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Observing Pleiades (M45)
The Pleiades, also known as Seven Sisters and Messier 45 (M45), is an asterism of an open star cluster containing young B-type stars in the northwest of the constellation Taurus. At a distance of about 444 light-years, it is among the star clusters nearest to Earth and is the Messier object nearest to Earth, being the star cluster most obvious to the naked eye in the night sky.
What Pleiades is
The Pleiades, also known as Seven Sisters and Messier 45 (M45), is an asterism of an open star cluster containing young B-type stars in the northwest of the constellation Taurus. At a distance of about 444 light-years, it is among the star clusters nearest to Earth and is the Messier object nearest to Earth, being the star cluster most obvious to the naked eye in the night sky. It contains over 1,000 stars, with the brightest six or seven being easily visible to the naked eye.
How to observe it
This is a naked-eye or binocular object under a dark sky. Any telescope shows it, and a low-power, wide-field eyepiece gives the most pleasing view.
It lies in the constellation Taurus. To find it, learn the constellation first, then star-hop from its brighter stars with a finder or a wide-field eyepiece before switching to more magnification.
Magnification is your telescope's focal length divided by your eyepiece's focal length. For an extended object like this, start low to frame it, then step up in power only if the object takes it. Use the Fit My Telescope tool to see the exact magnification, true field and exit pupil each of your eyepieces gives.
How it looks at the eyepiece
What you see at the eyepiece is fainter and less colourful than a photograph, because the eye takes in light in an instant while a camera builds it up over minutes. Expect a grey glow rather than the vivid colours of an image, and let your eyes dark-adapt for at least twenty minutes to see the most.
This object is the Pleiades, a naked-eye open cluster best in binoculars or a wide field, which makes it a rewarding target once you have found it.
Frame it at low to medium power first with a wide true field, then step up the magnification only if the object stays sharp and the sky is steady. The Fit My Telescope tool shows the magnification, true field of view and exit pupil each of your eyepieces gives in your telescope, so you can pick the one that frames the object best.
The object in NASA imagery
NASA has imaged this object. One example in the NASA Image and Video Library is titled Pink Pleiades, from JPL.
The Seven Sisters, also known as the Pleiades star cluster, seem to float on a bed of feathers in a new infrared image from NASA Spitzer Space Telescope. Clouds of dust sweep around the stars, swaddling them in a cushiony veil.
NASA imagery is in the public domain. What you see through an eyepiece is fainter and mostly grey, since the eye does not accumulate light the way a long-exposure camera does, but knowing an object's true shape helps you recognise it at the telescope.
| Property | Value |
|---|---|
| Object type | open cluster |
| Constellation | Taurus |
| Apparent magnitude | 1.6 |
| Catalogue | Messier 45 (M45) |
Object data from Wikidata (CC0) and standard Messier catalogues.
What magnification suits M45?
Open the Fit My Telescope toolSee the true field and exit pupil each eyepiece givesFind telescope eyepiece on eBayaffiliateRelated
Sources: Pleiades (Wikipedia, CC BY-SA) · Wikidata (CC0) · NASA Image and Video Library: PIA09262 (public domain)