My Science School

Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with thick bands of brown, yellow, and white clouds. Its atmosphere is made up of hydrogen and helium gas, just like our Sun, and if it was much more massive, it could become a star! Jupiter took shape when the rest of the solar system formed about 4.5 billion years ago, when gravity pulled swirling gas and dust in to become this gas giant. Jupiter took most of the mass left over after the formation of the Sun, ending up with more than twice the combined material of the other bodies in the solar system. In fact, Jupiter has the same ingredients as a star, but it did not grow massive enough to ignite. As a gas giant, Jupiter doesn’t have a true surface. The planet is mostly swirling gases and liquids. While a spacecraft would have nowhere to land on Jupiter, it wouldn’t be able to fly through unscathed either. The extreme pressures and temperatures deep inside the planet crush, melt and vaporize spacecraft trying to fly into the planet.

Giant planet

Jupiter is the king of solar system. It is an amazing 143,000 km (89,000 miles) wide. Jupiter is so large that all of the other planets could fit inside it! The planet is mostly made of hydrogen and helium surrounding a dense core of rocks and ice, with most of its bulk likely made up of liquid metallic hydrogen, which creates a huge magnetic field. Jupiter is visible with the naked eye and was known by the ancients. Its atmosphere consists mostly of hydrogen, helium, ammonia and methane.

Juno Mission

NASA’s Juno spacecraft is helping scientists to understand how Jupiter formed. It is orbiting closer to the gas giant than any spacecraft has before.

Juno's mission is to measure Jupiter's composition, gravity field, magnetic field, and polar magnetosphere. It will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds up to 618 kilometers per hour (384 mph).

Juno is the second spacecraft to orbit Jupiter, after the nuclear powered Galileoorbiter, which orbited from 1995 to 2003. Unlike all earlier spacecraft sent to the outer planets, Juno is powered by solar arrays, commonly used by satellites orbiting Earth and working in the inner Solar System, whereas radioisotope thermoelectric generators are commonly used for missions to the outer Solar System and beyond. For Juno, however, the three largest solar array wings ever deployed on a planetary probe play an integral role in stabilizing the spacecraft as well as generating power.

Beneath the clouds

Any spacecrafts that passed through Jupiter’s clouds would be crushed and melted by the huge pressure. Scientists believe that beneath the clouds there is a giant ocean made of liquid metal.

Jupiter’s rings

Jupiter has three thin rings, called the Jovian Rings. They are mostly made of dust and can only be seen when viewed from behind Jupiter, when they are lit up by the Sun. The main ring is flattened. It is about 20 miles (30 km) thick and more than 4,000 miles (6,400 km) wide.

The inner cloud-like ring, called the halo, is about 12,000 miles (20,000 km) thick. The halo is caused by electromagnetic forces that push grains away from the plane of the main ring. This structure extends halfway from the main ring down to the planet's cloud tops and expands. Both the main ring and halo are composed of small, dark particles of dust.

The third ring, known as the gossamer ring because of its transparency, is actually three rings of microscopic debris from three of Jupiter's moons, Amalthea, Thebe and Adrastea. It is probably made up of dust particles less than 10 microns in diameter, about the same size of the particles found in cigarette smoke, and extends to an outer edge of about 80,000 miles (129,000 km) from the center of the planet and inward to about 18,600 miles (30,000 km).

Great Red Spot

One of the Jupiter’s most famous features is the Great Red Spot. It is a huge storm, more than three times the size of Earth, that has been raging for hundreds of years!

The red colour of the Great Red Spot is thought to be caused by organic molecules, red phosphorous or other elements that come from inside Jupiter. Some theories propose that the colour is caused by reactions between these chemicals in Jupiter’s atmosphere, or by lightning striking the molecules. The colour is not always the same, either: sometimes it is dark red, while at other times it is a pale pink colour, or even white! Perhaps Jupiter’s Great Red Spot is not so red after all!

 

Picture Credit : Google

 

Between the planets Mars and Jupiter lies the asteroid belt. It is home to tens of thousands of asteroids. These rocky objects are leftovers from the early Solar System, and are too small to be considered planets. They come in different shapes and sizes with the smallest being less than 1 km (0.6 miles) wide. Some asteroids have moons and one even has rings!

Most of the asteroids in the Main Belt are made of rock and stone, but a small portion of them contain iron and nickel metals. The remaining asteroids are made up of a mix of these, along with carbon-rich materials. Some of the more distant asteroids tend to contain more ices. Although they aren't large enough to maintain an atmosphere, but there is evidence that some asteroids contain water.

Some asteroids are large, solid bodies — there are more than 16 in the belt with a diameter greater than 150 miles (240 km). The largest asteroids, Vesta, Pallas and Hygiea, are 250 miles (400 km) long and bigger. The region also contains the dwarf planet Ceres. At 590 miles (950 km) in diameter, or about a quarter of the size of our moon, Ceres is round yet is considered too small to be a full-fledged planet. However, it makes up approximately a third of the mass of the asteroid belt.

