This makes the Milky Way difficult to see from brightly lit urban or suburban areas, but very prominent when viewed from rural areas when the Moon is below the horizon. Maps of artificial night sky brightness show that more than one-third of Earth's population cannot see the Milky Way from their homes due to light pollution. As viewed from Earth, the visible region of the Milky Way's galactic plane occupies an area of the sky that includes 30 constellations. The Galactic Center lies in the direction of Sagittarius, where the Milky Way is brightest. From Sagittarius, the hazy band of white light appears to pass around to the galactic anticenter in Auriga.
Appearance
Milky Way
Milky Way | Appearance
The Milky Way is visible from Earth as a hazy band of white light, some 30° wide, arching across the night sky.  As viewed from Earth, the visible region of the Milky Way's galactic plane occupies an area of the sky that includes 30 constellations. Yes. It can be seen as a hazy band of light in the night sky. As viewed from Earth, the visible region of the Milky Way's galactic plane occupies an area of the sky that includes 30 constellations.
where is the solar system located in our galaxy
user
The Solar System, is located in the Milky Way's galactic habitable zone.
assistant
what is the milky way?
user
It is the galaxy that contains our Solar System.
assistant
can you tell me the names of the stars that form a part of this galaxy?
user
The Milky Way may contain ten billion white dwarfs, a billion neutron stars, and a hundred million stellar black holes.
assistant
can this galaxy be seen from earth in the northern hemisphere?
user
M64 (NGC 4826) is known as the Black Eye Galaxy because of the prominent dark dust lane in front of the galaxy's bright nucleus. Also known as the Sleeping Beauty and Evil Eye galaxy, it is about 24 million light-years away. Recent studies indicate that the interstellar gas in the galaxy's outer regions rotates in the opposite direction from that in the inner regions, leading astronomers to believe that at least one satellite galaxy collided with it less than a billion years ago. All other evidence of the smaller galaxy has been assimilated. At the interface between the clockwise- and counterclockwise-rotating regions are many new nebulae and young stars.
Coma Berenices | Other galaxies
The Milky Way is visible from Earth as a hazy band of white light, some 30° wide, arching across the night sky. In night sky observing, although all the individual naked-eye stars in the entire sky are part of the Milky Way Galaxy, the term "Milky Way" is limited to this band of light. The light originates from the accumulation of unresolved stars and other material located in the direction of the galactic plane. Brighter regions around the band appear as soft visual patches known as star clouds. The most conspicuous of these is the Large Sagittarius Star Cloud, a portion of the central bulge of the galaxy.
Milky Way | Appearance
This makes the Milky Way difficult to see from brightly lit urban or suburban areas, but very prominent when viewed from rural areas when the Moon is below the horizon. Maps of artificial night sky brightness show that more than one-third of Earth's population cannot see the Milky Way from their homes due to light pollution. As viewed from Earth, the visible region of the Milky Way's galactic plane occupies an area of the sky that includes 30 constellations. The Galactic Center lies in the direction of Sagittarius, where the Milky Way is brightest. From Sagittarius, the hazy band of white light appears to pass around to the galactic anticenter in Auriga.
Milky Way | Appearance
The fact that the stars visible from the north and south poles do not overlap must mean that the two observation spots are on opposite sides of the Earth, which is not possible if the Earth is a single-sided disc, but is possible for other shapes (like a sphere, but also any other convex shape like a donut or dumbbell). The North Pole is in continuous night for six months of the year. The same hemisphere of stars (a 180° view) are always visible while it is dark, making one counterclockwise rotation every 24 hours. The star Polaris (the "North Star") is almost directly overhead and therefore at the center of this rotation.
Spherical Earth | Observation of constellations on North and South hemispheres at different seasons
NGC 891 looks as the Milky Way would look like when viewed edge-on (some astronomers have even noted how similar to NGC 891 our galaxy looks as seen from the Southern Hemisphere) and, in fact, both galaxies are considered very similar in terms of luminosity and size; studies of the dynamics of its molecular hydrogen have also proven the likely presence of a central bar. Despite this, recent high-resolution images of its dusty disk show unusual filamentary patterns. These patterns are extending into the halo of the galaxy, away from its galactic disk. Scientists presume that supernova explosions caused this interstellar dust to be thrown out of the galactic disk toward the halo.
