My Science School

The Sun won’t last forever. Just like other stars in the Universe, the Sun was born and it will die. At 4.6 billion years old, the Sun is almost halfway through its life. In about 5 billion years time it will start to change, as it burns up the fuel that kept it shining bright for so long. It will expand to become a type of star called a red giant, before shrinking to become a white dwarf.

Life of the Sun

The Sun is a medium-sized star. The Sun was born in a nebula – a giant cloud of gas and dust. The Sun is currently middle-aged. It is about halfway through its life. As it runs out of fuel, the Sun starts to collapse, but this causes it to heat up again. The outer layers of the Sun expand to turn it into a red giant. The Sun throws off its outer layer of gas and dust. The Sun will spend its final days as a white dwarf, a star about the same size as Earth.

Eating Mercury

The red giant Sun will become so enormous that it will gobble up the planet Mercury!

 

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It is one of the great unanswered questions. Some scientists think it is very likely that the Universe is full of life. Their motto is “follow the water”, as they believe the best place to find life will be where there is liquid water. Within our own Solar System there are several places of interest to these scientists.

Candidates for life

Although finding intelligent life, like us, in our own Solar System is unlikely, there are words that may be home to simple forms of life. Scientists are interested in these places because they have conditions that might be suitable for life to exist.

Europa

Scientists believe that there is a liquid water ocean under the thick frozen surface of Jupiter’s moon, Europa. Life has been found at the deepest, darkest parts of Earth’s oceans, and scientists think the same thing might be possible on Europa.

Mars

Mars is of interest to scientists because of the recent discovery of flowing water on its surface. It is possible that life may have existed on the planet in the past, or that some form of life may still exist today.

Enceladus

Enceladus is a moon that orbits around Saturn. It has a frozen surface and scientists think there is liquid water underneath. The Cassini spacecraft has been flying through geysers of frozen water that erupt from the surface, and analyzing it to see if it could harbor life.

Titan

Titan is Saturn’s largest moon. It has a thick atmosphere and seas made of liquid gas. Titan is very interesting may be similar to that of the early Earth – before life emerged on our planet.

SETI Institute

SETI stands for “Search for Extra Terrestrial Intelligence”. The SETI Institute, based in California, USA, is looking for evidence of life in the Solar System and the wider Universe. SETI scientists try to find places that may have the ingredients needed for life and also listen out for possible signals that may have come from aliens. SETI believe our first contact with intelligent life in the Universe may even be with robots built by alien civilizations!

 

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Did you know that you are a different age on each planet? This is because a year is the time it takes an object in the Solar System to orbit the Sun. every planet or dwarf planet takes a different length of time to do this, so their years can be long or short. A year on Earth is the same as about four years on Mercury, while a year on Pluto takes 248 Earth years!

Mercury

Mercury flies round the Sun more quickly that the other planets – its year is only 88 Earth days long. That means that if you are 10 on Earth, you are 41 on Mercury!

Venus

A day is the amount of time it takes a planet to spin once. Venus takes 225 Earth days to orbit the Sun, but it spins very slowly. This means the days on Venus are very long. In fact, a day on Venus is longer than a year on Venus!

Pluto

Pluto is so far from the Sun that you would wait a long time for your first birthday. It would take 2,480 Earth years to turn 10!

Neptune

A year on Neptune takes 165 Earth years. This means that it is impossible to turn one on Neptune in a human lifetime.

 

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The spacecraft Rosetta and its lander Philae travelled for ten years across the Solar System to reach the comet 67P/Churtyumov-Gerasimenko. To get enough speed, the spacecraft had to loop around the Earth three times and Mars once, using the gravity of the planets to slingshot through space. On the way they passed lots of other fascinating objects. Finally, in 2014, Philae made the first ever successful touchdown on a comet.

Rosetta was set to be launched on 12 January 2003 to rendezvous with the comet 46P/Wirtanen in 2011. This plan was abandoned after the failure of an Ariane 5 ECA carrier rocket during Hot Bird 7's launch on 11 December 2002, grounding it until the cause of the failure could be determined. In May 2003, a new plan was formed to target the comet 67P/Churyumov–Gerasimenko, with a revised launch date of 26 February 2004 and comet rendezvous in 2014. The larger mass and the resulting increased impact velocity made modification of the landing gear necessary.

After two scrubbed launch attempts, Rosetta was launched on 2 March 2004 at 07:17 UTC from the Guiana Space Centre in French Guiana, using Ariane 5 G+ carrier rocket. Aside from the changes made to launch time and target, the mission profile remained almost identical. Both co-discoverers of the comet, Klim Churyumov and Svetlana Gerasimenko, were present at the spaceport during the launch

Giant comet

The comet that Rosetta and Philae visited is 4.1 km (2.5 miles) long. That’s roughly the same height as 10 Empire State Buildings stacked up!

