Drag the Moon toward Earth. Watch the tides flood the coasts and the sky turn permanent eclipse.
Right now the Moon is 60 Earth radii away. It is also moving away at 3.8 centimeters per year. Laser reflectors left by Apollo astronauts measure this. The Moon steals angular momentum from Earth. Each year, our day gets a tiny bit longer. In a billion years, a day will be 25 hours. The Moon will be farther. Total solar eclipses will no longer be total. The Moon will look too small to cover the Sun.
If the Moon were closer, the opposite happens. Tides get bigger. Tide height scales as the inverse cube of distance. Half the distance means eight times the tide. At 30 Earth radii, high tide would be 80 meters deep. Coastal cities would not exist. The entire Atlantic seaboard would be underwater twice a day. There would be nowhere to build.
At 10 Earth radii, the Moon would fill the sky. Solar eclipses would happen every month and last for hours. The night would be bright enough to read by. But the tides would be apocalyptic. The tidal forces would flex the crust. Volcanoes would erupt constantly. Earth would become a volcanic world.
Below 2.44 Earth radii is the Roche limit. Inside that distance, tidal forces tear the Moon apart. It would become a ring around Earth, like Saturn. We would lose the Moon forever. We would get a beautiful ring. But no more tides, no more eclipses, no more werewolves. The tradeoff is not worth it.
Tidal friction. The Moon pulls on Earth's oceans, creating a tidal bulge. Earth's rotation drags this bulge ahead of the Moon. The bulge's gravity pulls the Moon forward, boosting its orbit. The Moon gains about 3.8 cm per year. Earth loses rotation speed. Our day lengthens by 1.7 milliseconds per century.
The distance inside which a celestial body held together only by its own gravity is torn apart by tidal forces. For Earth and our Moon, it's about 2.44 Earth radii. If the Moon ever got inside this distance, it would shatter and form a ring.
Yes. At half distance, the Moon would appear twice as wide and four times as bright. Nights would be like twilight. You could read outside at midnight. Astronomers would hate it. Stargazing would be ruined by moonlight.
It wouldn't crash. It would first cross the Roche limit at 2.44 Earth radii and shatter into a ring. Then the ring debris would rain down over millions of years. The sky would turn red. Surface temperatures would rise. It would be bad.