Welcome to the space explorer learning resource page!

The sun constitutes 99.86% of all of the mass in our solar system and has a ginormous diameter of 870,000 miles!

To put this into perspective, you could fit about a million Earths inside the sun, so needless to say it's pretty big!

The sun is what's called a sequence star, which is a sphere composed of hydrogen and helium gasses that fuse together at the sun's core, producing a huge amount of light and heat energy; at its centre the sun's temperature can be as much as 15 million degrees and even from Earth, which is over 90 million miles away, the sun is still pretty bright!
 

Mercury is not only the smallest planet in our solar system, but also the closest planet to the sun. You might think this would make it the hottest planet, but, in fact, it's the second hottest after Venus.

This is because, unlike some other planets, Mercury does not have an atmosphere to trap the sun's heat, so although it gets very hot on the side exposed to the sun (up to 470 degrees!), the side in the shade can be as cold as -173 degrees!

Future space explorers will need a large and varied wardrobe to travel here!

 

Venus is the second closest planet to the sun and the hottest planet in our solar system, with an average temperature of 462 degrees!

Although it was once thought Venus was a tropical paradise, scientists have since discovered that its dense atmosphere and high carbon dioxide concentration traps heat, causing the temperature to rise in what's known as the greenhouse effect.

Scientists believe Venus was once covered in oceans, but because of rising temperatures these oceans have since evaporated. So, take note earthlings, we must protect our planet and prevent greenhouse gasses having the same effect on Earth!

 

Earth, or as we know it, home, is the third planet from the sun and the fifth largest planet.

As far as we know, it's the only planet to host life (although who knows what we might discover in years to come!). That's because Earth has all the ingredients needed in order for life to thrive, which include the right temperature, water, sunlight, nitrogen and oxygen.

Earth is the only planet in our solar system not named after the Roman gods and goddesses. The word Earth in fact comes from the Old English 'Ertha, meaning land or ground, which is perhaps not so fitting as 70% of the Earth's surface is actually covered in water!

It takes the planet 365.25 days to orbit the sun, giving us a year, but because this isn't a round number, every four years we add a day to the calendar. We call this a leap day and the year it's added to is called a leap year!

 

The Hubble Space Telescope is an enormous telescope that orbits the Earth and takes photographs of our universe.

It was launched into space in 1990 and has taken some of the most detailed images we've seen, giving scientists a better understanding of space and time.

The telescope was named after Edwin Hubble, one of the most important astronomers of all time who brilliantly discovered the existence of other galaxies!

Should anything go wrong with the Hubble it's the only telescope designed to be serviced in space by astronauts, which can be no easy task!

 

Sputnik was the first man-made object to orbit (travel around) the Earth! It was launched into space by the Soviet Union in 1957 and orbited the Earth 1,440 times over three months, before it re-entered the Earth's atmosphere and burned up.

The United States were surprised by the launch of Sputnik and, not wanting to fall behind, started spending more money on their own space research and so began a race between the two nation-states to see who could be the first to send humans into space and land on the moon...

 

Mars is the fourth planet from the sun and has a surface temperature of between -153 and 20 degrees.

Named after the Roman god of war, it has a vivid red colour due to the high content of iron in its surface rock.

For a long time now, Mars has been considered the most likely planet outside of our own to host life, as scientists have spotted evidence the planet has water. However, so far, despite several spacecraft successfully landing on and exploring the red planet, no life forms have been discovered.

Fun fact: unlike Earth, Mars has two moons instead of one! They're known as Phobos and Deimos after the Greek mythological twin sons of Ares, the god of war, who was known to the Romans as Mars.

 

The Viking 1 space probe was launched in 1975 and made history when it became the first spacecraft to successfully land on the surface of Mars. Originally meant to function for 90 days, Viking 1 managed to live on Mars for more than 6 years!

It gathered photographs, scientific data and did on the spot tests, which has given us a much better understanding of the planet Mars.

We now know that Mars has an iron-rich clay surface with volcanic soil, a thin, dry atmosphere and there's convincing evidence Mars once had river beds and flooding, too.

The largest of all of the planets, Jupiter is fittingly named after the Roman god of gods.

To give you an idea of its enormous size, you would have to line 11 Earths up next to each other in order to stretch from one side of Jupiter to the other and you could fit 317 Earths inside the planet.

A day on Jupiter lasts just under 10 hours, while a year lasts the equivalent of 11.86 Earth years! Like its neighbour Saturn, Jupiter also has rings that are made up of dust particles.

Although these rings look faint in photographs, they're in fact between 2000 and 12,500km thick!  That's a whole lot of dust!

With 67 moons, Jupiter has the most of any planet in our solar system.

Saturn is the sixth planet from the sun and the second largest planet in our solar system. Although not quite as big as Jupiter, you would have to line up nine earths side by side to span Saturn's vast diameter.

Of all the planets, Saturn is perhaps the easiest to identify because it has lots of very visible rings. These are made up of lumps of rock and ice and appear grey and beige in photographs.

So far scientists have identified 53 moons on Saturn, but it's believed there might be at least 9 more moons yet to be discovered.

Because Saturn is a gas-giant planet it does not have a solid surface like Earth, so life here would be pretty difficult! Some of Saturn's moons, however, do have conditions that could potentially support life.

The Cassini-Huygens probe was a space probe sent to study Saturn. It was launched in 1997 and stayed active in space for nearly 20 years, where it took detailed photographs and gathered important and fascinating data!

It spent 13 years orbiting Saturn, before the mission ended in 2017, when the probe ran out of fuel and so the decision was made to send it into Saturn's upper atmosphere, where it burned up, preventing it from contaminating Saturn's moons.

Uranus is the seventh planet from the sun and the third widest (it would take Uranus approximately 4 earths lined up side by side to stretch across the diameter of Uranus).

The planet is a light blue colour because as well as helium and hydrogen in its atmosphere, it also has methane, which has a blue hue. Like Jupiter and Saturn, Uranus also has rings. There are 13 rings in total and they are made up of everything from small dust particles to large boulders, but they're very hard to see in photographs.

Uranus is what's called an ice-giant because it is extremely cold and windy and with a temperature of between -226 and -150 degrees, it's the coldest of all the planets!

Uranus has 27 small moons, which have all been named after William Shakespeare and Alexander Pope characters!

The planet is unique because it rotates on its side, which scientists believe may have occurred as a result of a huge rock colliding with the planet and knocking it on its side!

 

Neptune is the eighth planet from the sun and the most distant planet in our solar system. Because it is so far from the sun, the planet is dark, cold and very windy.
 
In fact, Neptune has supersonic winds that can reach speeds of 1,200 miles per hour! To give you an idea, this is 9 times stronger than the wind we experience on Earth!
 
Like Uranus, Neptune also has methane present in its atmosphere, giving it a blue colour, but unlike Uranus which is pale blue-green, this planet is a much darker royal blue that looks like the ocean, which is very fitting considering it's named after the Roman god of the sea!
 
You might not be able to see them in photographs, but like the other gas planets, Neptune also has rings - six of them - made up of small rocks and dust.