NGC 891 | Properties
Data obtained in optical light with the Magellan I and II telescopes in Las Campanas, Chile, also provides intriguing information about this object, which is found in the elliptical galaxy NGC 1399 in the Fornax galaxy cluster. The spectrum reveals emission from oxygen and nitrogen but no hydrogen, a rare set of signals from within globular clusters. The physical conditions deduced from the spectra suggest that the gas is orbiting a black hole of at least 1,000 solar masses. To explain these observations, researchers suggest that a white dwarf star strayed too close to an intermediate-mass black hole and was ripped apart by tidal forces.
American Astronomical Society 215th meeting | A possible candidate
The northern celestial hemisphere, also called the Northern Sky, is the northern half of the celestial sphere; that is, it lies north of the celestial equator. This arbitrary sphere appears to rotate westward around a polar axis due to Earth's rotation. At any given time, the entire Northern Sky is visible from the geographic North Pole, while less of this hemisphere is visible the further south the observer is located. The southern counterpart is the southern celestial hemisphere.
Northern celestial hemisphere | Introduction
NGC 676 is a lenticular Seyfert 2 Galaxy about 18.7 Mly away in the constellation Pisces. It can be seen near the star α Piscium. Located close to the celestial equator, it is visible from both hemispheres. BD +04 0244, a star with a visual magnitude of 10.44, is superposed 5.1 arc seconds south-southwest of the nucleus. It is one of the 621 galaxies described in Marat Arakelian’s catalog of high-surface-brightness galaxies.
NGC 676 | Introduction
There is a dust lane along the north-south axis of the galaxy and a disk of dust around the nucleus. Two prominent jets emanating from the nucleus can be observed in the radio band. It has an active galactic nucleus with a supermassive black hole at the core with a mass of . The galaxy is estimated to be about 60 thousand light-years across, and a jet emanating from it is estimated to span about 88 thousand light-years.
NGC 4261 | Introduction
Located within the constellation Canes Venatici, M51 is found by following the easternmost star of the Big Dipper, Eta Ursae Majoris, and going 3.5° southwest. Its declination is +47°, making it a circumpolar for observers located above 43°N latitude; it reaches high altitudes throughout the northern hemisphere making it an accessible object from the early hours in winter through the end of spring season, after which observation is hindered in lower latitudes. M51 is visible through binoculars under dark sky conditions, and it can be resolved in detail with modern amateur telescopes. When seen through a 100 mm telescope the basic outlines of M51 (limited to 5×6') and its companion are visible.
Whirlpool Galaxy | Visual appearance
Discovered by William Herschel on 9 September 1798, this well-studied galaxy has a diameter of approximately 40,000 light-years , about one-third of the Milky Way's size, and it contains roughly half the number of stars as the Milky Way. It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way, with a dimming of ~1.5 magnitudes. Due to its prodigious star formation it has been classified as an active starburst galaxy. Various unusual celestial objects have been observed within NGC 6964. This includes the so-called 'Red Ellipse' along one of the northern arms that looks like a super-bubble or very large supernova remnant, and which may have been formed by an open cluster containing massive stars.
NGC 6946 | Introduction
The galaxy is being viewed nearly edge-on, with an inclination of 18° to the line of sight from the Earth. It is moving away from us with a radial velocity of . The estimated visual luminosity of the galaxy is L, or 42 billion times the brightness of the Sun. Photographs show a tightly wound spiral pattern in the galactic disk, with three dust lanes—the southern side of the galaxy appears dimmer due to the dust configuration. The mass of the free gas and dust in the galaxy is about M and M, respectively, with around M of the gas being in an ionized state.
NGC 4036 | Introduction
The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The galactic center is an intense radio source known as Sagittarius A*, a supermassive black hole of 4.100 (± 0.034) million solar masses. Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much (about 90%) of the mass of the Milky Way is invisible to telescopes, neither emitting nor absorbing electromagnetic radiation. This conjectural mass has been termed "dark matter".