Other asteroids are piles of rubble held together by gravity. Most asteroids aren't quite massive enough to have achieved a spherical shape and instead are irregular, often resembling a lumpy potato. The asteroid 216 Kleopatra resembles a dog bone.

Asteroid orbits

Not all of the asteroids in our Solar System are found in the asteroid belt. Some asteroids pass near other planets, including Earth. Asteroids that come close to Earth are called Near Earth Objects. The planet Jupiter even shares its orbit around the Sun with two groups of asteroids, which are called Trojans.  If something slows an asteroid, it may "fall" towards the Sun, towards Mars, or towards Jupiter. As both Jupiter and Mars move past the asteroids in their orbits, they may be pulled slightly towards those huge bodies in their orbits. In fact, Phobos and Diemos, the two tiny moons of Mars, may be captured asteroids. Some scientists believe that the asteroid belt was made when a planet that was there exploded or collided with something else and broke up. Other scientists believe that the material making the asteroids never came together into a planet at all.

Craters

Craters are nicknamed “Snowman” because they look just like a snowman! They are on Vesta, one of the largest asteroids in the asteroid belt.

Many impact craters are found on the Earth’s surface, although they can be harder to detect. One of the best-known craters on Earth is Meteor Crater, near Winslow, Arizona. The crater was created instantly when a 50-meter (164-foot), 150,000-ton meteorite slammed into the desert about 50,000 years ago. Meteor Crater is 1.2 kilometers (0.75 miles) in diameter and 175 meters (575 feet) deep.

Impact craters are found on most of the solar system’s rocky planets and moons. The so-called “gas giants” of the solar system—Jupiter, Saturn, Uranus, and Neptune—don’t have craters. These planets are made up almost entirely of gases, so there is no hard surface for a meteor to impact. Meteors entering the atmosphere of a gas giant simply break up.



Cratering is a rare occurrence in the solar system today. Planets, moons, comets, and other celestial bodies have fairly stable orbits that do not interact with each other. Meteors do collide with planets—including Earth—every day. However, most of these meteors are the size of a speck of dust and do not cause any cratering. Most meteors burn up in the atmosphere as “shooting stars” before ever colliding with the surface of the Earth.

Ceres 

By far the largest object in the asteroid belt is Ceres. Made mostly of rock is Ceres. Made mostly of rock and ice, it was the first asteroid ever discovered. It has since been classed as a Dwarf Planet, because it is more like a planet than its neighbours in the main asteroid belt.

Ceres takes 1,682 Earth days, or 4.6 Earth years, to make one trip around the sun. As Ceres orbits the sun, it completes one rotation every 9 hours, making its day length one of the shortest in the solar system.

Ceres' axis of rotation is tilted just 4 degrees with respect to the plane of its orbit around the sun. That means it spins nearly perfectly upright and doesn't experience seasons like other more tilted planets do.

Ceres formed along with the rest of the solar system about 4.5 billion years ago when gravity pulled swirling gas and dust in to become a small dwarf planet. Scientists describe Ceres as an "embryonic planet," which means it started to form but didn't quite finish. Nearby Jupiter's strong gravity prevented it from becoming a fully formed planet. About 4 billion years ago, Ceres settled into its current location among the leftover pieces of planetary formation in the asteroid belt between Mars and Jupiter.

 

Picture Credit : Google

Scientists have always longed to explore Mars. They believe that in the past the Red Planet could have been far warmer and wetter than it is now. There may once have even been life on Mars, and tiny life forms, such as bacteria, could live on the planet today. Many spacecraft have already visited Mars and in the future humans will too.

Understanding whether life existed elsewhere in the Universe beyond Earth is a fundamental question of humankind. Mars is an excellent place to investigate this question because it is the most similar planet to Earth in the Solar System. Evidence suggests that Mars was once full of water, warmer and had a thicker atmosphere, offering a potentially habitable environment.

While life arose and evolved on Earth, Mars experienced serious climate change. Planetary geologists can study rocks, sediments and soils for clues to uncover the history of the surface. Scientists are interested in the history of water on Mars to understand how life could have survived. Volcanoes, craters from meteoroid impacts, signs of atmospheric or photochemical effects and geophysical processes all carry aspects of Mars’ history.

Samples of the atmosphere could reveal crucial details on its formation and evolution, and also why Mars has less atmosphere than Earth.

Water on Mars

In 2015, NASA found the strongest evidence yet that liquid water exists on Mars. This was a hugely exciting discovery because scientists looking for life in our Solar System think that where there is liquid water, there could be life.

