Have you ever looked up at the night sky and noticed the full moon glowing unusually large and luminous? If that’s happening tonight—on June 11—you’re witnessing a supermoon.
While it might feel like the moon is putting on a cosmic show just for us, there’s solid science behind this celestial spectacle. Let’s dive into what really makes a supermoon “super.”
What Is a Supermoon?
A supermoon occurs when a full moon aligns with its closest approach to Earth in its elliptical orbit, a point known as perigee. “That’s why the moon can seem noticeably larger and brighter—up to 14% bigger and 30% more radiant—compared to when it’s farthest from Earth.”
Understanding the Moon’s Path Around Earth
Contrary to what many of us imagine, the moon’s orbit around Earth isn’t a perfect circle—it’s an ellipse, or an oval-shaped path. This means that as the moon orbits Earth every month, its distance from us constantly changes.
- Perigee: The point in the moon’s orbit where it is closest to Earth (about 356,500 km away).
- Apogee: when the moon reaches its farthest distance from Earth—around 406,700 kilometers away.”
Why Does It Look So Bigger and Brighter?
Two main factors are at play:
1. Closer = Brighter and Bigger
Since the moon is physically closer to us during a supermoon, it reflects more sunlight back to Earth, appearing brighter. Its proximity also makes it look larger in the sky, especially compared to a “micro moon” (a full moon at Apogee).
2. The Moon Illusion
There’s another curious effect happening—one that’s all in our heads. When the moon is near the horizon, our brains compare it to buildings, trees, or mountains, making it appear even larger than it is. This is called the Moon Illusion, and it can make the supermoon seem even more dramatic.
Can You Really Tell the Difference?
To the casual observer, the size difference between a regular full moon and a supermoon might not be immediately obvious. But if you photograph both and compare them side by side, the change is quite noticeable. And for stargazers, it’s a perfect excuse to step outside and enjoy one of nature’s simplest but most magical phenomena.
So, What’s the Big Deal?
While a supermoon isn’t rare (we usually get 3–4 per year), it never fails to capture attention—and for good reason. It reminds us of our place in the universe, sparks curiosity in young and old alike, and brings a touch of wonder to our everyday lives.
So tonight, when you see the moon rising—big, bold, and bright—know that there’s real science behind beauty. And maybe, just maybe, take a few moments to pause and enjoy the show.