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70-451: The Matariki Network of Universities ( MNU ) is an international group of universities that focuses on strong links between research and undergraduate teaching. Each member is leading international best practice in research and education based on long academic traditions. The MNU was established in 2010 to enable universities to enhance diversity, to share ideas and expertise, and to learn international best practice from each other, recognising

140-411: A Hertzsprung–Russell diagram for the cluster, which, when compared with those plotted for clusters whose distance is not known, allows their distances to be estimated. Other methods may then extend the distance scale from open clusters to galaxies and clusters of galaxies, and a cosmic distance ladder may be constructed. Ultimately astronomers' understanding of the age and future evolution of the universe

210-401: A bow and a quiver. As noted by scholar Stith Thompson , the constellation was "nearly always imagined" as a group of seven sisters, and their myths explain why there are only six. Some scientists suggest that these may come from observations back when Pleione was farther from Atlas and more visible as a separate star as far back as 100,000 BC. In Japan , the cluster is mentioned under

280-604: A distinct constellation , and they are mentioned by Hesiod 's Works and Days , Homer 's Iliad and Odyssey , and the Geoponica . The Pleiades was the most well-known "star" among pre-Islamic Arabs and so often referred to simply as "the Star" ( an-Najm ; النجم ). Some scholars of Islam suggested that the Pleiades are the "star" mentioned in Surah An-Najm ("The Star") in

350-541: A few days around the equinox when the Sun goes directly behind the satellite relative to Earth (i.e. within the beam-width of the ground-station antenna) for a short period each day. The Sun's immense power and broad radiation spectrum overload the Earth station's reception circuits with noise and, depending on antenna size and other factors, temporarily disrupt or degrade the circuit. The duration of those effects varies but can range from

420-400: A few days towards the winter side of each equinox. One result of this is that, at latitudes below ±2.0 degrees, all the days of the year are longer than the nights. The times of sunset and sunrise vary with the observer's location ( longitude and latitude ), so the dates when day and night are equal also depend upon the observer's location. A third correction for the visual observation of

490-403: A few minutes to an hour. (For a given frequency band, a larger antenna has a narrower beam-width and hence experiences shorter duration "Sun outage" windows.) Satellites in geostationary orbit also experience difficulties maintaining power during the equinox because they have to travel through Earth's shadow and rely only on battery power. Usually, a satellite travels either north or south of

560-402: A map of 64 stars of the Pleiades from his observations in 1779, which he published in 1786. The distance to the Pleiades can be used as a key first step to calibrate the cosmic distance ladder . As the cluster is relatively close to the Earth, the distance should be relatively easy to measure and has been estimated by many methods. Accurate knowledge of the distance allows astronomers to plot

630-437: A mountain peak turning gold in the sunlight long before the lower slopes are illuminated. The date on which the day and night are exactly the same is known as an equilux ; the neologism , believed to have been coined in the 1980s, achieved more widespread recognition in the 21st century. At the most precise measurements, a true equilux is rare, because the lengths of day and night change more rapidly than any other time of

700-441: A mythical mother, Pleione , effectively meaning "daughters of Pleione". In reality, the ancient name of the star cluster related to sailing almost certainly came first in the culture, naming of a relationship to the sister deities followed, and eventually appearing in later myths, to interpret the group name, a mother, Pleione. The M45 group played an important role in ancient times for the establishment of many calendars thanks to

770-416: A sunrise (or sunset) is the angle between the apparent horizon as seen by an observer and the geometric (or sensible) horizon. This is known as the dip of the horizon and varies from 3 arcminutes for a viewer standing on the sea shore to 160 arcminutes for a mountaineer on Everest. The effect of a larger dip on taller objects (reaching over 2½° of arc on Everest) accounts for the phenomenon of snow on

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840-460: Is 50 arcminutes below the geometric horizon, which is the intersection with the celestial sphere of a horizontal plane through the eye of the observer. These effects make the day about 14 minutes longer than the night at the equator and longer still towards the poles. The real equality of day and night only happens in places far enough from the equator to have a seasonal difference in day length of at least 7 minutes, actually occurring