Many lines of evidence indicate that water ice is abundant on Mars and it has played a significant role in the planet's geologic history. The present-day inventory of water on Mars can be estimated from spacecraft imagery, remote sensing techniques and surface investigations from landers and rovers. Geologic evidence of past water includes enormous outflow channels carved by floods, ancient river valley networks, deltas, and lakebeds; and the detection of rocks and minerals on the surface that could only have formed in liquid water. Numerous geomorphic features suggest the presence of ground ice (permafrost) and the movement of ice in glaciers, both in the recent past and present. Gullies and slope linear along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars, although to a far lesser degree than in the ancient past.

Curiosity Rover

The photo of the Curiosity rover was taken on the surface of mars. The six-wheeled, car-sized robot lives and works on the planet, operated by a team of scientists back on earth. Their instructions take about 15 minutes to reach Mars! Curiosity has other instruments on board that are designed to learn more about the environment surrounding it. Among those goals is to have a continuous record of weather and radiation observations to determine how suitable the site would be for an eventual human mission.

Curiosity's Radiation Assessment Detector runs for 15 minutes every hour to measure a swath of radiation on the ground and in the atmosphere. Scientists in particular are interested in measuring "secondary rays" or radiation that can generate lower-energy particles after it hits the gas molecules in the atmosphere. Gamma-rays or neutrons generated by this process can cause a risk to humans. Additionally, an ultraviolet sensor stuck on Curiosity's deck tracks radiation continuously.

Human exploration

To reduce the cost and risk for human exploration of Mars, robotic missions can scout ahead and help us to find potential resources and the risks of working on the planet.

Before sending astronauts, we need to understand the hazards. Inevitably, astronauts would bring uncontained martian material when they return to Earth, either on their equipment or on themselves. Understanding any biohazards in the soil and dust will help the planning and preparation of these future missions.

Going to Mars is hard and it is even harder for humans because we would need to pack everything to survive the trip to our neighbouring planet and back. Designing a Mars mission would be easier if we could use resources that are already available locally. Water is a valuable resource for human expeditions, both to consume by astronauts and for fuel. Samples gathered by robots could help to evaluate where potential resources are available for future human explorers and how to exploit them.

 

Picture Credit : Google

Like Earth, Mars has seasons. This is because the planets are tilted at similar angles. Different parts of the planet learn towards the Sun at different times during the year, making it warmer or cooler. Mars is an extremely cold planet with an average temperature around minus-80 degrees. Temperatures can dip to minus-225 degrees around the poles. Periods of warmth are brief — highs can reach 70 degrees for a brief time around Noon at the equator in the summer.

There’s no need to worry about rain on Mars — it hasn’t occurred for millions of years. With only trace amounts of water vapor, the planet is a dry and desolate place. Clouds do form, but they are very high in the sky and at the surface, where haze and fog forms as a result of the very steep lapse rates near the ground. Snow, on the other hand, is possible in the very high latitudes, though it’s nothing like the snow here on Earth.

With a very hot equator area and extremely cold poles, there are huge variations in temperature across the planet, which end up driving high wind speeds. Low pressure systems can form and polar fronts develop at the southern end of the polar ice cap, especially at times of seasonal changes.

Sometimes, these winds can lift very fine dust particles to create massive dust storms that envelop much of the planet. Heated dust particles can rise to over 20 miles above the surface. Wind velocities can reach 60 miles per hour or more in these storms.

 

Picture Credit : Google

Mars is nicknamed the Red Planet because of its rusty soil. Like Earth, it has a rocky surface, polar ice caps, mountains, valleys, and clouds in the sky. However, the fourth planet from the Sun has a far more extreme environment than ours. It is very cold and dry with a thin unbreathable atmosphere. Like Earth, Mars has seasons, polar ice caps, volcanoes, canyons, and weather. It has a very thin atmosphere made of carbon dioxide, nitrogen, and argon.

There are signs of ancient floods on Mars, but now water mostly exists in icy dirt and thin clouds. On some Martian hillsides, there is evidence of liquid salty water in the ground.

Scientists want to know if Mars may have had living things in the past. They also want to know if Mars could support life now or in the future

Mars’ moons

Mars has two moons, called Phobos and Deimos, which are much smaller than Earth’s Moon. Their names mean “panic” and “fear”. They were probably asteroids pulled towards Mars by its gravity.

 Phobos is a bit larger than Deimos, and orbits only 3,700 miles (6,000 kilometers) above the Martian surface. No known moon orbits closer to its planet. It whips around Mars three times a day, while the more distant Deimos takes 30 hours for each orbit. Phobos is gradually spiraling inward, drawing about six feet (1.8 meters) closer to the planet each century. Within 50 million years, it will either crash into Mars or break up and form a ring around the planet.

To someone standing on the Mars-facing side of Phobos, Mars would take up a large part of the sky. And people may one day do just that. Scientists have discussed the possibility of using one of the Martian moons as a base from which astronauts could observe the Red Planet and launch robots to its surface, while shielded by miles of rock from cosmic rays and solar radiation for nearly two-thirds of every orbit.

Like Earth's Moon, Phobos and Deimos always present the same face to their planet. Both are lumpy, heavily-cratered and covered in dust and loose rocks. They are among the darker objects in the solar system. The moons appear to be made of carbon-rich rock mixed with ice and may be captured asteroids.

