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| Pregunta | Respuesta |
| THE SOLAR SYSTEM Structure of our Solar System | SUN Mercury Venus Earth Mars Asteroid Belt Jupiter Uranus Neptune dwarf planets, comets, dust... also orbit the sun, as well as the moons of planets |
| THE SOLAR SYSTEM Stars vs. Planets | Stars are huge (the sun's diameter is over 100x bigger than the Earth's), extremely hot and much further away. Stars also radiate lots of light. Planets are much smaller and the one's in Solar system are much closer than any stars- apart from our Sun. Planets also just reflect sunlight that falls on them. |
| THE SOLAR SYSTEM How was it formed? | Formed over a really long time from clouds of dust and gas. For some reason (nearby star exploding?) one cloud got compressed. Once the particles were closer together, gravity pulled everything until the whole cloud collapsed in on itself. At the centre, particles formed a protostar. when hot enough, hydrogen nuclei joined to create Helium: fusion. Fusion gives out masses of heat and light - our Sun's energy. Elements in the clouds with heavier atoms than 'H' and 'He' were also formed by the fusion of other nuclei. Material from the clouds containing hydrogen, helium & heavier elements clumped together to form planets. |
| THE SOLAR SYSTEM How old is our Solar System? | Around 5000 million years old. The oldest rocks on Earth are meteorites (we think these were formed around the birth of the Solar System). These are around 4500 million years old, so the Solar System has to be at least that old. |
| THE SOLAR SYSTEM Asteroids and Comets | Asteroids and comets were made of stuff left over from the formation of the Solar System. The asteroids between Mars and Jupiter didn't form a planet but stayed as smallish lumps of rubble and rock. Comets are balls of rock, dust and ice which orbit the sun in elongated ellipses. When comets get near the sun their ice begins to melt, leaving a bright tail of gas. |
| BEYOND THE SOLAR SYSTEM Galaxies | Our Sun is one of thousands of millions of stars that make up the Milky Way Galaxy. The distance between neighbouring stars in a galaxy is usually millions greater than the difference between planets. Every galaxy has thousands of millions of stars, and the Universe has thousands of millions of galaxies (galaxies are often millions of times further apart than the stars within them) |
| BEYOND THE SOLAR SYSTEM Light Years | Light years = the distance that light travels in a vacuum in one year Kilometres are far too small to measure the enormous distances outside the Solar System. So instead we use light years.Light travels at 300 000km/s. 1 light year = 9 460 000 000 000 km approx |
| LOOKING INTO SPACE Parallax and Distance to a Star | Astronomers take pictures of the sky 6 months apart (when the Earth is on opposite sides of its orbit). The apparent movement of a star, between the 2 photos lets you work out the distance to the star. The bigger the movement, the closer the star. |
| LOOKING INTO SPACE Brightness and Distance to a Star | Measuring brightness can give an estimation to how far away a star is. Unfortunately, a bright star could either be relatively close or just really bright. Astronomers know how much radiation certain types of stars should be emitting so can calculate the distance to them. |
| THE LIFE OF THE UNIVERSE Redshift | When a galaxy moves away from us, the wavelength of the light changes, becoming longer- causing the light to become redder. This is called red shift. By seeing how much light has been redshifted, you can calculate how fast galaxies are moving. The more distant a galaxy, the faster it moves away. This provides evidence that the Universe is expanding. |
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