 

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Our Solar System isn’t just made up of planets, dwarf planets, and moons. There are lots of other objects that make up the Solar System family. Comets and asteroids have existed since the Solar System formed, and both have hit Earth in the past. There are also smaller bits of rock and dust, called meteoroids, meteors and meteorites.

Asteroid

An asteroid is a rocky object that orbits the Sun. they are much smaller than planets. Some are less than 1 km (0.6 miles) wide.

Meteoroid

A small piece of rock or space dust that has broken off an asteroid or comet is called a meteoroid.

Meteor

A meteoroid that burns up as it passes through the Earth’s atmosphere is called a meteor. They are also known as “shooting stars”.

Meteorite

If the meteor makes it to the ground it is called a meteorite.

Comets

Made from rock, ice and dust, comets are the size of mountains. There are thousands of billions of comets in our Solar System.

Orbiting the Sun

Comets travel around the Sun in an oval-shaped orbit. Some comets are so far away they take tens of millions of years to orbit the Sun. comets get tails when they pass near the Sun and are heated up. The tails always point away from the Sun.

Death of the dinosaurs

 Every day around 90 tonnes (100 tons) of rock and dust from space smashes into the Earth. Most of it burns up in the atmosphere, but larger objects can reach the ground. Scientists think a meteorite about 10 km (6 miles) wide hit into the Earth about 65 million years ago, wiping out the dinosaurs.

 

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Pluto was once thought to be a barren, boring lump of rock at the edge of the Solar System. However, a recent mission has shed new light on this mysterious world. It is filled with ice mountains and volcanoes, and it has particles in its atmosphere that scatter sunlight, giving it a blue sky just like on Earth.

Strange surface

In 2015, photos revealed Pluto’s surface for the first time. NASA scientists spotted smooth plains riddled with craters and mountains of ice.

Dwarf planets

In 2006, it was decided Pluto wasn’t a planet, but a dwarf planet. Dwarf planets are similar to planets in many ways, but share their orbits around the Sun with other objects, such as asteroids and comets. There are currently five recognized dwarf planets in the Solar System, but it thought there are many more.

New Horizons

In 2015 the New Horizons probe made a close flyby of Pluto. It was the first time the dwarf planet had been seen in such clear detail, revealing a world far more active than was previously thought.

Charon

When it wasn’t busy snapping shots of Pluto, New Horizons had the chance to photograph Pluto’s biggest moon, Charon.

The Kuiper Belt

The Kuiper Belt is made up of millions of icy and rocky objects that orbit the Sun at the edge of the Solar System. It is also home to dwarf planets. New Horizons will do its first flyby of a Kuiper Belt object in 2019.

 

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Cold and dark, Uranus and Neptune are known as ice giants because they are made of a mix of gas and icy materials. Both worlds have small rings and many moons. They have only been visited by one spacecraft, Voyager 2, and are still waiting to be explored.

Spinning on its side

Uranus is the odd-ball of the Solar Systems, as it orbits the Sun tilted on its side! Scientists think this is because Uranus was struck by an Earth-sized object early in its life, knocking it over.

Stormy planet

Neptune is the wildest planet in the Solar System. Winds tear through Neptune’s clouds at speeds of up to 2,000 kph (1,200 mph). These ferocious winds once blew a huge storm across the planet. It was called the Great Dark Spot and it was the size of the Earth!

Great Dark Spot

This storm was spotted by Voyager 2 when it visited Neptune in 1989. It had disappeared by the next time Neptune was viewed.

 

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Saturn is the second largest planet, after Jupiter, and is known as the “Jewel of the Solar System” because of its spectacular rings. It is a gas giant that spins so fast it bulges out in the middle.

Bathtime

Despite its mammoth size, Saturn isn’t very dense. This means that if you could build a gigantic bath, Saturn would float in it!

Lord of rings

Saturn is surrounded by rings that are made up of billions of chunks of rock and ice. The rings can be seen from Earth through a telescope.

Saturn has 53 known moons with an additional 29 moons awaiting confirmation of their discovery—that is a total of 82 moons. Saturn cannot support life as we know it, but some of Saturn's moons have conditions that might support life. About two tons of Saturn’s mass came from Earth—the Cassini spacecraft was intentionally vaporized in Saturn’s atmosphere in 2017.

 

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Jupiter’s four largest moons were the first moons to be discovered orbiting another planet. They are incredible worlds of volcanoes, craters and hidden oceans that have barely been explored. Some could be home to alien life!