Olympus Mons

Towering high above the Martian landscape is Olympus Mons. It is the largest volcano in our Solar System and nearly three times as high as Mount Everest!

Olympus Mons holds the title for tallest mountain in the solar system, and it is the second tallest mountain in the Universe. It likely became so large because Mars does not have tectonic plates. Therefore, the lava was likely able to flow outwards from a hotspot in the same place for quite a long time with no crust shifts to impede it.

The volcano is located in Mars's western hemisphere near the uplifted Tharsis bulge region. Since Mars is a small planet, and the slopes of Olympus Mons are so gradual, the edge of the volcano cannot be seen as it extends further than the horizon. Olympus Mons is so tall that it is often the only thing visibly protruding through Mars's massive dust storms.

Valles Marineris

 Valles Marineris is a 4,000 km (2500 mile) crack across the surface of Mars, at parts 7 km (4 miles) deep. It is a system of canyons, including the vast Coprates Chasma. Measuring the length of the entire United States, Mars’ Valles Marineris—Mariner Valley—is an enormous canyon that makes our Grand Canyon appear minuscule. Located along Mars’ equator, Valles Marineris spans one-fifth of the entire circumference of the planet. With depths of up to 4 miles and widths reaching up to 120 miles, the 2,500-mile-long canyon system is one of the largest in the entire Solar System. To put things into perspective, the Grand Canyon is a fraction of the size, running 277 miles long, up to 18 miles wide, and with a depth of only up to a little over a mile.

 

Picture Credit : Google

In outer space there is no air to breathe and the temperature can quickly change from being very hot to very cold. To survive astronauts must wear spacesuits. They are like an astronaut’s personal spacecraft, allowing them to do important jobs – such as repairing the space station.

Lots of layers

Spacesuits have 14 layers of material to help keep astronauts safe. The liquid cooling and ventilation garment makes up the first three layers. On top of this garment is the bladder layer. It creates the proper pressure for the body. It also holds in the oxygen for breathing. The next layer holds the bladder layer to the correct shape around the astronaut's body and is made of the same material as camping tents. The rip stop liner is the tear-resistant layer. The next seven layers are Mylar insulation and make the suit act like a thermos. The layers keep the temperature from changing inside. They also protect the spacewalker from being harmed by small, high-speed objects flying through space. The outer layer is made of a blend of three fabrics. One fabric is waterproof. Another is the material used to make bullet-proof vests. The third fabric is fire-resistant.

Life support system

The PLSS is worn like a backpack. It provides astronauts many of the things they need to survive on a spacewalk. Its tanks supply oxygen for the astronauts to breathe. It removes exhaled carbon dioxide. It contains a battery for electrical power.



The PLSS also holds water-cooling equipment, a fan to circulate oxygen and a two-way radio. A caution and warning system in this backpack lets spacewalkers know if something is wrong with the suit. The unit is covered with protective cloth layers. 

Spacesuit gloves have heaters in the fingertips to stop an astronaut’s fingers from getting cold! EVA gloves are made to protect astronauts from the space environment. They are also made so spacewalkers can move their fingers as easily as possible. The fingers are the part of the body that gets coldest in space. These gloves have heaters in the fingertips. A piece called a bearing connects the glove to the sleeve. The bearing allows the wrist to turn.

Astronauts see out of a clear plastic bubble, and also have a visor to protect them from the Sun’s harmful rays. The helmet keeps the oxygen at the right pressure around the head. The main part of the helmet is the clear plastic bubble.



The bubble is covered by the Extravehicular Visor Assembly. The visor is coated with a thin layer of gold that filters out the sun's harmful rays. The visor also protects the spacewalker from extreme temperatures and small objects that may hit the spacewalker.



A TV camera and lights can be attached to the helmet.

Display unit

This module is the control panel for the mini-spacecraft. Switches, controls, gauges and an electronic display are on the module. The astronaut can operate the Primary Life Support Subsystem from this module.

Astronauts can attach their boots to special foot restraints on the space station to make working in space easier.

Flying free

This space jetpack is called a “Manned Maneuvering Unit”. It was used by astronauts in the 1980s to travel in space without being tied to their spacecraft. Today, astronauts have smaller versions in case of emergencies. The MMU is a self-contained astronaut backpack propulsion device that allows astronauts to venture untethered from an orbiting spacecraft.  The unit is powered by 24 nitrogen gas thrusters, and its main structure is aluminum.  Other elements include two 16.8-volt silver zinc batteries, a control electronics assembly, and two hand controllers.

To use the MMU, an astronaut exits the Space Shuttle crew compartment through an airlock into the cargo bay.  There the astronaut dons the MMU and releases himself from the flight support station.  To maneuver in space, the astronaut uses the hand controllers.  The control electronics assembly translates the hand controller movements and fires the thrusters.  The astronaut can activate an auto-pilot system which will hold his attitude.

