My Science School

A crater is formed when a small space body such as an asteroid or a meteor collides with the surface of a planet or a moon. The Earth and the Moon both have many craters but the chances of Earth being hit by a space body is far more than the Moon due to its large size. However, despite its size, the moon has thousands of craters while we know of only 180 on Earth. Why?

Both Earth and Moon have been hit many, many times by small space bodies throughout their existence. However, the Earth has processes that can erase almost all evidence of a crater, unlike the Moon. The three processes are:

Erosion

The Earth has water (rain, floods), plants (break up earthen materials) and weather (wind, etc.) which can act together and erode over a period of time erosion can break a crater down to almost nothing.

The Moon on the other hand has no erosion because it has no atmosphere. This means it has no wind, no water and definitely no plants that can erode its surface and remove marks off its surface.

Tectonics

Tectonics are processes that cause Earth’s surface to form new rocks and get rid of old ones due to their shifting around over millions of years. Because of this, Earth’s surface is recycled many times throughout its existence, leaving it with very few rocks that are as old as those on the Moon. Since the Moon has not had tectonics for billions of years, it has a lot of time to stay put.

Volcanism

Volcanic flows on Earth can cover up impact craters. This is also the way may impact craters get covered in other parts of the solar system. While the Moon had large volcanic flows in the past that covered up most of its craters, it hasn’t had volcanism in nearly three billion years!

 

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Apart from planets, stars and moons, there are several small solar system bodies such as asteroids and comets in space. These are usually speeding through space. Sometimes, a larger body such as a planet or a moon can come in their way. When this happens, these extremely fast spacebodies crash into the surface of the larger space body and create a depression called impact crater.

For an object to be able to create an impact crater, it needs to be travelling at a speed of many thousand kilometres per hour. No matter how hard or tough the surface of a planet or the moon is, when a superfast object collides with it, it will definitely leave an impact by vaporizing the area and creating enormous shockwaves through the ground, which can melt and recrystallise rock.

The size and shape of a crater depends on factors such as mass, density and velocity of the impacting object, and the geology and velocity of the impacting object, and the geology of the surface it strikes. Many planets and moons in our solar system have impact craters.

Two of the famous impact craters on Earth are:

Meteor Crater

Also known as the Barringer Crater in Arizona, the U.S., this is the first crater formed by an extraterrestrial impact to be identified. It formed nearly 50,000 years ago from a meteorite that may have been up to about 150 feet wide travelling at more than 45,000 kmph.

Vredefort crater

Situated in South Africa, this is the largest-known impact crater on Earth. It is nearly 300 km in diameter and over two billion years old. However, due to erosion over time, it is difficult to see the crater. What remains today are geological structures at its centre known as the Vredefort Dome or Vredefort impact structure.

 

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Our Sun is one of many stars in our galaxy and our galaxy, the Milky Way, is one of many galaxies in the Universe. It is not yet possible for humans to travel beyond our Solar System, but by using telescopes scientists are able to take pictures of galaxies trillions and trillions of kilometers away.

Looking into deep space

Using space telescopes, scientists have seen stars being born and dying, and observed very distant galaxies. They have been able to work out that the Universe is nearly 14 billion years old.

Hubble Telescope

Orbiting above the Earth is the Hubble Space Telescope. The size of a large school bus, it faces out towards space and takes pictures of distant stars and galaxies.

Exoplanets

Our Sun is not the only star that has planets orbiting around it. Lots of other stars have planets, too, and scientists call these “exoplanets”.

Kepler-22b

This Earth-like planet was found orbiting around a star nearly 600 light years away from Earth. A light year is the distance light can travel in a year.

 

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Voyager 1 and 2 are twin spacecrafts that were launched in the 1970s. Since then they have been on an incredible journey across the Solar System, visiting the planets Jupiter, Saturn, Uranus, and Neptune. The mission was far more successful than scientists had imagined it would be, and the spacecrafts are still sending back information to earth.

