Basically, when the North Pole is pointing towards the Sun, the northern hemisphere experiences summer and the southern hemisphere experiences winter.

During the summer, the day lasts longer and the Sun climbs higher in the sky; while in winter, the climate becomes generally cooler, the days are shorter and the Sun appears lower in the sky.

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But the most remarkable thing about our planet is its diversity.

Not only are there an endless array of plants, animals, avians, insects and mammals, but they exist in every terrestrial environment.

By 5 billion years from now, the Sun will become a red giant, expanding to 250 times to a radius of roughly 1 AU (150 million km).

In this scenario, Earth will move to an orbit of 1.7 AU (250 million km) from the Sun, will escape envelopment, but will also be rendered completely uninhabitable.

Earth’s axis is tilted 23.439281° away from the perpendicular of its orbital plane, which is responsible for producing seasonal variations on the planet’s surface with a period of one tropical year (365.24 solar days).

In addition to producing variations in terms of temperature, this also results in variations in the amount of sunlight a hemisphere receives during the course of a year.

Within 1 billion years, all water will be gone and the average surface temperature will reach 70 °C (158 °F).

Earth is expected to be effectively habitable for about another if the nitrogen is removed from the atmosphere.

The theory maintains that plant evolution, animal evolution and the major geological changes to the earth unfolded over billions of years.