910-536: Is a result of uncertainties in stellar evolution models, which include factors such as convective overshoot , in which a convective zone within a star penetrates an otherwise non-convective zone, resulting in higher apparent ages. Another way of estimating the age of the cluster is by looking at the lowest-mass objects. In normal main-sequence stars, lithium is rapidly destroyed in nuclear fusion reactions. Brown dwarfs can retain their lithium, however. Due to lithium's very low ignition temperature of 2.5 × 10 K,

980-592: Is also evident in northern Europe. The Pleiades cluster is displayed on the Nebra sky disc that was found in Germany and is dated to around 1600 BC. On the disk the cluster is represented in a high position between the Sun and the Moon. This asterism also marks the beginning of several ancient calendars: Although M45 is no longer at the vernal point, the asterism still remains important, both functionally and symbolically. In addition to

1050-458: Is dominated by fainter and redder stars . An estimate of the frequency of binary stars in the Pleiades is approximately 57%. The cluster contains many brown dwarfs , such as Teide 1 . These are objects with less than approximately 8% of the Sun 's mass, insufficient for nuclear fusion reactions to start in their cores and become proper stars. They may constitute up to 25% of the total population of

1120-503: Is influenced by their knowledge of the distance to the Pleiades. Yet some authors argue that the controversy over the distance to the Pleiades discussed below is a red herring , since the cosmic distance ladder can (presently) rely on a suite of other nearby clusters where consensus exists regarding the distances as established by the Hipparcos satellite and independent means (e.g., the Hyades ,

1190-883: The Arabs (who call them al-Thurayyā ; الثريا ); the Chinese (who called them mǎo ; 昴 ); the Quechua (who call them Qullqa or the storehouse); the Japanese (who call them Subaru ; 昴 , スバル ); the Maya ; the Aztec ; the Sioux ; the Kiowa ; and the Cherokee . In Hinduism , the Pleiades are known as Kṛttikā and are scripturally associated with the war deity Kartikeya and are also identified or associated with

1260-520: The Coma Berenices cluster , etc.). Measurements of the distance have elicited much controversy. Results prior to the launch of the Hipparcos satellite generally found that the Pleiades were approximately 135 parsecs (pc) away from Earth. Data from Hipparcos yielded a surprising result, namely a distance of only 118 pc, by measuring the parallax of stars in the cluster—a technique that should yield

1330-466: The Hyades were sisters of the Pleiades. The following table gives details of the brightest stars in the cluster: Ages for star clusters may be estimated by comparing the Hertzsprung–Russell diagram for the cluster with theoretical models of stellar evolution . Using this technique, ages for the Pleiades of between 75 and 150 million years have been estimated. The wide spread in estimated ages

1400-542: The March equinox , indicating that at that moment the solar declination is crossing the celestial equator in a northward direction, and southward equinox for the September equinox , indicating that at that moment the solar declination is crossing the celestial equator in a southward direction. Daytime is increasing at the fastest at the vernal equinox and decreasing at the fastest at the autumnal equinox. Systematically observing

1470-508: The Quran . On numerous cylinder seals from the beginning of the first millennium BC, M45 is represented by seven points, while the Seven Gods appear, on low-reliefs of Neo-Assyrian royal palaces, wearing long open robes and large cylindrical headdresses surmounted by short feathers and adorned with three frontal rows of horns and a crown of feathers, while carrying both an ax and a knife, as well as

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1540-519: The Saptamatrika(s) (Seven Mothers). Hindus celebrate the first day (new moon) of the month of Kartik as Diwali , a festival of abundance and lamps. The Pleiades are also mentioned three times in the Bible . The earliest known depiction of the Pleiades is likely a Northern German Bronze Age artifact known as the Nebra sky disk , dated to approximately 1600 BC. The Babylonian star catalogues name

1610-479: The Spitzer Space Telescope and Gemini North telescope , astronomers discovered that one of the stars in the cluster, HD 23514 , which has a mass and luminosity a bit greater than that of the Sun, is surrounded by an extraordinary number of hot dust particles. This could be evidence for planet formation around HD 23514. Equinox A solar equinox is a moment in time when the Sun crosses

1680-497: The Sun 's disk. Equivalently, this is the moment when Earth's rotation axis is directly perpendicular to the Sun-Earth line, tilting neither toward nor away from the Sun. In modern times , since the Moon (and to a lesser extent the planets) causes Earth's orbit to vary slightly from a perfect ellipse , the equinox is officially defined by the Sun's more regular ecliptic longitude rather than by its declination . The instants of

