The Pleiades, catalogued as Messier 45, form one of the most photogenic open star clusters in the sky, spanning an angular size of 1.3° (77′) that fits comfortably within a wide-field refractor or telephoto lens frame. Surrounding the brightest member stars lies a delicate web of blue reflection nebulosity, itself catalogued as several separate objects: the Electra Nebula (vdB 20), the Maia Nebula (vdB 21), the Merope Nebula (vdB 22) and the nebula around Alcyone (vdB 23). Although eye and camera perceive them as a single glittering target, astronomers list the cluster and each reflection nebula as independent entries with their own designations and data. Capturing the faint dusty tendrils demands generous exposure time and dark, transparent skies, since the nebulae are far dimmer than the dazzling stars that light them.
Names and Catalog numbers
- Pleiades
- M 45 (Messier 45)
- Electra Nebula (member object: vdB 20)
- vdB 20 (van den Bergh 20) (member object: vdB 20)
- Maia Nebula (member object: vdB 21)
- Mel 22 (Melotte 22) (member object: vdB 21)
- vdB 21 (van den Bergh 21) (member object: vdB 21)
- Merope Nebula (member object: vdB 22)
- vdB 22 (van den Bergh 22) (member object: vdB 22)
- Alcyone (member object: vdB 23)
- vdB 23 (van den Bergh 23) (member object: vdB 23)
Position and the cosmic neighborhood
The Pleiades sit in Taurus at a right ascension of 03h 46m 24.2s and a declination of +24° 06′ 50″, riding high through northern winter nights and making them an ideal early-evening imaging subject. The reflection nebulae scattered among the cluster stars cluster tightly around this same region: the Electra Nebula (vdB 20) glows at magnitude 3.7 and lies about 375 light-years distant, the Maia Nebula (vdB 21) shines at magnitude 3.87 around 344 light-years away, the Merope Nebula (vdB 22) reaches magnitude 4.18 at roughly 344 light-years, and the nebulosity around Alcyone (vdB 23) is the brightest at magnitude 2.87, about 403 light-years off. Framing the full complex is straightforward with a short focal length, since all these components fall within the cluster’s 1.3° (77′) footprint, but resolving the individual named nebulae into their distinct shapes rewards careful processing and steady tracking.
Nice to Know
- The Pleiades measure only about 9 light-years across physically, yet span a generous 1.3° (77′) on the sky, making them a natural fit for wide-field astrophotography.
- What looks like one glowing target is actually several catalogued objects at once: the Messier 45 cluster plus the reflection nebulae vdB 20, vdB 21, vdB 22 and vdB 23.
- The blue reflection nebulae shine by scattering starlight rather than emitting their own, so they reveal their full extent only in long, deep exposures.
- Among the surrounding nebulae, the Alcyone nebula (vdB 23) is the brightest at magnitude 2.87, while the Merope Nebula (vdB 22) is the faintest at magnitude 4.18.
Brightness, distance and size
It lies about 424 light-years from Earth and spans roughly 9 light-years across. On the sky it appears about 1.3° (77′) in size.
