Physics P1 - complete notes

Module P1 - The Earth in the Universe

The Solar System

• The solar system is around 5 billion years old, as is Earth
• The Universe is at least 14 billion years old
• Asteroids are rocks and rubble, and comets are balls of rock, dust and ice which have a 'tail' (melted ice), very elongated elliptical orbit.

Radiation in space

• Surface temperature of a star can be estimated from its colour
• Parallax is used to measure distances to stars. Astronomers take pictures of the sky six months apart (Earth at opposite sides of orbit)
• Relative brightness can be used, but the atmosphere absorbs a lot of light and light pollution from Earth makes it difficult to see dim objects. Telescopes can be placed in space instead.
• We see stars/galaxies as they were in the past - radiation takes a while to reach us.

Redshift

• The more distant a galaxy, the redder the light it emits is. The greater the redshift, the faster it is moving away. From observations of other galaxies we know the more distant the galaxy the faster it moves away from us. This proves the Universe is expanding.

Rock cycle

• When lava from volcanoes sets, it forms new rock.
• Fossils provide evidence for this; rocks must have built up around them once they were dead.
• The age of the Earth can be estimated from old rocks.
• Particles from sea erosion get washed into sediment and form sedimentary rocks.

Alfred Wegener

• Fossils of very similar rocks and plants found on opposite sides of Atlantic Ocean. Coastlines of South…