The Pleiades M45: Winter's Most Beautiful Star Cluster

You've seen them even if you didn't know their name. A small, tight group of stars, like a tiny, misty dipper, glinting in the winter sky. The Pleiades, also called the Seven Sisters or Messier 45, is one of the most ancient and beloved sights in all of astronomy. Nearly every culture on Earth has a name and a story for this cluster.

And while you can appreciate the Pleiades with nothing more than your eyes, binoculars and telescopes reveal layers of beauty that make M45 one of the most rewarding objects you'll ever observe.

Finding the Pleiades

The Pleiades is easy to find in the constellation Taurus, visible from roughly October through April in the Northern Hemisphere. Here's how to locate it:

1. Find Orion, the most recognizable winter constellation, with its three-star belt.
2. Follow the line of Orion's belt upward and to the right. You'll first hit the bright orange star Aldebaran and the V-shaped Hyades cluster (the head of Taurus the Bull).
3. Continue in the same direction past Aldebaran, and you'll reach the Pleiades, a compact, hazy grouping about the size of your fingertip at arm's length.

The Pleiades is circumpolar from latitudes above about 65°N, but it's best observed when it's high in the sky during autumn and winter evenings. If you're learning the constellations, our star hopping guide will help you navigate from one landmark to the next.

What You'll See

Naked Eye

The Pleiades is one of the best tests of sky darkness and visual acuity. From a dark site, you'll see a compact group of blue-white stars surrounded by a subtle haze. From a city, you might only spot the 3-4 brightest members. Counting Pleiades stars is a tradition that stretches back millennia, ancient navigators used it as a vision test.

Binoculars (The Best View)

Here's a secret that experienced observers know: the single most beautiful view of the Pleiades is through ordinary binoculars. A pair of 7x50 or 10x50 binoculars frames the cluster perfectly, revealing dozens of blue-white stars scattered across the field like diamonds on dark velvet. The view is absolutely stunning and requires no telescope, no setup, no tracking.

Telescope

Through a telescope, the view changes character depending on your magnification:

• Low power (25-40x): The cluster fills the field with brilliant blue-white stars. You might glimpse faint wisps of the reflection nebulosity surrounding the brighter members, especially Merope.
• Medium power (60-100x): The cluster no longer fits in the field, but you can explore individual stars and look for the Merope Nebula (NGC 1435), a faint glow around the star Merope.
• High power: Generally not useful for the Pleiades. This is an object that rewards wide fields and low magnification.

The Science Behind the Beauty

The Pleiades is an open cluster, a group of stars that formed together from the same cloud of gas and dust and are still loosely bound by gravity. Here are the key facts:

The stars of the Pleiades are hot, blue, and luminous, spectral types B and A. Their blue color is intrinsic, not caused by the surrounding nebulosity. These are massive stars that burn through their fuel much faster than our Sun. In about 250 million years, the cluster will have dispersed and the brightest members will have ended their lives.

The Named Stars

The brightest Pleiades stars carry names from Greek mythology, the seven daughters of Atlas and Pleione:

• Alcyone, The brightest member at magnitude 2.87
• Atlas, The father, magnitude 3.63
• Electra, Magnitude 3.70
• Maia, Magnitude 3.87
• Merope, Magnitude 4.18, surrounded by the brightest reflection nebula
• Taygeta, Magnitude 4.30
• Pleione, The mother, magnitude 5.09 (variable)
• Celaeno, Magnitude 5.45
• Asterope, Actually a double star, magnitude 5.8

Learning to identify these individual stars is a lovely exercise in careful observation. Use a detailed star chart or app to match each name to its position in the cluster.

Photographing the Pleiades

The Pleiades is a spectacular astrophotography target, especially when you capture the surrounding reflection nebulosity. Even a DSLR on a star tracker with a telephoto lens (135-200mm) can reveal the blue wisps around the brighter stars with just a few minutes of total exposure.

For detailed capture and processing advice, check our astrophotography beginner's guide and image stacking tutorial.