What is the meaning of 'kalpa' in Buddhism, and how is it measured?

This is one of my main concerns. What did Buddha actually mean by 'kalpa'? I know Buddha said that the Earth will die by fire, and then all beings will be born in the Abhasara loka. I think this may refer to the sun expanding in the next 5 billion years, meaning the Earth could remain suitable for life for around 5 to 8 billion years (totally). So, how does this apply to the calculation of a kalpa? Did Buddha use extraordinary examples to teach how long this time period is? If not, what about the extremely long year examples? What are the types of kalpas? I need a trustworthy answer because this is one of the main arguments in Buddhism.