SomeFacts | Universe

Universe

What does an alien look like?
At the moment, the only aliens we are likely to encounter are very, ...

How are we looking for extra-terrestrial life?
Since possible fossils of microscopic life were found in Martian rock ...

Are there any other planets like Earth?
There is no other planet like Earth anywhere in the solar system. ...

What is DNA?
Dioxyribonucleic acid, the most remarkable chemical in the universe ...

Why is the universe like it is?
The amazing chance that life exists on Earth has made some scientists ...

What is SETI?
SETI is the Search for Extra-Terrestrial Intelligence ...

Where did life come from?
Most scientists think life on Earth began on Earth-in the oceans or ...

Where did the materials of life come from?
It used to be thought that organic chemicals all originated on Earth, ...

What is life made of?
Life is based on complex compounds of the element carbon, known as ...

How did the first galaxies and stars form?
They formed from curdled lumps of clouds of hydrogen and ...

Can we see the Big Bang?
Astronomers can see the galaxies hurtling away in all directions. ...

What is inflation?
Inflation was a period in the first few trillionths of a trillionth ...

How long will the universe last?
It depends how much matter it contains. If there is more than the ...

How do we know what it was like?
We know partly by mathematical calculations, and partly by ...

What was the Big Bang?
In the beginning, all the universe was squeezed into an unimaginably ...

Why is the universe getting bigger?
We can tell the universe is getting bigger because every galaxy is ...

What was there before the universe?
No one has a clue. Some people think there was an unimaginable ocean ...

How many galaxies are there?
With the largest telescopes and most sensitive detectors, we could ...

What is the biggest thing in the universe?
The biggest structure in the universe is the Great Wall-a great sheet ...

What are double stars?
Our Sun is alone in space, but many stars have one or more nearby ...

What are star clusters?
Stars are rarely entirely alone within a galaxy. Most are ...

Where is the Earth?
The Earth is just over halfway out along one of the spiral arms of ...

What is the Milky Way?
The Milky Way is a pale blotchy white band that stretches right ...

What is a spiral galaxy?
A spiral galaxy is a galaxy that has spiralling arms of stars like a ...

What is antimatter?
Antimatter is the mirror image of ordinary matter. If matter and ...

What’s the smallest particle?
The smallest particle inside the nucleus is the quark. It is less ...

What was the first element?
The first element to form was hydrogen, which has the simplest and ...

How was iron made?
Iron was forged in the heart of supergiant stars near the end of ...

How were atoms made?
Atoms of hydrogen and helium were made in the early days of the ...

What are particles?
Particles are the tiny concentrations of energy from which all matter ...

How many black holes are there?
No one really knows. Because they trap light they are hard to see. ...

How big is a black hole?
The singularity at the heart of a black hole is infinitely small. The ...

What happens inside a black hole?
Nothing that goes into a black hole comes out, and there is a point ...

How strong is a planet’s gravity?
The more massive the planet-that is, the more matter it contains the ...

What did Newton discover?
The discoveries of Isaac Newton (1642-1727) include the three ...

What are orbits?
In space, many objects like planets and moons continually circle ...

How do astronomers measure distance?
For nearby stars, they use parallax. With middle distance stars, they ...

How far is it to the nearest star?
The nearest star is Proxima Centauri, which is 4.3 light-years ...

How far away is the Sun?
The distance varies between 91 and 94 million miles from Earth. This ...

What is the farthest star we can see?
The farthest objects we can see in space are quasars, which may be ...

What is a parsec?
A parsec is 3.26 light-years. Parsecs are parallax ...

What is a light-year?
A light-year is 5.88 trillion miles. This is the distance light can ...

What is red shift?
When a galaxy is moving rapidly away from us the waves of light ...

Are the stars getting farther away?
Analysis of red shifts has shown us that every single galaxy is ...

What are neutron stars?
Neutron stars are all that remains of a supergiant star after a ...

What is a white dwarf?
White dwarfs are the small white stars formed as stars smaller than ...

What are the oldest stars?
The oldest stars we know of are not stars at all, but simply look ...

What is a red giant?
Red giants are the huge, cool stars formed as surface gas on ...

How old are the stars?
Stars are dying and being born all the time. Big bright stars live ...

What is a pulsar?
Pulsars are stars that flash out intense radio pulses every ten ...

What colour are stars?
It depends how hot they are. The colour of medium-sized stars varies ...

What makes stars twinkle?
Stars twinkle because the Earth's atmosphere is never still, and ...

How hot is a star?
The surface temperature of the coolest stars is below 6,300°F ...

What makes stars glow?
Stars glow because the enormous pressure deep inside generates ...

What are constellations?
Constellations are small patterns of stars in the sky, each with its ...

What is the biggest star?
The biggest stars are the supergiants. Antares is 700 times as big as ...

How many stars are there?
It is hard to know how many stars there are in the universe, for the ...

How are stars born?
Stars are born when clumps of gas in space are drawn together by ...