When not in use, the MMU is stowed and recharged in the flight support stations located in the forward end of the orbiter's payload bay.

 

Picture Credit : Google

The International Space Station (ISS) is the biggest object ever flown in space. It orbits at around 400 km (250 miles) above Earth and a team of astronauts have lived and worked here since the year 2000. It is our first step towards exploring deeper into the Solar System.

Astronauts do lots of scientific experiments on the space station to help us understand more about the effects of living in space. This will be useful knowledge for future deep-space exploration.

Keeping fit

There is no gravity in space, so astronauts exercise every day. It keeps them healthy and stops their muscles from getting weak. The heart and blood change in space. When we stand up on Earth, blood goes to our legs. The heart has to work extra hard against gravity to move the blood all around the body. In space, without the pull of gravity, the blood moves to the upper body and head. Water in the body also does the same thing. It makes the astronauts' faces look puffy. The blood and water are fluids in the body. These fluids move from the bottom of the body to the top. The brain thinks that there are too many fluids. It will tell the body to make less. When the astronauts come back to Earth, they do not have enough fluids in their systems. It takes their bodies a few days to make more blood and water. The astronauts have to rest so their bodies have time to make new blood and water. If they don't, they can feel very weak. They might even faint! 

Space walk

Sometimes astronauts have to go outside on spacewalks to repair the ISS. They wear special suits to protect them from the harsh environment of space. Inside spacesuits, astronauts have the oxygen they need to breathe. They have the water they need to drink.

Astronauts put on their spacesuits several hours before a spacewalk. The suits are pressurized. This means that the suits are filled with oxygen.

Once in their suits, astronauts breathe pure oxygen for a few hours. Breathing only oxygen gets rid of all the nitrogen in an astronaut's body. If they didn't get rid of the nitrogen, the astronauts might get gas bubbles in their body when they walked in space. These gas bubbles can cause astronauts to feel pain in their shoulders, elbows, wrists and knees. This pain is called getting "the bends" because it affects the places where the body bends. Scuba divers can also get "the bends."

Astronauts are now ready to get out of their spacecraft. They leave the spacecraft through a special door called an airlock. The airlock has two doors. When astronauts are inside the spacecraft, the airlock is airtight so no air can get out. When astronauts get ready to go on a spacewalk, they go through the first door and lock it tight behind them. They can then open the second door without any air getting out of the spacecraft. After a spacewalk, astronauts go back inside through the airlock.

Nice view

From the space station you can see entire countries, storms from above, and 16 sunsets and sunrises every day! Artificial structures visible from earth orbit without magnification include highways, dams, and cities. The Great Wall of China, often cited as the only human-made structure visible from space, is not visible from low Earth orbit without magnification, and even then can be seen only under perfect conditions. From US Space Shuttles, which typically orbited at around 135 mi (217 km), cities were easily distinguishable from surrounding countryside. Using binoculars, astronauts could even see roads, dams, harbours, even large vehicles such as ships and planes. At night, cities are also easily visible from the higher orbit of the ISS.

Metropolitan areas are clear at night, particularly in industrialized countries, due to a multitude of street lights and other light sources in urban areas

Robonaut

Robonaut 2 is a NASA (US space agency) robot astronaut that lives on the space station and helps the crew with sample tasks, such as changing air filters. Its head has cameras, which work like eyes, and its hands can operate simple tools.

One advantage of a humanoid design is that Robonaut can take over simple, repetitive, or especially dangerous tasks on places such as the International Space Station. Because R2 is approaching human dexterity, tasks such as changing out an air filter can be performed without modifications to the existing design.

Another way this might be beneficial is during a robotic precursor mission. R2 would bring one set of tools for the precursor mission, such as setup and geologic investigation. Not only does this improves efficiency in the types of tools, but also removes the need for specialized robotic connectors. Future missions could then supply a new set of tools and use the existing tools already on location.

 

Picture Credit : Google

In the middle of the 20th century the USA and the Soviet Union were struggling to be the most powerful country in the world. Both countries wanted to be the first to send spacecraft and people into space, and so the Space Race began.

The first man-made object to travel into space was the Soviet satellite Sputnik 1. It was launched on 4 October 1957.

A month later, on 3 November 1957, the Soviet Union sent a dog into space. She was called Laika, became the first living creature to orbit the Earth.

In April 1959, the US introduced its first group of astronauts, known as the Mercury 7. They were an elite group of pilots who did special training to travel to space.

But the Soviet Union sent a human to space first! On 12 April 1961, Russian cosmonaut Yuri Gagarin orbited the Earth.

In September 1962, US President John F. Kennedy set the goal of landing a man on the Moon by the end of the decade.

But the Soviets were still ahead, and in June 1963, Valentina Tereshkova became the first woman to travel to space.

In a further triumph, on 18 March 1965 the Soviet cosmonaut Alexei Leonov became the first person to walk in space!