1750-519: The atmospheric refraction is assumed to be 34 arcminutes, and the assumed semidiameter (apparent radius ) of the Sun is 16  arcminutes . (The apparent radius varies slightly depending on time of year, slightly larger at perihelion in January than aphelion in July , but the difference is comparatively small.) Their combination means that when the upper limb of the Sun is on the visible horizon, its centre

1820-497: The date of Easter , which means he wanted to move the vernal equinox to the date on which it fell at that time (21 March is the day allocated to it in the Easter table of the Julian calendar), and to maintain it at around that date in the future, which he achieved by reducing the number of leap years from 100 to 97 every 400 years. However, there remained a small residual variation in

1890-504: The proper motions of the stars, it was found that they are all moving in the same direction across the sky, at the same rate, further demonstrating that they were related. Charles Messier measured the position of the cluster and included it as "M45" in his catalogue of comet -like objects, published in 1771. Along with the Orion Nebula and the Praesepe cluster, Messier's inclusion of

1960-435: The sunrise , people discovered that it occurs between two extreme locations at the horizon and eventually noted the midpoint between the two. Later it was realized that this happens on a day when the duration of the day and the night are practically equal and the word "equinox" comes from Latin aequus , meaning "equal", and nox , meaning "night". In the northern hemisphere, the vernal equinox (March) conventionally marks

2030-763: The weighted mean ; they gave a Hipparcos parallax distance of 126 pc and photometric distance of 132 pc based on stars in the AB Doradus , Tucana-Horologium and Beta Pictoris moving groups, which are all similar in age and composition to the Pleiades. Those authors note that the difference between these results may be attributed to random error. More recent results using very-long-baseline interferometry (VLBI) (August 2014), and preliminary solutions using Gaia Data Release 1 (September 2016) and Gaia Data Release 2 (August 2018), determine distances of 136.2 ± 1.2 pc, 134 ± 6 pc and 136.2 ± 5.0 pc, respectively. The Gaia Data Release 1 team were cautious about their result, and

2100-676: The Blue Economy" theme brought together researchers from the Matariki universities to identify ways in which the marine economy could achieve economic goals while also building environmental resilience. The network was set up by seven universities in 2010. These were joined by an eighth university, University of the Western Cape in South Africa, in 2024. Pleiades The cluster is dominated by hot blue luminous stars that have formed within

2170-415: The Earth's equator , which is to say, appears directly above the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and set "due west". This occurs twice each year, around 20 March and 23 September . More precisely, an equinox is traditionally defined as the time when the plane of Earth 's equator passes through the geometric center of

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2240-474: The Earth's shadow because Earth's axis is not directly perpendicular to a line from the Earth to the Sun at other times. During the equinox, since geostationary satellites are situated above the Equator, they are in Earth's shadow for the longest duration all year. Equinoxes are defined on any planet with a tilted rotational axis. A dramatic example is Saturn, where the equinox places its ring system edge-on facing

2310-594: The Ecliptic . The name, Pleiades, comes from Ancient Greek : Πλειάδες . It probably derives from plein ("to sail") because of the cluster's importance in delimiting the sailing season in the Mediterranean Sea : "the season of navigation began with their heliacal rising ". In Classical Greek mythology the name was used for seven divine sisters called the Pleiades . In time, the name was said to be derived from that of

2380-672: The Moon , i.e. five times the path that the "Moon" travels on average in one day and one night, to use the terminology of Abd al-Rahman al-Sufi . In Turkic Mythology - The Pleiades Constellation is one of the oldest cosmological figures of the Turks. Seasonal cycles in Anatolia are determined by this star group. The Pleiades are a prominent sight in winter in the Northern Hemisphere , and are easily visible from mid-southern latitudes. They have been known since antiquity to cultures all around

2450-521: The North Pole is 18 March 07:09 UTC, and sunset on the South Pole is 22 March 13:08 UTC. Also in 2021, sunrise on the South Pole is 20 September 16:08 UTC, and sunset on the North Pole is 24 September 22:30 UTC. In other words, the equinoxes are the only times when the subsolar point is on the equator, meaning that the Sun is exactly overhead at a point on the equatorial line. The subsolar point crosses