Milky Way | Introduction
The galaxy appears very dim in the sky as it only has an apparent visual magnitude of 13.3 and thus can only be observed with telescopes. It can be classified as type S0 using the Hubble Sequence. The object's distance of roughly 95.6 million light-years from the Solar System can be estimated using its redshift and Hubble's law.
NGC 525 | Description
The star is in the northern celestial hemisphere, but close to the celestial equator; this means that it can be observed from all the inhabited regions of the Earth without difficulty and that it is not visible only in the innermost areas of Antarctica. It appears as circumpolar only far beyond the Arctic polar circle. Its brightness puts it at the limit of visibility to the naked eye, so to be observed without the aid of devices requires a clear, and preferably moonless, sky. The best period for observation in the evening sky is between late October and April from both hemispheres; in February (as at J2000) it is anti-posed from the sun.
HD 34989 | Observation
The "Hubble" Space Telescope imaging analysis showed that this "S" shape structure is indeed two dense low-ionization regions: one moving toward the north-east and another one moving toward the south-west of the nebula, which could be a result of a recent outburst from the central star. Observations with the Southern African Large Telescope have finally found a white dwarf companion in a 4.04 day orbit around the rare low-mass Wolf-Rayet type central star of NGC 5189. NGC 5189 is estimated to be 546 parsecs or 1,780 light years away from Earth. Other measurements have yielded results up to 900 parsecs (~3000 light-years)
NGC 5189 | Introduction
The galaxy now bears his name. The galaxy and southern end of Dorado are in the current epoch at opposition on about 5 December when thus visible from sunset to sunrise from equatorial points such as Ecuador, the Congos, Uganda, Kenya and Indonesia and for part of the night in nearby months. Below about 28° south the galaxy is always sufficiently above the horizon to be considered properly circumpolar, thus spring and autumn also are seasons of much-of-night visibility, and the height of winter in June nearly coincides with closest proximity to the Sun's apparent position.
Large Magellanic Cloud | History of observation
Messier 81 and Messier 82 can both be viewed easily using binoculars and small telescopes. The two objects are generally not observable to the unaided eye, although highly experienced amateur astronomers may be able to see Messier 81 under exceptional observing conditions with a very dark sky. Telescopes with apertures of or larger are needed to distinguish structures in the galaxy. Its far northern declination makes it generally visible for observers in the northern hemisphere. It is not visible to most observers in the southern hemisphere, except those in a narrow latitude range immediately south of the equator.
Messier 81 | Visibility
4 billion solar masses) than the black hole at our Milky Way's center, one of the largest known. The physics that creates the jets is poorly understood, with a likely energy source being matter ejected perpendicular to the accretion disc of the central black hole.
Hercules A | Galaxy
Scandinavian peoples, such as Swedes, have called the galaxy Winter Street ("Vintergatan") as the galaxy is most clearly visible during the winter at the northern hemisphere, especially at high latitudes where the glow of the Sun late at night can obscure it during the summer.
List of names for the Milky Way | Winter Street
NGC 1073 is a barred spiral galaxy in the constellation Cetus. The galaxy is estimated to be about 55 million light years from Earth, possess a disk spanning an estimated 80,000 light years in diameter, and likely contains a type of active core, called an HII nucleus. NGC 1073 is similar to the Milky Way only in their shared possession of a galactic bar. NGC 1073, however, does not possess the well-defined symmetrical arm structure the Milky Way exhibits, and retains a central bar larger than our home galaxy’s. NGC 1073 can be viewed with a mid-sized telescope in rural, dark skies.
NGC 1073 | Introduction
The reddened light from the center of the galaxy appears yellowish due to the intervening gas and dust located within the outer arms of NGC 2683. Its apparent magnitude is 10.6 making it not visible to the human eye without the aid of a small telescope.
NGC 2683 | Visibility
The band then continues the rest of the way around the sky, back to Sagittarius, dividing the sky into two roughly equal hemispheres.
Milky Way | Appearance
While the inner section of the galaxy shows a symmetrical two-arm structure, it has a single outer spiral arm that wraps 180° around the nucleus, giving the galaxy an overall asymmetric, lopsided appearance. The outer spiral arm has a red component that indicates a significant age. However, the existence of this structure is difficult to explain. The galaxy shows indications of recent starburst activity that may have terminated around 15 million years ago. The active central nucleus shows weak LINER behavior, and it may be an intermediate form between a LINER and an H II region. The luminosity of the X-ray source at the nucleus is in the 0.3–7 keV band.