However, the United States were first to the Moon. The Apollo 11 mission launched on 16 July 1969 and successfully landed on the Moon four days later.

On 20 July 1969, Neil Armstrong and Buzz Aldrin became the first people to walk on the Moon. The Space Race was over.

 

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Scientists think the Moon was formed when the Solar System was very young and an object about the size of Mars collided with the young Earth. They think the Moon is debris from the collision, pulled together in Earth’s orbit by gravity.

The giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact suggests that the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars, approximately 4.5 billion years ago, in the Hadean eon; about 20 to 100 million years after the Solar System coalesced. The colliding body is sometimes called Theia, from the name of the mythical Greek Titan who was the mother of Selene, the goddess of the Moon. Analysis of lunar rocks, published in a 2016 report, suggests that the impact may have been a direct hit, causing a thorough mixing of both parent bodies.

The giant-impact hypothesis is currently the favoured scientific hypothesis for the formation of the Moon. Supporting evidence includes:

• Earth's spin and the Moon's orbit have similar orientations.


• Moon samples indicate that the Moon's surface was once molten.


• The Moon has a relatively small iron core.


• The Moon has a lower density than Earth.


• There is evidence in other star systems of similar collisions, resulting in debris disks.


• Giant collisions are consistent with the leading theories of the formation of the Solar System.


• The stable-isotope ratios of lunar and terrestrial rock are identical, implying a common origin.

 

Picture Credit : Google

The Moon is our closet neighbour and the only place in the Solar System, other than Earth, that humans have set foot on. The Moon is desert-like, with plains, mountains and valleys, and a black sky. It is covered with craters, because there is no atmosphere to protect it from space rocks.

Like the Earth, the Moon has layers. The innermost layer is the lunar core. It only accounts for about 20% of the diameter of the Moon. Scientists think that the lunar core is made of metallic iron, with small amounts of sulfur and nickel. Astronomers know that the core of the Moon is probably at least partly molten.

Outside the core is the largest region of the Moon, called the mantle. The lunar mantle extends up to a distance of only 50 km below the surface of the Moon. Scientists believe that the mantle of the Moon is largely composed of the minerals olivine, orthopyroxene and clinopyroxene. It’s also believed to be more iron-rich than the Earth’s mantle.

The outermost layer of the Moon is called the crust, which extends down to a depth of 50 km. This is the layer of the Moon that scientists have gathered the most information about. The crust of the Moon is composed mostly of oxygen, silicon, magnesium, iron, calcium, and aluminum. There are also trace elements like titanium, uranium, thorium, potassium and hydrogen.

Moon landing

A total of twelve men have landed on the Moon. This was accomplished with two US pilot-astronauts flying a Lunar Module on each of six NASA missions across a 41-month period starting 20 July 1969 UTC, with Neil Armstrong and Buzz Aldrin on Apollo 11, and ending on 14 December 1972 UTC with Gene Cernan and Jack Schmitt on Apollo 17. Cernan was the last to step off the lunar surface.

All Apollo lunar missions had a third crew member who remained on board the Command Module. The last three missions included a drivable lunar rover, the Lunar Roving Vehicle, for increased mobility.

Moon exploration

The physical exploration of the Moon began when Luna 2, a space probe launched by the Soviet Union, made an impact on the surface of the Moon on September 14, 1959. Prior to that the only available means of exploration had been observation from Earth. The invention of the optical telescope brought about the first leap in the quality of lunar observations. Galileo Galilei is generally credited as the first person to use a telescope for astronomical purposes; having made his own telescope in 1609, the mountains and craters on the lunar surface were among his first observations using it.

NASA's Apollo program was the first, and to date only, mission to successfully land humans on the Moon, which it did six times. The first landing took place in 1969, when astronauts placed scientific instruments and returned lunar samples to Earth.

People last visited the Moon in 1972, but the footprints they left will last for millions of years because there is no wind to blow them away. This means future Moon explorers will be able to see them.

Solar eclipse

Sometimes when the Moon passes between the Earth and the Sun, the Moon briefly blocks out light from the Sun, causing an eclipse to be seen on Earth.

An eclipse is a natural phenomenon. However, in some ancient and modern cultures, solar eclipses were attributed to supernatural causes or regarded as bad omens. A total solar eclipse can be frightening to people who are unaware of its astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.

Since looking directly at the Sun can lead to permanent eye damage or blindness, special eye protection or indirect viewing techniques are used when viewing a solar eclipse. It is technically safe to view only the total phase of a total solar eclipse with the unaided eye and without protection; however, this is a dangerous practice, as most people are not trained to recognize the phases of an eclipse, which can span over two hours while the total phase can only last a maximum of 7.5 minutes for any one location. People referred to as eclipse chasers or umbraphiles will travel to remote locations to observe or witness predicted central solar eclipses.