2520-554: The Pleiades MUL ( 𒀯𒀯 ), meaning "stars" (literally "star star"), and they head the list of stars along the ecliptic, reflecting the fact that they were close to the point of the vernal equinox around the twenty-third century BC. The Ancient Egyptians may have used the names "Followers" and "Ennead" in the prognosis texts of the Calendar of Lucky and Unlucky Days of papyrus Cairo 86637. Some Greek astronomers considered them to be

2590-461: The Pleiades has been noted as curious, as most of Messier's objects were much fainter and more easily confused with comets—something that seems scarcely possible for the Pleiades. One possibility is that Messier simply wanted to have a larger catalogue than his scientific rival Lacaille , whose 1755 catalogue contained 42 objects, and so he added some bright, well-known objects to boost the number on his list. Edme-Sébastien Jeaurat then drew in 1782

2660-499: The Pleiades showing 36 stars, in his treatise Sidereus Nuncius in March 1610. The Pleiades have long been known to be a physically related group of stars rather than any chance alignment. John Michell calculated in 1767 that the probability of a chance alignment of so many bright stars was only 1 in 500,000, and so surmised that the Pleiades and many other clusters must consist of physically related stars. When studies were first made of

2730-452: The Pleiades were probably formed from a compact configuration that once resembled the Orion Nebula . Astronomers estimate that the cluster will survive for approximately another 250 million years, after which the clustering will be lost due to gravitational interactions with the galactic neighborhood. Together with the open star cluster of the Hyades , the Pleiades form the Golden Gate of

2800-421: The Sun, atmospheric refraction , and the rapidly changing duration of the length of day that occurs at most latitudes around the equinoxes. Long before conceiving this equality, equatorial cultures noted the day when the Sun rises due east and sets due west , and indeed this happens on the day closest to the astronomically defined event. As a consequence, according to a properly constructed and aligned sundial ,

2870-450: The Sun. As a result, they are visible only as a thin line when seen from Earth. When seen from above – a view seen during an equinox for the first time from the Cassini space probe in 2009 – they receive very little sunshine ; indeed, they receive more planetshine than light from the Sun. This phenomenon occurs once every 14.7 years on average, and can last a few weeks before and after

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2940-403: The Sun. It is only after a complete Gregorian leap-year cycle of 400 years that the seasons commence at approximately the same time. In the 21st century the earliest March equinox will be 19 March 2096, while the latest was 21 March 2003. The earliest September equinox will be 21 September 2096 while the latest was 23 September 2003 ( Universal Time ). On the date of

3010-533: The VLBI authors assert "that the Hipparcos -measured distance to the Pleiades cluster is in error". The most recent distance estimate of the distance to the Pleiades based on the Gaia Data Release 3 is 135.74 ± 0.10 pc . The cluster core radius is approximately 8 light-years and tidal radius is approximately 43 light-years. The cluster contains more than 1,000 statistically confirmed members, not counting

3080-595: The beginning of spring in most cultures and is considered the start of the New Year in the Assyrian calendar , Hindu, and the Persian or Iranian calendars , while the autumnal equinox (September) marks the beginning of autumn. Ancient Greek calendars too had the beginning of the year either at the autumnal or vernal equinox and some at solstices. The Antikythera mechanism predicts the equinoxes and solstices. The equinoxes are

3150-448: The calendar "drifted" with respect to the two equinoxes – so that in 300 AD the spring equinox occurred on about 21 March, and by the 1580s AD it had drifted backwards to 11 March. This drift induced Pope Gregory XIII to establish the modern Gregorian calendar . The Pope wanted to continue to conform with the edicts of the Council of Nicaea in 325 AD concerning

3220-519: The changes in the calendars based on the lunar stations among the Indians and the Arabs, consider the case of an ancient Yemeni calendar in which the months are designated according to an astronomical criterion that caused it to be named Calendar of the Pleiades : the month of ḫams , literally "five", is that during which the Sun and al-Ṯurayyā , i.e. the Pleiades , deviate from each other by five movements of

3290-431: The cluster is simply passing through a particularly dusty region of the interstellar medium . Studies show that the dust responsible for the nebulosity is not uniformly distributed, but is concentrated mainly in two layers along the line of sight to the cluster. These layers may have been formed by deceleration due to radiation pressure as the dust has moved toward the stars. Analyzing deep-infrared images obtained by

