Our Moon may seem ordinary, but it quietly keeps Earth stable. It controls the tides, slows our planet’s rotation, and helps maintain the rhythm of life. But what if it suddenly disappeared and was replaced by something much larger?Imagine looking into the night sky and seeing not the familiar Moon, but Kepler-22 b, a giant world discovered hundreds of light-years from Earth. Instead of a small gray disk, an enormous planet would dominate the heavens, appearing many times larger than the Moon we know today.At first, the sight would be breathtaking.Kepler-22 b was the first exoplanet discovered inside the habitable zone of a Sun-like star. Scientists estimate that it is about 2.4 times wider than Earth and could contain nearly nine times Earth’s mass. Some researchers even suspect it may be covered almost entirely by oceans, making it a brilliant blue world reflecting vast amounts of sunlight.But beauty wouldn’t last long.Unlike our relatively lightweight Moon, this enormous planet would exert an incredible gravitational pull on Earth. Instead of quietly orbiting us as the Moon does today, Kepler-22 b would force Earth into something entirely different, a binary planet system. Rather than one planet orbiting the other, both worlds would circle a shared center of gravity.That single change would transform everything.The first victims would be Earth’s oceans. Tides would no longer rise by a few meters. They could tower hundreds of meters high, swallowing coastlines and pushing seawater deep into continents. Entire cities would disappear beneath walls of water that arrived with terrifying regularity.The oceans wouldn’t be the only things moving.Earth itself would constantly flex under the giant planet’s gravity. The crust would bend and stretch, triggering earthquakes stronger than anything recorded in human history. Volcanoes across the globe would erupt as pressure built beneath the surface, filling the atmosphere with ash and toxic gases.Life on Earth would quickly become nearly impossible.Ironically, Kepler-22 b might benefit from the move.In its original solar system, astronomers believe the planet follows an elliptical orbit, moving closer to and farther from its star during each year. Those changing distances could create dramatic swings in temperature and weather. Without a large moon of its own to stabilize its tilt, its climate may be unpredictable for millions of years.Placed in our Solar System, things could eventually improve.Earth’s gravity could help stabilize the giant world’s rotation, while the steady sunlight from our Sun might create a more consistent climate over incredibly long timescales. If Kepler-22 b truly is an ocean planet, some regions could eventually become more hospitable than before.Unfortunately, humanity would never live long enough to find out.The greatest danger wouldn’t be the floods or the earthquakes. It would be gravity itself.As Earth and Kepler-22 b orbited each other, their relationship would become increasingly unstable. Tiny changes in their orbits would gradually pull the two worlds closer together. Over time, the giant planet would loom larger in our sky, filling more and more of the horizon with each passing year.Eventually, there would be nowhere left to run.The collision between Earth and a planet nearly nine times as massive would release an unimaginable amount of energy. Mountains would vaporize instantly. Oceans would boil away. The impact would tear both worlds apart, creating a cloud of molten rock that would orbit the Sun where Earth once existed.There would be no survivors.As destructive as this scenario sounds, replacing the Moon with Kepler-22 b isn’t even the worst possibility. There are worlds in our galaxy that are even hotter, denser, and more hostile. One of them is 55 Cancri e, a planet so extreme that it makes Kepler-22 b seem almost welcoming. And if that world ever took the Moon’s place, Earth’s fate would become even more terrifying.