversial, and there is no consensus as to whether they are signs of life.

Mars might have possessed oceans on its surface in the past, providing an environment for life to develop.

Although the red planet is a cold desert today, researchers suggest that liquid water may be presentunderground, providing a potential refuge for any life that might still exist there.

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PLANET NEPTUNE

Neptune’s History & Naming 

The planet Neptune was discovered on Sept. 23, 1846. Neptune was the first planet to get its existence predicted

 by mathematical calculations  before it was actually seen by a telescope. Irregularities in the orbit of Uranus led

French astronomer Alexis Bouvard to suggest that the gravitational pull from another celestial body might be

responsible. German astronomer Johann Galle then relied on subsequent calculations to help spot Neptune viatelescope. In accordance with all the other planets seen in the sky, this new world was given a name from Greek

and Roman mythology —  Neptune, the Roman god of the sea.

Neptune’s Moons 

 Neptune has 13 known moons, named after lesser sea gods and nymphs from Greek mythology, just as

 Neptune itself was named after the Roman god of the sea. The largest by far is Triton, whose discovery on Oct.

10, 1846 was in a sense enabled by beer  — amateur astronomer William Lassell used the fortune he made as a

 brewer to finance his telescopes. Triton is unique in being the only large moon in the solar system to circle its planet in a direction opposite to its planet's rotation — this "retrograde orbit" suggests that Triton may once

have been a dwarf planet that Neptune captured rather than forming in place. Neptune's gravity is dragging

Triton closer to the planet, meaning that millions of years from now, Triton will come close enough for 

gravitational forces to rip it apart. Triton is extremely cold, with temperatures on its surface reaching aboutminus 391 degrees F (minus 235 degrees C), making it one of the coldest places in the solar system.

 Nevertheless, Voyager 2 detected geysers spewing icy matter upward more than 5 miles (8 kilometers),

showing its interior appears warm. Recently, seasons have been discovered on Triton. Triton is the onlyspherical moon of Neptune —  the planet’s other twelve moons are irregularly shaped. 

The Rings of Neptune 

 Neptune's unusual rings are not uniform, but possess bright thick clumps of dust called arcs. The rings arethought to be relatively young and short-lived. Earth-based observations announced in 2005 found that

 Neptune's rings are apparently far more unstable than previously thought, with some dwindling away rapidly.

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(Imke de Pater et al., "The dynamic neptunian ring arcs: evidence for a gradual disappearance of Liberté and

resonant jump of courage." Icarus, Volume 174, Issue 1, March 2005, Pages 263-272.)

Research & Exploration 

 NASA's Voyager 2 space satellite was the first and as yet only spacecraft to visit Neptune on Aug. 25, 1989.The satellite discovered Neptune's rings and six of the planet's moons  — Despina, Galatea, Larissa, Naiad,

Proteus, and Thalassa. An international team of astronomers relying on ground telescopes announced the

discovery of  five new moons orbiting Neptune in 2003.

Formation of Neptune 

 Neptune is generally thought to have formed with the initial buildup of a solid core followed by the capture of 

surrounding hydrogen and helium gas in the nebula surrounding the early sun. In this model, proto-Neptuneformed over the course of 1 to 10 million years.