3360-458: The cluster may be seen even with small telescopes or average binoculars. It is a reflection nebula , caused by dust reflecting the blue light of the hot, young stars. It was formerly thought that the dust was left over from the formation of the cluster, but at the age of approximately 100 million years generally accepted for the cluster, almost all the dust originally present would have been dispersed by radiation pressure . Instead, it seems that

3430-405: The cluster will take approximately 250 million years to disperse, because of gravitational interactions with giant molecular clouds and the spiral arms of our galaxy hastening its demise. With larger amateur telescopes, the nebulosity around some of the stars may be easily seen, especially when long-exposure photographs are taken. Under ideal observing conditions, some hint of nebulosity around

3500-633: The cluster, although they contribute less than 2% of the total mass. Astronomers have made great efforts to find and analyze brown dwarfs in the Pleiades and other young clusters, because they are still relatively bright and observable, while brown dwarfs in older clusters have faded and are much more difficult to study. The brightest stars of the cluster are named the Seven Sisters in early Greek mythology : Sterope , Merope , Electra , Maia , Taygeta , Celaeno , and Alcyone . Later, they were assigned parents, Pleione and Atlas . As daughters of Atlas,

3570-483: The combination of two remarkable elements. The first, which is still valid, is its unique and easily identifiable appearance on the celestial vault near the ecliptic . The second, essential for the ancients, is that in the middle of the third millennium BC, this asterism (a prominent pattern or group of stars that is smaller than a constellation) marked the vernal point . (2330 BC with ecliptic latitude about +3.5° according to Stellarium ) The importance of this asterism

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3640-457: The date and time of the vernal equinox of about ±27 hours from its mean position, virtually all because the distribution of 24 hour centurial leap-days causes large jumps (see Gregorian calendar leap solstice ). The dates of the equinoxes change progressively during the leap-year cycle, because the Gregorian calendar year is not commensurate with the period of the Earth's revolution about

3710-497: The daytime duration is 12 hours. In the Northern Hemisphere , the March equinox is called the vernal or spring equinox while the September equinox is called the autumnal or fall equinox. In the Southern Hemisphere , the reverse is true. During the year, equinoxes alternate with solstices . Leap years and other factors cause the dates of both events to vary slightly. Hemisphere-neutral names are northward equinox for

3780-533: The equator moving northward at the March equinox and southward at the September equinox. When Julius Caesar established the Julian calendar in 45 BC, he set 25 March as the date of the spring equinox; this was already the starting day of the year in the Persian and Indian calendars. Because the Julian year is longer than the tropical year by about 11.3 minutes on average (or 1 day in 128 years),

3850-428: The equinox, the center of the Sun spends a roughly equal amount of time above and below the horizon at every location on the Earth, so night and day are about the same length. Sunrise and sunset can be defined in several ways, but a widespread definition is the time that the top limb of the Sun is level with the horizon. With this definition, the day is longer than the night at the equinoxes: In sunrise/sunset tables,

3920-556: The equinox; the Angkor Wat Equinox during which the sun rises in a perfect alignment over Angkor Wat in Cambodia is one such example. Catholic churches , since the recommendations of Charles Borromeo , have often chosen the equinox as their reference point for the orientation of churches . One effect of equinoctial periods is the temporary disruption of communications satellites . For all geostationary satellites, there are

3990-461: The equinoxes are currently defined to be when the apparent geocentric longitude of the Sun is 0° and 180°. The word is derived from the Latin aequinoctium , from aequus (equal) and nox (night). On the day of an equinox, daytime and nighttime are of approximately equal duration all over the planet. Contrary to popular belief, they are not exactly equal because of the angular size of

4060-466: The equinoxes. The equinoxes are sometimes regarded as the start of spring and autumn. A number of traditional harvest festivals are celebrated on the date of the equinoxes. People in countries including Iran, Afghanistan, Tajikistan celebrate Nowruz which is spring equinox in northern hemisphere. This day marks the new year in Solar Hijri calendar . Religious architecture is often determined by

4130-613: The highest-mass brown dwarfs will burn it eventually, and so determining the highest mass of brown dwarfs still containing lithium in the cluster may give an idea of its age. Applying this technique to the Pleiades gives an age of about 115 million years. The cluster is slowly moving in the direction of the feet of what is currently the constellation of Orion . Like most open clusters, the Pleiades will not stay gravitationally bound forever. Some component stars will be ejected after close encounters with other stars; others will be stripped by tidal gravitational fields. Calculations suggest that