Io

Io is similar in size to the Earth’s moon. Chemicals from volcanic eruptions have turned its surface yellow-orange. Io is the most volcanically active world in our Solar System. Hundreds of volcanoes spew lava thousands of metres into the air.

Europa

Europa is the smallest of Jupiter’s four largest moons. On the surface there is water ice and underneath scientists believe there is an ocean! Gigantic jets of water are thought to spout from geysers on Europa’s icy surface. These fountains may be up to 20 times higher than Mount Everest!

Ganymede

The largest moon in our Solar System, Ganymede is even bigger than the planet Mercury! It is made of rock and ice.

Callisto

This battered moon has more craters than any other object in the whole Solar System!

In the night sky

If you look at Jupiter through a telescope you might see bright lights hovering next to the planet. These are actually its four largest moons!

Jupiter’s four largest moons are known as the Galilean moons, after the Italian scientist Galileo Galilei, who discovered them in 1610.

In orbit

With at least 67 moons, Jupiter is almost like its own mini Solar System. Io is the closest of the four largest moons and takes 42 hours to orbit around the planet. Callisto, the furthest away, takes around seventeen days to complete its orbit.

 

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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!

Giant planet

Jupiter is the king of the Solar System. It is an amazing 143,000 km (89,000 miles) wide. Jupiter is so large that all of the other planets could fir inside it!

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.

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.

Beneath the clouds

Any spacecraft 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.

Great Red Spot

One of 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!

 

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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!

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.

Craters

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

Ceres

By far the largest object in the asteroid belt 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.

 

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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.

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.

Curiosity Rover

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 17 cameras on board. As well as taking photos, this camera can fire a laser to clean away dust from Martian rocks!

Curiosity’s robotic arm holds tools for examining the surface. Wide, grippy wheels help the rover travel over bumpy terrain.

 Human exploration

One day people will walk on Mars. Astronauts will see the landscape with their own eyes and become the first humans to walk on another planet. Even if no life is found, reaching Mars will be a crucial step on the way to exploring the wider Solar System.

 

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Like Earth, Mars has seasons. This is because the planets titled at similar angles. Different parts of the planet lean towards the Sun at different times during the year, making it warmer or cooler.

Mars is titled just 1.5  more than Earth, so it has a similar range of seasons. Seasons on Mars last longer because it takes longer for Mars to travel around the Sun.

On Mars there are huge dust storms that last for weeks. So mush dust is kicked up that they can be seen by telescopes on Earth!

Due to the extreme lows in temperature at the poles, 25-30% of the carbon dioxide in the atmosphere freezes and becomes dry ice that is deposited on the surface. While the polar ice caps are predominantly water, the Martian North Pole has a layer of dry ice measuring one meter thick in winter, while the South Pole is covered by a permanent layer that is eight meters deep.

 

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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.

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. Given their composition, size and shape, astronomers think that both of Mars’ moons were once asteroids that were captured in the distant past.

Compared to our Moon, Phobos and Deimos are rough and asteroid-like in appearance, and also much smaller. In addition, their composition (as already noted) is similar to that of C-type asteroids that are common to the Asteroid Belt. Hence, the prevailing theory as to their origin is that they were once asteroids that were kicked out of the Main Belt by Jupiter’s gravity, and were then acquired by Mars.

 

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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.

Mars is approximately half the diameter of Earth, with a surface area only slightly less than the total area of Earth's dry land. Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. The red-orange appearance of the Martian surface is caused by iron(III) oxide, or rust. It can look like butterscotch; other common surface colors include golden, brown, tan, and greenish, depending on the minerals present.

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 is part of a complex of volcanoes that lie along a volcanic plateau called the Tharsis Bulge. This entire region lies over a hotspot, a place in the planet’s crust that allows magma from deep inside to flow out to the surface. While planetary scientists have not recorded a volcanic eruption on Mars in real time, there is evidence of geologically recent flows perhaps in the past few tens of millions of years. It is possible that Mars is not yet volcanically dead.

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. The planet has a very primitive form of plate tectonics, and the action of two plates past each other began splitting the surface some 3.5 billion years ago. That set the stage for the formation of the Valles Marineris. At the same time, volcanic activity in the Tharsis region put pressure on the crust as molten lava pushed the region up from below. The combined tectonic activity further broke the crust into fractures and fault regions. In the valleys, the ground sank, and underground water escaped. That caused the ground to drop farther, and landslides and erosion continued to cut away and widen the valley systems. Today, the Vallis Marineris canyons show the marks of ancient floods and continued erosion by the Martian winds.

 

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