Mining the Moon

In the future there could be a Moon base, where people could live. Some scientists are even interested in mining the Moon for resource they could turn into rocket fuel.

If human beings are to explore the Moon and, potentially, live there one day, we’ll need to learn how to deal with these challenging environmental conditions. We’ll need habitats, air, food and energy, as well as fuel to power rockets back to Earth and possibly other destinations. That means we’ll need resources to meet these requirements. We can either bring them with us from Earth – an expensive proposition – or we’ll need to take advantage of resources on the Moon itself. And that’s where the idea of “in-situ resource utilization,” or ISRU, comes in.

Underpinning efforts to use lunar materials is the desire to establish either temporary or even permanent human settlements on the Moon – and there are numerous benefits to doing so. For example, lunar bases or colonies could provide invaluable training and preparation for missions to farther flung destinations, including Mars. Developing and utilizing lunar resources will likely lead to a vast number of innovative and exotic technologies that could be useful on Earth, as has been the case with the International Space Station.

 

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From the biggest whale in the ocean to a tiny mouse, all life on Earth has one thing in common – it is all made from the same stuff.

Stardust

Nearly everything that makes up our bodies, and everything else on Earth, was created when dying stars exploded. These explosions send raw materials like carbon and oxygen hurtling across space, and these raw materials are what we are made of. That means that you are made of stardust! When the universe started, there was just hydrogen and a little helium and very little of anything else. Helium is not in our bodies. Hydrogen is, but that's not the bulk of our weight. Stars are like nuclear reactors. They take a fuel and convert it to something else. Hydrogen is formed into helium, and helium is built into carbon, nitrogen and oxygen, iron and sulfur—everything we're made of. When stars get to the end of their lives, they swell up and fall together again, throwing off their outer layers. If a star is heavy enough, it will explode in a supernova.

So most of the material that we're made of comes out of dying stars, or stars that died in explosions. And those stellar explosions continue. We have stuff in us as old as the universe, and then some stuff that landed here maybe only a hundred years ago. And all of that mixes in our bodies.

 

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Although there may be life elsewhere in our Solar System, we haven’t discovered it yet. The only place we know has life for sure is Earth. Our home planet is at just the right distance from our Sun for liquid water to exist, and has all the other key ingredients to make life possible.

Life is a characteristic that distinguishes physical entities that have biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have ceased (they have died), or because they never had such functions and are classified as inanimate. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, or potential synthetic life as "living". Biology is the science concerned with the study of life.

There is currently no consensus regarding the definition of life. One popular definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve. However, several other definitions have been proposed, and there are some borderline cases of life, such as viruses or viroids.

Recipe for life

In the mixing bowl are the key ingredients needed for life as we know it:

You will need:

Raw materials, such as oxygen, nitrogen, and carbon

Liquid water

Energy

Raw material

The raw materials needed for life are found all over Earth – for example in soil. However soil needs water and energy from the Sun before life can appear. Life as we know it contains specific combinations of elements including carbon, hydrogen, nitrogen, and oxygen that combine to form proteins and nucleic acids which can replicate genetic code. All the basic elements are formed in stars and distributed throughout space as a result of giant explosions called supernovas. Since these essential chemicals are quite common in other places in the Universe we can expect that the development of life somewhere else is also possible.

Water

Liquid water is essential for life. It allows crucial changes to take place between raw materials. Liquid water is essential because biochemical reactions take place in water. Water is also an excellent solvent that easily dissolves and carries nutrients and other compounds in and out of cells. Life forms are usually made primarily of water. In fact, our human bodies are more than 60% water.

Energy

Life on Earth would not be possible without a constant source of energy, such as the Sun. Organisms require energy to assimilate or put together the chemicals that form an individual. Energy is also required for the organism to grow, reproduce, and respond to the environment. Energy sources may include other organisms, light, or inorganic compounds. The most common source of energy on the Earth is photosynthesis, which transforms sunlight into food. This process will not work very well for the outer Solar System, because not much light reaches such great distances. However, we can look to extremophiles here on Earth for help in figuring out where and what to search for. Extremophiles live in extreme conditions and typically get their energy from a source other than the sun.

 

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Earth and Venus are about the same size, and are made up of similar rocky materials. They are also neighboring planets. However, Venus and Earth are also very different. Venus has an atmosphere that is about 100 times thicker than Earth's and has surface temperatures that are extremely hot. Venus does not have life or a water ocean like Earth does. Venus also rotates backwards compared to Earth and the other planets.

But that’s where the similarities end! Venus is a deadly world. It‘s boiling hot, covered in volcanoes, and cloaked in an atmosphere of deadly poisonous gases

Volcanoes: Venus is covered in volcanoes. There is evidence that some may still be erupting. On Earth, volcanoes are mainly of two types: shield volcanoes and composite or stratovolcanoes. The shield volcanoes, for example those in Hawaii, eject magma from the depths of the Earth in zones called hot spots. The lava from these volcanoes is relatively fluid and permits the escape of gases. Composite volcanoes, such as Mount Saint Helens and Mount Pinatubo, are associated with tectonic plates. In this type of volcano, the oceanic crust of one plate is sliding underneath the other in a subduction zone, together with an inflow of seawater, producing gummier lava that restricts the exit of the gases, and for that reason, composite volcanoes tend to erupt more violently.

