Moon and Pleiades conjunction September 22nd 2024

The Moon and the Pleiades, also known as the Seven Sisters, are two of the most obvious objects in the night sky. The Moon, with its ever-changing phases, is a constant companion for skywatchers. The Pleiades, a stunning open star cluster in the constellation Taurus, has been admired since ancient times for its sparkling beauty. When these two celestial objects come into close proximity, it creates a scene of extraordinary beauty and fascination. The photo above is one of my own, being two images combined - it's a simulation of what you should see.

Some facts about the Moon and Pleiades conjunction September 22nd, 2024

The Moon has an apparent diameter of about 0.5 degrees in the sky. This is roughly the size of your thumbnail at arm's length.

The Pleiades (Messier 45) open star cluster appears much larger in the sky than the Moon. The Pleiades cover an area approximately 2 degrees in diameter. However, the main grouping of brighter stars that people typically notice is about 1 degree across, but because the stars are spread out, the cluster seems larger.

So, in terms of apparent size:

If you're looking at the core of the Pleiades, where the brightest stars are most densely packed, it's roughly twice the diameter of the Moon in the sky.

Considering the entire extent of the Pleiades, including the fainter stars and the surrounding nebulosity, it's about four times the diameter of the Moon.

Keep in mind that while the Pleiades look large and spread out, they are made up of many stars, whereas the Moon is a single solid body. The actual physical size of the Pleiades is immensely larger than the Moon, but this comparison is about how they appear from our viewpoint on Earth.

The challenge of capturing the Moon and Pleiades together

One of the primary reasons why photographing the Moon and Pleiades together is so challenging is the difference in brightness between the two objects. The Moon, especially when it is in a phase like the waning gibbous, is incredibly bright. The Pleiades, on the other hand, are faint and delicate. To capture both in the same frame requires careful planning and precise camera settings.

Typically, photographing the Moon requires a short exposure time to avoid overexposing its bright surface. This is usually in the range of 1/125th to 1/250th of a second, depending on the phase and the brightness of the Moon. On the other hand, capturing the Pleiades requires a much longer exposure to bring out the faint stars, often in the range of several seconds to even a minute.

Balancing these two extremes in a single photograph is a test of both your technical skills and your patience. One technique that can help is to take multiple exposures at different settings and then blend them together in post-processing. This allows you to capture the detail and brightness of the Moon, while also bringing out the faint stars of the Pleiades. It's a labor-intensive process, but the results can be stunning.

Below: The Pleiades captured by Richard Harris, 3 hours in grayscale for contrast

Why these events are fun

Despite the challenges, or perhaps because of them, photographing the Moon and Pleiades together is incredibly fun. There's a sense of accomplishment that comes from overcoming the technical hurdles and capturing a beautiful image. But beyond the technical aspects, there's something deeply satisfying about witnessing and recording these celestial dances.

One of the reasons these events are so enjoyable is their rarity. While the Moon and the Pleiades do come together in the sky from time to time, it's not an everyday occurrence. Each encounter is unique, with different phases of the Moon and different positions of the Pleiades creating a new visual experience. This rarity makes each successful photograph feel like a special achievement.

There's also the sheer beauty of the scene. The contrast between the bright, cratered surface of the Moon and the delicate, sparkling stars of the Pleiades creates a visual feast for the eyes. It's a reminder of the vastness and complexity of the universe, and of our own small place within it. For many amateur astronomers, these moments of awe and wonder are what make stargazing so rewarding.

During the morning hours of Sunday, Sept. 22, skywatchers across much of the western US will be treated to a particularly special event. A waning gibbous moon, 75 percent illuminated by the sun, will cross in front of the Pleiades. This is one of the most noteworthy and popular of all star clusters in the sky. The Moon and Pleiades dance together, creating a celestial spectacle that is both challenging and exciting to photograph.

For those in the western US, this event is a prime opportunity to try your hand at capturing this beautiful encounter. With the Moon being 75 percent illuminated, it will be bright but not overwhelmingly so, making it a good opportunity to practice balancing the exposure between the Moon and the Pleiades.

As you set up your camera and telescope, take a moment to appreciate the rarity of what you're about to witness. These events don't happen every day, and each one is a chance to see the night sky in a new and beautiful way. Whether you're an experienced astrophotographer or a beginner, the thrill of capturing the Moon and Pleiades together is something that never gets old.

The joy of post-processing two completely different objects in the same frame!

Once you've captured your images, the fun doesn't stop there. Post-processing is where you can really bring out the beauty of the Moon and Pleiades. Using software like Adobe Photoshop or Lightroom, you can blend your multiple exposures to create a balanced image that showcases both the bright details of the Moon and the faint stars of the Pleiades.

Start by stacking your images to reduce noise and improve the overall quality. Then, use layer masks to combine the different exposures, bringing out the best features of each one. Adjust the levels and curves to enhance the contrast and bring out the details. Pay special attention to the color balance, as the Moon can sometimes introduce a yellow or blue tint to your images.

Don't be afraid to experiment with different techniques and settings. Post-processing is as much an art as it is a science, and there's no one right way to do it. The goal is to create an image that captures the beauty and wonder of the night sky, so let your creativity guide you.