M45 - The Pleiades, or Seven Sisters
| Polish version is here |
The Pleiades, occupying position 45 in the Messier catalog (M45), is arguably the most well-known open star cluster in the night sky. It is located in the constellation Taurus, approximately 444 light-years from Earth.
Several stars within the cluster have individual names linked to the Greek myth of the Pleiades. According to mythology, they were the seven daughters of the Titan Atlas and the Oceanid Pleione, and the sisters of the Hyades (which were also placed in the sky as a separate open cluster). Among the Pleiades, we find Taygeta, Maia, Asterope, Sterope II, Merope, Alcyone, Celaeno, and Electra, as well as their revered parents. The fact that eight Pleiades are listed today instead of seven is due to the historical grouping of Asterope and Sterope II under a single name.
The cluster was also recognized in various cultures and often held significant roles in local beliefs. For this reason, these stars are known by numerous other names, including the Chicks, the Seven Sisters, and even the Masonic Church. In some Eastern Slavic languages, such as Ukrainian (Стожари) and Russian (Стажары), as well as in older Polish literature, they are sometimes referred to as Stozhary (pol. Stożary).
The theme of the Pleiades has also been explored in literature. Alongside other stellar groupings—the Hyades and the Double Cluster in Perseus—they play an important role in Sergey Snegov’s sci-fi cycle People as Gods (Russian: Люди как боги). Additionally, in the works of H.P. Lovecraft and the Cthulhu Mythos, the Pleiades are mentioned in reference to the Great Library, an ancient repository of knowledge said to be located on Celaeno or a planet orbiting it.
Observations
January 12, 2020 – Jaworzno (Poland), garden
urban conditions, high level of light pollution
The Pleiades can be easily located in the night sky by extending the line connecting Bellatrix (Gamma Orionis, γ Ori) and Aldebaran (Alpha Tauri, α Tau) beyond Aldebaran toward the northwest. The best conditions for observing this cluster in Poland occur from October to March, making the beginning of the year—such as in this case—an excellent time.
The shape formed by the brightest stars visible to the naked eye in the cluster may resemble a miniature version of the Big Dipper asterism.
The cluster contains several hundred stars. Most of them are blue giants of spectral type B. Their apparent magnitudes range from 3.0m to 5.9m, and they are relatively young stars, with an estimated age of approximately 100 million years.
September 19, 2020 – Jaworzno (Poland), garden
urban conditions, high level of light pollution
Here they are! The Pleiades have returned to the night sky! The beautiful sisters, along with their parents—the Titaness Pleione and the Titan Atlas, who, as we know from Greek mythology, was tasked with carrying the celestial sphere on his shoulders.
After several months of absence—roughly since late March—the Pleiades are once again visible for increasingly long periods at night, allowing observers to admire this magnificent open cluster without the need for a telescope or any optical aids.
While the Pleiades can easily be seen with the naked eye under dark skies, binoculars provide a significantly enhanced viewing experience. However, much more intricate details become visible only in long-exposure photographs. The presented image was taken rather spontaneously from an area with high levels of light pollution, without a telescope, near the time of the full Moon and in its relatively close proximity.
It was a pleasant surprise to see that even in such a suboptimal photograph, taken under difficult conditions, the delicate outline of the beautiful blue nebula enveloping the stars in this cluster could still be discerned.
December 6, 2021 – Jaworzno (Poland), garden
urban conditions, high level of light pollution
This time, the observing conditions were ideal—the night was moonless, quite cold, and the sky remained clear long enough to collect sufficient data.
Thanks to better conditions and a longer exposure time than in Photo 2, we can now more clearly see the stunning set of reflection nebulae illuminated by the blue glow of young, hot stars. Notable among them is the Merope Nebula (NGC 1435, also known as Tempel’s Nebula) and the nebula surrounding Maia (NGC 1432). These beautiful clouds of gas and dust may be remnants of the molecular cloud from which the cluster's stars formed, although other origins are also possible. The striking bluish hue of these nebulae results from the presence of fine carbonaceous dust scattered throughout this region of space.
Photo 1 Parameters:
- Total exposure time: 10 seconds (single shot)
- Canon EOS 60D
- ISO: 1500
- Lens: zoom type (used at fmax = 250mm)
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Photo 2 Parameters:
- Total exposure time: 15 minutes (stack of 15 RAW frames at 60s each, using an appropriate number of dark, bias, and flat frames)
- Canon EOS 60D
- ISO: 500
- Lens: zoom type (used at fmax = 250mm)
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Photo 3 Parameters:
- Total exposure time: 28 minutes (stack of 14 RAW frames at 120s each, using an appropriate number of dark, bias, and flat frames)
- Canon EOS 60D
- ISO: 1500
- Lens: zoom type (used at fmax = 250mm)
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Marek Ples