NGC 1637 | Introduction
NGC 4874 is a giant elliptical galaxy. It was discovered by the British astronomer Frederick William Herschel I in 1785, who catalogued it as a bright patch of nebulous feature. The second-brightest galaxy within the northern Coma Cluster, it is located at a distance of 109 megaparsecs (350,000,000 light-years) from Earth. The galaxy is surrounded by an immense stellar halo that extends up to one million light-years in diameter. It is also enveloped by a huge cloud of interstellar medium that is currently being heated by action of infalling material from its central supermassive black hole. A jet of highly energetic plasma extends out to 1,700 light-years from its center.
NGC 4874 | Introduction
With a right ascension of and a declination of , this nebula may be found in the constellation of Dorado about 160 kly (50 kpc) away. Its apparent size is roughly 9′ 14″ × 12′ 15″. It lies at the northern side of the Large Magellanic Cloud's stellar bar, 15′ southeast of the center of rotation of the galaxy's neutral hydrogen.
N119 | Location
There is an HII region 1.8 arcseconds south of the nucleus and a diffuse H-alpha region, another HII region, observed 1.8 arcseconds north of the nucleus. The X-ray emission from the galaxy as observed by ROSAT can be explained as thermal emission from a hot interstellar medium and no hard component was detected.
NGC 1380 | Supermassive black hole and nucleus
NGC 3621 is a field spiral galaxy about away in the equatorial constellation of Hydra. It is comparatively bright and can be well seen in moderate-sized telescopes. The galaxy is around across and is inclined at an angle of 25° from being viewed edge on. It shines with a luminosity equal to 13 billion times that of the Sun. The morphological classification is SA(s)d, which indicates this is an ordinary spiral with loosely wound arms. There is no evidence for a bulge. Although it appears to be isolated, NGC 3621 belongs to the Leo spur. This galaxy has an active nucleus that matches a Seyfert 2 optical spectrum, suggesting that a low mass supermassive black hole is present at the core.
NGC 3621 | Introduction
NGC 4036 is the "New General Catalogue" identifier for a lenticular galaxy in the northern circumpolar constellation of Ursa Major. In the "Carnegie Atlas of Galaxies", it is described as being "characterized by an irregular pattern of dust lanes threaded through the disc in an 'embryonic' spiral pattern indicating a mixed S0/Sa form." It is located near the Big Dipper, a little to the north of the mid-way point between the stars Alpha Ursae Majoris and Delta Ursae Majoris. With a visual magnitude of 10.7, it can be dimly viewed using a aperture telescope. The visual dimensions of this galaxy are arc minutes, with the major axis having a position angle of 85°.
NGC 4036 | Introduction
NGC 5033 is an inclined spiral galaxy located in the constellation Canes Venatici. Distance estimates vary from between 38 and 60 million light years from the Milky Way. The galaxy has a very bright nucleus and a relatively faint disk. Significant warping is visible in the southern half of the disk. The galaxy's relatively large angular size and relatively high surface brightness make it an object that can be viewed and imaged by amateur astronomers. The galaxy's location relatively near Earth and its active galactic nucleus make it a commonly studied object for professional astronomers.
NGC 5033 | Introduction
Astronomers are confident that the Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System, in a region called Sagittarius A* because: Infrared observations of bright flare activity near Sagittarius A* show orbital motion of plasma with a period of at a separation of six to ten times the gravitational radius of the candidate SMBH. This emission is consistent with a circularized orbit of a polarized "hot spot" on an accretion disk in a strong magnetic field. The radiating matter is orbiting at 30% of the speed of light just outside the innermost stable circular orbit.
Supermassive black hole | In the Milky Way
This radiation is most likely coming from jets of energetic material being ejected by a central black hole. In 1996 it was revealed that this galaxy has a counter-rotating disk; around 20% of the stars in the galaxy are rotating in the opposite direction from the other 80%. The neutral and ionized gas in this galaxy are rotating in the same direction as the counter-rotating disk, and the stars in this group are generally younger than the main stellar population. This disk may have formed as the result of a merger with a gas-rich dwarf galaxy some four billion years ago.
