People all over the world looked up at the sky in November to spot a phenomenon known as “supermoon.” While you might expect a supermoon to be huge, the difference between a supermoon and a regular moon can actually be hard to spot. For example, the supermoon this week was only 7 percent bigger than usual. Scientist Neil deGrasse Tyson compares this to the difference between a 15-inch (38 cm) pizza and a 16-inch (41 cm) pizza.
So what causes supermoons? The moon’s orbit is shaped like an oval. This means that the moon is not always the same distance from Earth. When the moon gets closer, it looks larger. Perigee is when the moon is the closest to Earth. When perigee happens at the same time as a full moon, the moon looks both bigger and brighter. People have started calling this phenomenon a “supermoon.”
The moon reached perigee this year on November 14. It was just 221, 524 miles (356,509 km) from Earth. This is much closer than its average distance of 238,855 miles (384,400 km) from Earth. The moon has not been this close since 1948. It will not be this close again until 2034.