Observe and shoot the Moon as it crosses paths with the Seven Sisters this spring

The early months of the year are great for observing, imaging or simply appreciating the beauty of the waxing crescent Moon. This is because the plane of Earth’s orbit (the ecliptic) makes a steep angle with the western horizon after sunset. The Moon’s orbit is inclined to the ecliptic by 5°, meaning the Moon never wanders too far from the ecliptic’s position in the sky. As a consequence, at this time of the year, the earlier phases of the Moon are presented at their best.

At the same time, the constellation of Taurus, the Bull, is positioned above the western horizon in the early evening sky, which presents us with an opportunity to capture the waxing crescent Moon with that most beautiful of star clusters, the Pleiades or M45.

Also known as the Seven Sisters, the Pleiades sits 4.2˚ north of the ecliptic. This means that it lies within the Moon’s corridor of motion across the sky and, at certain times, it’s possible to see the Moon pass in front of the cluster stars. This is not the case currently, with the Moon appearing to pass below the cluster, but this can be a beautiful scene to capture too. In this article we will show you how to do this.

The months of February, March and April are optimal for a shot of the waxing crescent Moon and the Pleiades. Any earlier and the Moon’s phase will be too great – its glare burning out the cluster’s delicate stars; any later and the Pleiades will be doing battle with the evening twilight and their impact will be lost. There’s a chance to capture both objects on the evenings of 7–9 March, with the smallest separation occurring on 8 March. There’s another chance on 4 and 5 April, when the Moon’s crescent will be thinner and better matched to the cluster.

You can capture the Moon and the Pleiades with different types of camera, but for the best results consider using a device with good manual control, such as a DSLR camera or MILC (mirrorless interchangeable-lens camera).

A good choice of field of view can make or break a photograph like this. As the sky darkens, both objects will get closer to the western horizon. In March there’s a fair amount of time between the sky getting properly dark and the Moon and Pleiades setting, while in April there’s a bit less time. If there’s something interesting in the foreground, consider using it in the shot. For this you’ll need a field of view that can contain both objects and sufficient foreground horizon to prevent the image appearing cramped.

The Pleiades is a deep-sky object that typically requires a multi-second exposure to capture well, while the Moon is a bright, extended Solar System object that will overexpose using longer exposures. This puzzle may seem impossible to solve, but with a bit of creativity you can produce some amazing results. Also, if clouds are present, you could use them to introduce some extra detail into the image.

Equipment: a DSLR camera or MILC (mirrorless interchangeable-lens camera)

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Step by step

STEP 1

Work out the field of view required to capture the Moon and Pleiades when the sky is clear. If you’re planning to incorporate foreground scenery, a larger field is needed. A good maximum to consider is a long axis coverage of around 28°, using a 40mm lens on a non-full frame camera or 65mm for full frame.

STEP 2

You’ll need a dark sky to get the best results, which means photographing after 20:00 UT in March or 22:00 BST (21:00 UT) in April. Pick a location with no high foreground objects that might hide the Moon or Pleiades. You’ll have more time to gauge what’s happening in March (the two objects set earlier in April).

STEP 3

If you don’t have a MILC or DSLR camera, you may be able to capture the scene with a smartphone, depending on its sensitivity to low light conditions. By all means use your phone camera’s zoom function, but if it has optical and digital zoom, you’re better off using the optical zoom to maintain quality.

STEP 4

Frame your shot and focus on the Moon. Set a low to mid ISO, say 1,600-3,200, then fully open the lens and increase the f/-number by a stop or two to prevent edge distortion. For a fixed tripod, use up to a maximum exposure (in seconds) of 500 divided by the focal length of your lens (in millimetres).

STEP 5

With a tracking mount you can increase the maximum exposure, but be careful not to over expose the Moon. A tracking mount also lets you to stop the lens down further, increasing exposure time to compensate. Using say, f/11, the aperture blades of the lens should create diffraction spikes from the bright Moon.

STEP 6

If patchy clouds interfere, use these to good effect. If the cloud is broken and thin, it may even be possible to time your shot so the Pleiades is seen under clear sky while the Moon is reduced in brightness by cloud. This can allow you to really bring out detail in the cluster without the Moon dominating the shot.

Send your images to: gallery@skyatnightmagazine.com

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ALL PICTURES: PETE LAWRENCE