NGC 4138 | Introduction
Consequently, the galaxy now looks "normal" in every way. Using five independent methods to estimate distances of heavenly bodies, a team of researchers from the Instituto de Astrofísica de Canarias (IAC) found the correct distance of NGC 1052-DF2 to be 42 million light years (13 MPc), not some 64 million light years (19 MPc) from the Earth. The total mass of the galaxy is around one-half of the mass estimated previously, but the mass of its stars is only about one-quarter of the previously estimated mass. This implies a significant part of NGC 1052-DF2 could be made up of dark matter, like any other galaxies.
NGC 1052-DF2 | Distance
The cluster is visible throughout the year from latitudes greater than 36 degrees north, with the longest visibility during Northern Hemisphere spring and summer. It is located at right ascension 16 41.7, declination +36° 28'. With an apparent magnitude of 5.8, it is barely visible with the naked eye on clear nights. Its diameter is about 23 arcminutes and it is readily viewable in small telescopes. Nearby is NGC 6207, a 12th-magnitude edge-on galaxy that lies 28 arcminutes directly northeast. A small galaxy, IC 4617, lies halfway between NGC 6207 and M13, north-northeast of the large globular cluster's center.
Messier 13 | Discovery and visibility
In the easternmost regions of the park, visitors with optimal vision can expect to see the Andromeda (M31) and Triangulum (M33) galaxies with unaided eyes. The central Milky Way appears highly structured to the naked eye from this site, and zodiacal light appears as a faint yellowish glow when visible. In the western regions of the park, the Andromeda Galaxy is still visible, and only the brightest structures around the Galactic Center of the Milky Way can be distinguished; zodicial light is visible halfway to the zenith.
Joshua Tree National Park | Astronomy
The galaxy appears very dim in the sky as it only has an apparent visual magnitude of 14.4. It can be classified as type E using the Hubble Sequence. The object's distance of roughly 240 million light-years from the Solar System can be estimated using its redshift and Hubble's law.
NGC 519 | Description
NGC 5970 can be seen 1° southwest of the star Chi Serpentis. A faint halo of dust can be seen around the galaxy's outer spiral arms.
NGC 5970 | Observations
The galaxy was observed by the Hubble Space Telescope. It was found that it has a central disk seen nearly face-on with a diameter of 1".8. Inside the disk is an inner ring with a diameter of circa 0".44 arcseconds, maybe part of a hardly visible spiral structure. There is also a linear dust feature sticking out of the disk with nearly the same axis as the radio jet. H-alpha and [N II] emission presented a peak at the centre of the dusk disk and also was found to form a ring around the peak, which had two brighter spots lying diametrically opposed.
NGC 541 | Introduction
NGC 3081 is known to feature an active galaxy nucleus which is categorised as type II Seyfert galaxy. Even though NGC 3081 shows significant absorption, it is Compton thin. Also it does not show spectral variability on monthly timescales in X-rays. In the nucleus of the galaxy is thought to exist a supermassive black hole whose mass upper limit is estimated to be between 8.5 and 37 million , based on the intrinsic velocity dispersion as measured by the Hubble Space Telescope. Observations obtained with the GMOS integral field spectrograph on the Gemini North telescope show a gas flow is present in the inner ≈ 2arcsec (200pc) of the galaxy, whose appearance is consistent with a bipolar outflow oriented along the north–south direction.
NGC 3081 | Active galactic nucleus
NGC 596 is an elliptical galaxy in the constellation Cetus. The galaxy lies 65 million light years away from Earth, which means, given its apparent dimensions, that NGC 596 is approximately 60,000 light years across. The galaxy shows an outer envelope and is a merger remnant. The surface brightness profil is smooth and featureless. The galaxy hosts a supermassive black hole, whose mass is estimated to be 170 million (10) formula_1. NGC 596 belongs at the NGC 584 galaxy group, which also includes the galaxies NGC 584, which lies 25 minutes to the northwest, NGC 600, NGC 615 and NGC 636.
