Which is hotter: the centre of the Earth or surface of the Sun?
Nick McDonald
The temperature at Earth’s core and at the surface of the Sun are very similar. We can estimate the Sun’s surface temperature by studying the colour of the surface, together with the continuous spectrum emitted by the Sun. When a piece of metal is heated it starts glowing red, then changes progressively to bluish-white as it gets hotter. Similarly, the colour of the Sun’s surface is an indicator of temperature. Using this information, we can get a reasonable estimate for the surface temperature of around 5,778 Kelvin, or 5,505 degrees Celsius. The core of the Earth is mainly composed of an alloy of the metals iron and nickel under very high pressure. Scientists can examine the properties of materials such as iron under pressure in the laboratory. Using such methods, we can calculate that the temperature at the core is about 5,700 Kelvin, or 5,430 degrees Celsius.
WHY DO SOME BEACHES HAVE SAND, WHILE OTHERS HAVE PEBBLES?
Joe Saint
There are many factors that determine what kind of beach occurs on any part of the coast. The shape of the coastline, the local geology and the prevailing weather conditions are all significant factors. The size of particles that make