Barren surface: There are no rivers or lakes on the surface of Venus. The only rain it gets is acid rain that would burn trough your skin.

Toxic clouds: Venus is covered in clouds of sulphuric acid. The atmosphere is so thick it would crush you in seconds.

Atmosphere: Earth’s atmosphere protects it from dangerous space radiation, and contains gases like oxygen that we need to breathe. Venus’s atmospheric pressure is greater than that of any other planet – more than 90 times that of Earth’s. This pressure is equivalent to being almost one kilometre below the surface of Earth’s oceans. The atmosphere is also very dense and mostly carbon dioxide, with tiny amounts of water vapour and nitrogen. It has lots of sulphur dioxide on the surface. This creates a Greenhouse Effect and makes Venus the hottest planet in the solar system. Its surface temperature is 461 degrees Celsius across the entire planet, while Mercury (the closest planet to the Sun) heats up to 426 Celsius only on the side facing the Sun.

Life: Earth is home to an amazing variety of plants and animals.

Water: About 71 per cent of Earth’s surface is covered by water. It is a vital ingredient for life.

Temperature: The surface temperature on the planet Earth goes only to about 100 degrees Fahrenheit, which makes it possible for life to thrive on this planet. On the other hand, the surface temperature on the planet Venus is nine times hotter than that on planet Earth. As such, it is extremely impossible for any form of life to survive and thrive on Venus’ surface.

 

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Mercury has a rocky surface, but inside is a very large metallic core, part of which is molten (liquid).

Crust: Mercury has a thick crust that is composed mostly of silicate rocks. Mercury may have small ice caps at its north and south poles; this ice stays frozen inside deep craters that are shaded from sunlight. 



Mantle: Beneath the crust it is a mantle (also made of silicate rocks) that is hundreds of kilometers thick. 



Core: At the center of Mercury is a partly-molten iron core about 2,300 miles (7,500 km) in diameter (almost half of the diameter of Mercury). This core accounts for about 80% of Mercury's mass. This core generates a magnetic field (which is how we know that Mercury has an iron core). 



Density: Mercury has a density of 5,430 kg/m3, slightly less than that of Earth. Mercury is the second-densest planet in the solar system (after Earth) because of its large iron core. 

People have been observing Mercury for a very long time, but nobody knows who discovered it. Sometimes it can be seen from Earth around sunset and sunrise. Sunrise and sunset on Mercury are spectacles to behold. Two and one half times larger in the sky than seen on Earth, the sun appears to rise and set twice during a Mercurian day. It rises, then arcs across the sky, stops, moves back toward the rising horizon, stops again, and finally restarts its journey toward the setting horizon. These aerial maneuvers occur because Mercury rotates three times for every two orbits around the sun and because Mercury's orbit is very elliptical.

Visible at night: Mercury is not the only planet that can be seen with the naked eye. Mercury can generally be observed with a naked eye as it has the sun as a bright backdrop. Mercury is best observed with the naked eye during times right before and after the sun has set, which gives enough light pollution to contrast the shadow of Mercury. A general time to try and view Mercury with your naked eye is 90 minutes before sunrise or after sunset.

 

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 Mercury is the closest planet to the Sun and the least explored of the four inner rocky planets. Its surface is covered in greyish-brown dust and looks similar to our Moon, with lots of craters where it has been hit by space rocks. Scientists think there is no possibility of life here.

Mercury is smallest of the eight planets in our Solar System – it is only slightly bigger than the Earth’s Moon.

Mercury is a world of extreme temperatures. By day it is scorching hot, but at night it is very cold.

Mercury is not the hottest planet in the solar system. With no atmosphere to trap heat, surface temperatures on Mercury can swing from 800 degrees Fahrenheit during the day to -290 degrees Fahrenheit at night. Mercury may even have reservoirs of ice sitting deep inside permanently shadowed craters at its poles. By contrast, the surface of hazy Venus sits at a sweltering 880 degrees Fahrenheit year-round, making it the hottest planet in our solar system.

Lack of an atmosphere also means Mercury’s surface is pockmarked by numerous impact craters, since incoming meteors don’t encounter any friction that would cause them to burn up. Seen via telescopes and spacecraft, Mercury looks like a battered world covered in overlapping basins, soaring cliffs, and occasional smooth plains.

Bright lines called crater rays also crisscross the surface where impacts crushed the rock and kicked up reflective debris. One of the most notable features on Mercury is Caloris Basin, an impact crater about 960 miles wide that formed early in the planet’s history. Mercury has no rings, no moons, and a relatively weak magnetic field.

 

Picture Credit : Google