4200-535: The inner pair of stars within Atlas (a bright triple star in the Pleiades) favors a distance of 133 to 137 pc. However, the author of the 2007–2009 catalog of revised Hipparcos parallaxes reasserted that the distance to the Pleiades is ~120 pc and challenged the dissenting evidence. In 2012, Francis and Anderson proposed that a systematic effect on Hipparcos parallax errors for stars in clusters would bias calculation using

4270-602: The international element had been less effective, in particular due to differences in time zones and in academic calendars. The academic libraries of the member institutions have collaborated on benchmarking activities to set their performance in an international context and to develop and share best practices. The libraries also collaborated on assessing whether 'flipped subscription' models for open access publishing , where funds previously used for journal subscriptions are flipped to instead pay article publishing costs, were viable for mid-sized research universities. The "Oceans and

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4340-437: The last 100 million years. Reflection nebulae around the brightest stars were once thought to be leftover material from their formation, but are now considered likely to be an unrelated dust cloud in the interstellar medium through which the stars are currently passing. This dust cloud is estimated to be moving at a speed of approximately 18 km/s relative to the stars in the cluster. Computer simulations have shown that

4410-490: The most direct and accurate results. Later work consistently argued that the Hipparcos distance measurement for the Pleiades was erroneous: In particular, distances derived to the cluster via the Hubble Space Telescope and infrared color–magnitude diagram fitting (so-called " spectroscopic parallax ") favor a distance between 135 and 140 pc; a dynamical distance from optical interferometric observations of

4480-705: The name Mutsuraboshi ("six stars") in the eighth-century Kojiki . The cluster is now known in Japan as Subaru. The name was chosen for that of the Subaru Telescope , the 8.2-meter (320 in) flagship telescope of the National Astronomical Observatory of Japan , located at the Mauna Kea Observatory on the island of Hawaii . It had the largest monolithic primary mirror in the world from its commissioning in 1998 until 2005. It also

4550-436: The number that would be added if all binary stars could be resolved. Its light is dominated by young, hot blue stars , up to 14 of which may be seen with the naked eye, depending on local observing conditions and visual acuity of the observer. The brightest stars form a shape somewhat similar to that of Ursa Major and Ursa Minor . The total mass contained in the cluster is estimated to be approximately 800 solar masses and

4620-455: The only times when the solar terminator (the "edge" between night and day) is perpendicular to the equator. As a result, the northern and southern hemispheres are equally illuminated. For the same reason, this is also the time when the Sun rises for an observer at one of Earth's rotational poles and sets at the other. For a brief period lasting approximately four days, both North and South Poles are in daylight. For example, in 2021 sunrise on

4690-565: The shared commitment to an ethos of excellence in research, scholarship and rounded education. Matariki is the name in the Māori language for the Pleiades star cluster, also known as the Seven Sisters . It reflects the seven founding member universities of the MNU. The Matariki Undergraduate Research Network (MURN) ran in 2012 and 2013 as an attempt to foster international undergraduate research. Assessment of MURN found that it had worked well locally but

4760-653: The world, including the Celts ( Welsh : Tŵr Tewdws , Irish : Streoillín ); pre-colonial Filipinos (who called it Mapúlon , Mulo‑pulo or Muró‑púro , among other names), for whom it indicated the beginning of the year; Hawaiians (who call them Makaliʻi ), Māori (who call them Matariki ); Indigenous Australians (from several traditions ); the Achaemenid Empire , whence in Persians (who called them Parvīn – پروین – or Parvī – پروی );

4830-482: The year around the equinoxes. In the mid-latitudes, daylight increases or decreases by about three minutes per day at the equinoxes, and thus adjacent days and nights only reach within one minute of each other. The date of the closest approximation of the equilux varies slightly by latitude; in the mid-latitudes, it occurs a few days before the spring equinox and after the fall equinox in each respective hemisphere. Mirror-image conjugate auroras have been observed during

4900-410: Was chosen as the brand name of Subaru automobiles to reflect the origins of the firm as the joining of five companies, and is depicted in the firm's six-star logo. Galileo Galilei was the first astronomer to view the Pleiades through a telescope . He thereby discovered that the cluster contains many stars too dim to be seen with the naked eye. He published his observations, including a sketch of

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