Jupiter

Voyager 1 and 2 took pictures of Jupiter’s Great Red Spot and saw that one of its moons, called Io, has active volcanoes.

Saturn

Both spacecrafts photographed Saturn’s rings and moons. Scientists learned about what Saturn was made of and what its weather was like.

Uranus

Voyager 2 was the first spacecraft to visit Uranus. It discovered ten new moons around the planet!

Neptune

In the late 1980s Voyager 2 reached Neptune, the final planet on its tour. It passed close to Neptune’s largest moon, called Triton.

Leaving the Solar System

On 25 August 2012, Voyager 1 became the first human-made object to leave the Solar System!

Pioneer missions

Launched just before the Voyager missions, Pioneer 10 and 11 were the first spacecrafts to cross the asteroid belt and visit Jupiter and Saturn.

Family portrait

The Pioneer project also sent probes to visit the inner planets and to orbit the Earth, some of which launched in the 1950s.

Anyone out there?

In case they are found by aliens, the Pioneer probes carry plaques showing the position of Earth in the Solar System and what humans look like!

 

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Dr Piers is a British-American NASA astronaut and climate scientist. In his space career he made three Space Shuttle flights. He completed six spacewalks, during which he helped to build the International Space Station!

Space is the new frontier. It is to us what the oceans were to sailors a thousand years ago. We have to cross space to get the planets in our Solar System. One day. We will travel to planets around other stars. We hope future space explorers will travel to Mars, then the moons of the outer planets.

Zero-G is great fun. You can float through the air down the big main corridor of the space station. It’s like magic. But the view of Earth is the main thing. From the ISS you can see over 1,000 miles in all directions – beautiful.”

It’s hard to sleep in space. When you close your eyes you feel like you are falling and so you wake up! You can’t shower in zero-G – the water would go everywhere. So you wipe yourself down with a wet washcloth, which works ok. The loo works using an air suction fan to make everything go where it’s supposed to go, and that works fine, too!

The best part of being an astronaut is spacewalking. Being outside the spacecraft you have a beautiful all-round view of the Earth and space.

How do you become an astronaut?

Currently, you have to be one of the following to be a professional astronaut: military test pilot, engineer, medical doctor, or scientist. So study hard on the STEM subjects [science, technology, engineering, and mathematics] at school. They are hard to begin with, but fascinating and worthwhile.

 

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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.

Helmet

Astronauts see out of a clear plastic bubble, and also have a visor to protect them from the Sun’s harmful rays.

Lots of layers

Spacesuits have 14 layers of material to help keep astronauts safe. Some of these layers protect them from dangerous objects that fly through space.

Life support system

Worn like a backpack, the life support system contains oxygen for the astronaut to breathe, and a battery for electrical power.

Display unit

Astronauts operate their life support system using controls on their display unit.

Gloves

Spacesuit gloves have heaters in he fingertips to stop an astronaut’s fingers from getting cold!

Boots

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

Flying free

Manned Maneuvering Unit 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.

 

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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.

Experiments

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.

Canadam2 is a robotic arm that moves equipment around the ISS. Science experiments are carried out in the Columbus laboratory. The Japanese Kibo laboratory has a mini airlock, so astronauts can put experiments outside. Oxygen is generated in the Tranquility module. The Soyuz capsule carries people and supplies to and from the ISS.

Keeping fit

There is no gravity in space, so astronauts exercise every day. It keeps them healthy and stops their muscles from getting weak.

Spacewalk

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.

Nice view

From the space station you can see entire countries, storms from above, and 16 sunsets and sunrises every day!

Robonaut

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

 

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

Moon landings

Twelve people have walked on the Moon, the first being Neil Armstrong. People have driven cars on the Moon, called Lunar Rovers, and even played golf!

Moon Exploration

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.

Earthrise

Apollo 8 was the first manned mission to orbit the Moon. The photograph was taken on Christmas Eve 1968.