NGC 596 | Introduction
Ia Hα images some HII regions were observed in the spiral arms. A dust spiral is seen in Hubble space telescope images extending to the centre. The lack of stellar gradient in the central regions and the data from Faint Object Camera, Faint Object Spectrograph and International Ultraviolet Explorer indicate that the galaxy had a starburst event approximately one billion years ago, possibly after the tidal interaction with another galaxy, which involved all the galaxy. Dynamical modeling of the velocity dispersions suggests that NGC 2681 hosts a supermassive black hole whose upper mass limit was set at 6×10 M⊙. As observed from Chandra X-ray Observatory, NGC 2681 displayed three stellar sources within the central kiloparsec of the galaxy.
NGC 2681 | Introduction
Although the galaxy is quite symmetric, the northern arms have HII regions that appear brighter than the southern ones. Also the southern arms appear less developed in their outer parts than the north ones. The star formation rate in NGC 2835 is 0.4 per year and the total stellar mass of the galaxy is low, at 7.9x10 . In the centre of NGC 2835 lies a supermassive black hole whose mass is estimated to be 3-10 million (10) , based on the spiral arm pitch angle. NGC 2835 is the foremost galaxy in a small group of galaxies, the NGC 2835 group.
NGC 2835 | Introduction
This 180° hemisphere of stars rotates clockwise once every 24 hours around a point directly overhead, where there do not happen to be any particularly bright stars.
Spherical Earth | Observation of constellations on North and South hemispheres at different seasons
The Galactic Center (or Galactic Centre) is the rotational center of the Milky Way galaxy; it is a supermassive black hole of 4.100 ± 0.034 million solar masses, which powers the compact radio source Sagittarius A*. It is away from Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest. There are around 10 million stars within one parsec of the Galactic Center, dominated by red giants, with a significant population of massive supergiants and Wolf-Rayet stars from star formation in the region around 1 million years ago.
Galactic Center | Introduction
The SMC is visible from the entire Southern Hemisphere, but can be fully glimpsed low above the southern horizon from latitudes south of about 15° north. The galaxy is located across both the constellations of Tucana and part of Hydrus, appearing as a faint hazy patch resembling a detached piece of the Milky Way. The SMC has an average apparent diameter of about 4.2° (8 times the Moon's) and thus covers an area of about 14 square degrees (70 times the Moon's). Since its surface brightness is very low, this deep-sky object is best seen on clear moonless nights and away from city lights.
Small Magellanic Cloud | Introduction
However, discoveries in the 2000s regarding the structure of the Milky Way may call this similarity into doubt, particularly because the latter is now believed to be a barred spiral, compared to the unbarred status of NGC 7331. In spiral galaxies the central bulge typically co-rotates with the disk but the bulge in the galaxy NGC 7331 is rotating in the opposite direction to the rest of the disk. In both visible light and infrared photos of the NGC 7331, the core of the galaxy appears to be slightly off-center, with one side of the disk appearing to extend further away from the core than the opposite side.
NGC 7331 | Introduction
The luminosity and size of this galaxy is mid-way between the Large and Small Magellanic Clouds. De Vaucouleurs and associates classed it as type SAc, suggesting more loosely wound arms. It is inclined at an angle of 65° to the line of sight from the Earth. Although appearing as a disk, there is evidence for a non-axisymmetric form of gas distribution, with a suggestion of central bar plus large-scale spiral arms. The inner structure contains many dark lanes and stellar condensations in its disk. There are two strong H II regions, one to each side. The overall star formation rate is y.
NGC 2976 | Introduction
Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way.
Galactic Center | Distance to the Galactic Center
The Sun is from the Galactic Center. This value is estimated using geometric-based methods or by measuring selected astronomical objects that serve as standard candles, with different techniques yielding various values within this approximate range. In the inner few kpc (around 10,000 light-years radius) is a dense concentration of mostly old stars in a roughly spheroidal shape called the bulge. It has been proposed that the Milky Way lacks a bulge formed due to a collision and merger between previous galaxies, and that instead it only has a "pseudobulge" formed by its central bar. However, confusion in the literature between the (peanut shell)-shaped structure created by instabilities in the bar, versus a possible bulge with an expected half-light radius of 0.5 kpc, abounds.
