The night sky has a beautiful surprise in store for us this Wednesday with a particularly large and bright Moon. This celestial phenomenon, known as a supermoon, offers a spectacle accessible to all astronomy enthusiasts.
Our natural satellite does not follow a perfectly circular path around the Earth, but rather a slightly oval orbit called an ellipse. This particularity means that the distance between the Moon and our planet constantly varies. When the full moon coincides with the point of its orbit closest to Earth, the perigee, we witness what astronomers call a supermoon. NASA specifies that this configuration can make the Moon appear up to 14% larger and 30% brighter than at its apogee, the farthest point in its orbit.
This November supermoon is particularly notable as it represents the closest approach of the year, at a distance of only about 357,000 kilometers (approximately 222,000 miles). It's part of a series of three annual supermoons, with October's already having displayed its show, while a final one is expected in December. Astronomer Lawrence Wasserman of the
Lowell Observatory explains that this proximity can slightly influence tides, although this effect generally remains imperceptible to most of us.
To fully enjoy the phenomenon, no special equipment is needed, but you'll need to rely on favorable weather conditions. Shannon Schmoll, director of the
Abrams Planetarium at
Michigan State University, points out that the difference in apparent size can be difficult to perceive with the naked eye without a point of comparison. The ideal approach is to compare successive observations or photographs taken at different times to truly appreciate the variation in dimensions.
These celestial events occur several times a year, offering everyone the opportunity to contemplate the wonders of our Solar System. Each supermoon reminds us of the dynamics of the Earth-Moon system and the importance of looking up at the sky to observe these astronomical phenomena accessible to all.
The visual perception of supermoons
Our eye has difficulty perceiving variations in the Moon's size without reference points. The human brain tends to overestimate the lunar size when it's near the horizon, a psychological effect known as the moon illusion, which has nothing to do with the supermoon itself.
The difference in brightness, on the other hand, is more easily perceptible. A 30% increase in brightness corresponds to a difference of about 0.3 astronomical magnitudes, which is sufficient for some attentive observers to notice a more brilliant Moon than usual.
Astronomy photographers often use specific techniques to capture the supermoon, such as using telephoto lenses and comparing it with landscape elements. These images allow for clear visualization of the size difference compared to a standard full moon.
Regular observation of the lunar sky helps develop sensitivity to these variations.