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.

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 resources they could turn into rocket fuel.

How the Moon formed?

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.

 

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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.

Recipe for life

 In the mixing bowl are the key ingredients needed for life as we know it. You will need:

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.

Water

Liquid water is essential for life. It allows crucial changes to take place between raw materials.

Energy

Life on Earth would not be possible without a constant source of energy, such as the Sun.

What are we made of?

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. It may not look like a whale, but a mouse is made of the same raw materials.

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!

 

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Earth and Venus are about the same size, and are made up of similar rocky materials, 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.

Venus:

Volcanoes

Venus is covered in volcanoes. There is evidence that some may still be erupting.

Barren surface

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

Toxic clouds

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

Earth:

Atmosphere

Earth’s atmosphere protects it from dangerous space radiation, and contains gases like oxygen that we need to breathe.

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

With its distance from the Sun, Earth is the perfect temperature for life – neither too hot nor too cold.

 

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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 grayish-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.

Smallest planet

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

Extreme temperatures

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

What’s inside?

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

Planet-gazing

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.

Visible at night

Mercury is not the only planet that can be seen with the naked eye. The others are Venus, Mars, Jupiter and Saturn.

 

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Located at the centre of the Solar System is the Sun. it is a star, like the ones you see in the night sky. A burning ball of gas, made of mostly hydrogen and helium, it provides us with the heat we need to survive. The Sun is so massive that its gravity – the force that pulls things together – keeps the planets in orbit around it.

Our Star

Energy is constantly being generated deep within the Sun. it can take up to 100,000 years for energy to reach the surface, but then it only takes 8 minutes to reach the Earth!

Solar flare

Huge eruptions from the surface of the Sun are called solar prominences. They form loops because of the Sun’s invisible magnetic field.

Sunspot

Dark patches that appear on the surface of the Sun are called sunspots. They are cooler areas that usually last for a few weeks.

How big is the Sun?

The Sun is so ginormous that all of the planets of the Solar System could fit inside it hundreds of times over.

Auroras

As well as heat and light, the Sun blasts out special particles called solar wind. When these get trapped by Earth’s magnetic field near the poles they can create spectacular light shows, called auroras.

 

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The Solar System is located in the Milky Way, a huge spiral galaxy containing billions of stars. They are grouped in “arms” that spiral outwards. All of the stars are travelling around a point at the centre. Scientists think there is a supermassive black hole located there that sucks in anything that gets too close to it.

The night sky

On a clear, dark night it is possible to see the Milky Way stretching across the sky at night, cloudy band. Although the Milky Way is a spiral galaxy, it doesn’t look like it from Earth because we are inside it!

Black hole

The pull of gravity from a black hole is so great that not even light can escape it. Supermassive black holes, like the one at the centre of the Milky Way, also fire out jets of energy.

 

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The Solar System is made up of our star, called the Sun, and everything that travels, or orbits, around it. This includes eight planets and their moons, dwarf planets, asteroids, comets, and smaller bits of rock and dust. The Solar System is one of many solar systems that exist in the Universe.

Asteroids

Asteroids are lumps of rock and metal left over from when the Solar System first formed. Most can be found in the asteroid belt, which is located between the planets Mars and Jupiter.

Gas planets

The four outer planets – Jupiter, Saturn, Uranus and Neptune – are the largest planets in the Solar System. They are mostly made of gas and spacecraft are unable to land on them.

Rocky planets

Closest to the Sun are the four rocky planets – Mercury, Venus, Earth, and Mars. They all began their existence in the same way, but over time became very different worlds.

Dwarf planets

Dwarf planets, such as Pluto, also travel around the Sun. These worlds are smaller than the other planets. Scientists think there may be dozens of undiscovered dwarf planets hiding in the Solar System.

Super-sized

The Solar System is so big that if the Sun were the size of a basketball, the Earth would be the size of a sesame seed – and it would be located more than 25 m (80 ft) away!

 

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