Tatooine's Two stars
Total eclipses are a luxury of our time. Future beings will not be able to experience this magical natural phenomenon which turns day into night.
From my class notes:
The Moon’s average distance from Earth increases by 3.8 centimeters per year. Such a precise value is possible due to Apollo laser reflectors which astronauts left behind during lunar landing missions. Eventually, the Moon’s distance will increase so much that it will be too far away to produce total eclipses of the Sun—they will all be annular.’
More factoids after the break.
Fact: About half the solar systems in the known universe are binary systems! (Two stars)
Earth is slowing down!
The reason for Earth’s rotational slowdown in the first place are ocean tides, which are caused by the gravitational pull of the Moon and, to a lesser extent, the Sun. But as the tides are attracted to the Moon, the oceans appear to rise and fall while Earth rotates beneath them, which generates friction between water and ocean bottoms, primarily in shallow seas. This tidal friction gradually transfers angular momentum and rotational energy from Earth to the Moon’s orbit. Earth looses energy and slows down while the Moon gains the energy and consequently it’s orbital period and distance from Earth increase by slowly spiraling outward. This outspiraling has been occurring for a very long time. Fossil evidence (corals, tidal layers) clearly shows that earth’s day was shorter than now: about 18.5 hours some 500 MY ago, about 17 hours 1 BY ago, and about 11.5 hours 2 BY ago. Tidal friction has also caused the Moon to keep the same hemisphere toward Earth.
The theory of tidal friction was later developed by George Darwin (son of the famous Naturalist) in the 1880s. He used it to predict the future of the Earth-Moon system: in several BY (Billion Years) the month would be some 55-60 days long and Earth will have slowed down to rotate at that same period, so the same hemisphere of Earth faces the Moon, and lunar tides no longer generate friction. But the tides raised by the sun on Earth cause it to further slow down, so its rotational period will become longer than the Moon’s orbital period. This causes the Moon to approach Earth, reversing its past orbital outspriral into an inspiral. As it comes closer to Earth over another few BY, it will eventually raise fierce ocean and land tides, and Earth will raise even larger tides on the Moon. Both will heat up and ultimately coalesce.