Why do some stars throb?
The light from variable stars flares up and down. "Cepheid" are big ...

Who found Neptune?
Two mathematicians, John Couch Adams in England and Urbain le Verrier ...

How long is a year on Neptune?
Neptune is so far from the Sun-2.8 billion miles (4.6 billion km) at ...

Why is Neptune green?
Neptune is greeny blue because its surface is completely covered in ...

What’s an asteroid?
Asteroids are the thousands of rocky lumps that circle round the Sun ...

What’s strange about Uranus?
Unlike any of the other planets, Uranus does not spin on a slight ...

What is a meteorite?
Meteorites are lumps of rock from space big enough to penetrate the ...

How big is Pluto?
Pluto is very small, which is why it was so hard to spot. It is five ...

Could you land on Jupiter?
No. Even if your spaceship could withstand the enormous pressures, ...

How big is Jupiter?
Very big. Even though Jupiter is largely gas it weighs 320 times as ...

What is Jupiter’s red spot?
The Great Red Spot or GRS is a huge swirling storm in Jupiter's ...

How many moons has Jupiter?
Jupiter has 16 moons-four big ones, discovered by Galileo as long ago ...

How fast does Jupiter spin?
Jupiter spins faster than any other planet. Despite its huge size, it ...

Why are astronomers excited about Titan?
Saturn's moon Titan is very special because it is the only moon in ...

How many moons has Saturn?
Saturn has at least 18 moons, including lapetus, which is black on ...

What is the Cassini division?
Saturn's rings occur in broad bands labelled with the letters A to G. ...

How heavy is Saturn?
Saturn may be big, but because it is made largely of liquid hydrogen, ...

How windy is Saturn?
Saturn's winds are even faster than Jupiter's and roar round the ...

What are the giant planets made of?
Jupiter and Saturn are made largely of hydrogen and helium. On ...

Why is Venus called the Evening Star?
Venus reflects sunlight so well it shines like a star. But because it ...

What is the air on Venus?
Venus's atmosphere would be deadly for humans. It is very deep, so ...

How hot is Mercury?
Temperatures on Mercury veer from one extreme to the other because it ...

Could you breathe on Mercury?
Not without your own oxygen supply. Mercury has almost no atmosphere ...

What are the inner planets made of?
Each of the inner planets is formed a little bit like an egg-with a ...

Is there life on Mars?
The Viking landers of the 1970s found not even the minutest trace of ...

Why is Mars red?
Mars is red because it is rusty. The surface contains a high ...

What’s frightening about Mars’s moons?
One night American astronomer Asaph Hall got fed up with studying ...

What are solar flares?
Flares are eruptions from the Sun's surface that fountain into space ...

What is the solar wind?
The solar wind is the stream of radioactive particles constantly ...

How old is the Sun?
The sun is a middle-aged star and probably formed about five billion ...

What makes the Sun burn?
The Sun gets its heat from nuclear fusion. Huge pressures deep inside ...

How hot is the Sun?
The surface of the Sun is a phenomenal 11,000°F (6,000°C), and would ...

What is the Sun’s crown?
The Sun's crown is its corona, its glowing white hot atmosphere seen ...

How big is the Sun?
The Sun is a small to medium-sized star 0.86 million miles (1,392,000 ...

What is a solar eclipse?
A solar eclipse is when the Moon comes in between the Sun and the ...

What’s inside the Moon?
The Moon's mantle is now very cool compared to the Earth's. The ...

Why does the sea have tides?
The Moon's gravity draws the oceans into an oval around the Earth, ...

What is a harvest moon?
The harvest moon is the full moon nearest the autumnal equinox (when ...

Why does the moon look like cheese?
The moon looks like cheese because it is full of holes, and sometimes ...

What is moonlight?
The Moon is by far the brightest thing in the night sky. But it has ...

What is a lunar eclipse?
As the Moon goes round the Earth, sometimes it passes right into ...

How long is a month?
It takes the Moon 27.3 days to circle the Earth, but 29.53 days from ...

What are the Moon’s seas?
The large dark patches visible on the Moon's surface are called seas, ...

Who were the first men on the moon?
The first men on the Moon were Neil Armstrong and Buzz Aldrin of the ...

What’s so special about the Earth?
The Earth is the only planet with temperatures at which water can ...

Who was Copernicus?
In the 1500s, most people thought the Earth was fixed in the center ...

What shape is the Earth?
The Earth is not quite a perfect sphere. Because it spins faster at ...

How big is the Earth?
Satellite measurements show it is 24,870 miles (40,024 km) around the ...

What is the Earth made of?
The Earth has a core of iron and nickel, and a rocky crust made ...

How old is the Earth?
The Earth is about 4.6 billion years old. The oldest rock is about ...

Why does the Earth spin?
The Earth spins because it is falling around the Sun. As the Earth ...

How long is a day?
A day is the time Earth takes to turn once. The stars come back to ...