Due to thermal energy, some of the molecules at the outer edge of the Earth's atmosphere have their velocity increased to the point where they can escape from the planet's gravity. This results in a slow but steady leakage of the atmosphere into space. Because unfixed hydrogen has a low molecular weight, it can achieve escape velocity more readily and it leaks into outer space at a greater rate.[61] For this reason, the Earth's current environment is oxidizing, rather than reducing, with consequences for the chemical nature of life which developed on the planet. The oxygen-rich atmosphere also preserves much of the surviving hydrogen by locking it up in water
The reasons why have to do with tides and conservation of energy and angular momentum. Measurements have been collected now for over 25 years, and it is clear that the Moon's orbit is slowly growing larger and that the Moon is moving away from the Earth. The net result is that the Moon is receding from the Earth at about 4 centimeters a year.
However, astronomers have predicted that when the Sun enters the red giant phase in around 5 billion years - during the red giant phase of the Sun - both Earth and Moon will be affected by the Sun's extended atmosphere and will aproach again. Then the Moon will swing ever closer to Earth until it reaches a point 11,470 miles (18,470 kilometers) above our planet, a point termed the Roche limit. The result: Moon will be torn to pieces and will be scattered to form a spectacular 23,000-mile-diameter (37,000-kilometer) Saturn-like ring of debris above Earth's equator.
The Earth is slowing down

As a result of variation in gravitational forces due to the moon, the sun and other planets in the solar system, displacements of matter in different in different parts of the planets and other excitation mechanisms, the rotational speed of the Earth about it's axis varies in time. Recently, days have been getting shorter by hundredths of a second, which implies that the angular velocity of the Earth has been increasing. The factors causing this increasing in the Earth's rotational velocity have not been determined. The rotation data shows oscillations over several different timescales. The one with the largest variation is seasonal: Earth slows down in January and February