Milky Way | Galactic Center
PGC 6240 (also known as White Rose Galaxy) is a large lenticular galaxy in the constellation Hydrus. It is located about 346 million light-years away from Earth.
Principal Galaxies Catalogue | PGC 6240
RX J1242.6−1119A (often abbreviated RX J1242−11) is an elliptical galaxy located approximately 200 megaparsecs (about 650 million light-years) from Earth. According to current interpretations of X-ray observations made by the Chandra X-ray Observatory and XMM-Newton, the centre of this galaxy is a 100 million solar mass supermassive black hole which was observed to have tidally disrupted a star (in 1992 or shortly before). The discovery is widely considered to be the first strong evidence of a supermassive black hole ripping apart a star and consuming a portion of it.
RX J1242−11 | Introduction
NGC 4889 is located along the high declination region of Coma Berenices, south of the constellation Canes Venatici. It can be traced by following the line from Beta Comae Berenices to Gamma Comae Berenices. With an apparent magnitude of 11.4, it can be seen by telescopes with 12 inch aperture, but its visibility is greatly affected by light pollution due to glare of the light from Beta Comae Berenices. However, under very dark, moonless skies, it can be seen by small telescopes as a faint smudge, but larger telescopes are needed in order to see the galaxy's halo. In the updated Hubble sequence galaxy morphological classification scheme by the French astronomer Gérard de Vaucouleurs in 1959, NGC 4889 is classified as an E4 type galaxy, which means it has a flat distribution of stars within its width.
NGC 4889 | Properties
This star is very narrowly in the southern celestial hemisphere; this means that it can be observed from all the inhabited regions of the Earth without any difficulty and that it is invisible only far beyond the Arctic polar circle. It appears near or below the horizon, depending on season as circumpolar in innermost areas of the Antarctic continent. Being of magnitude 6.4, it is observable with the naked eye only in ideal conditions; it is easy to observe with a small pair of binoculars. The best period for the night-time observation of Orion in either hemisphere is between late October and April.
HD 34880 | Observation
The galaxy appears very dim in the sky as it only has an apparent visual magnitude of approximately 14 and thus can only be observed with telescopes. It can be classified as type G using the Hubble Sequence. The object's distance of roughly 159 million light-years from the Solar System can be estimated using its redshift and Hubble's law.
NGC 174 | Description
Several suggestions have been put forward to explain this puzzling observation, but none is completely satisfactory. For instance, although the black hole would eat stars near it, creating a region of low density, this region would be much smaller than a parsec. Because the observed stars are a fraction of the total number, it is theoretically possible that the overall stellar distribution is different from what is observed, although no plausible models of this sort have been proposed yet.
Galactic Center | Stellar population
NGC 5033 contains a Seyfert nucleus, a type of active galactic nucleus. Like many other active galactic nuclei, this galaxy's nucleus is thought to contain a supermassive black hole. The bright emission seen in visible light (as well as other wavebands) is partially produced by the hot gas in the environment around this black hole. Integral field spectroscopic observations of the center of NGC 5033 indicate that the Seyfert nucleus is not located at the kinematic center of the galaxy (the point around which the stars in the galaxies rotate). This has been interpreted as evidence that this galaxy has undergone a merger.
NGC 5033 | Nucleus
The northwest side of the galaxy is more strongly obscured by dust, suggesting it is the near side. The mass ratio of neutral hydrogen gas to the mass of the stars is 0.29, which is on the high side for a galaxy of this mass. Absolute luminosity is , and is calculated to contain of H I.
NGC 1566 | Introduction
Some of the 88 modern constellations visible are Ursa Major (including the Big Dipper), Cassiopeia, and Andromeda. The other six months of the year, the North Pole is in continuous daylight, with light from the Sun blotting out the stars. This phenomenon, and its analogous effects at the South Pole, are what defines the two poles. More than 24 hours of continuous daylight can only occur north of the Arctic Circle and south of the Antarctic Circle.) At the South Pole, a completely different set of constellations are visible during the six months of continuous nighttime, including Orion, Crux, and Centaurus.
Spherical Earth | Observation of constellations on North and South hemispheres at different seasons
Near NGC 4452's center is a slight bulge of stars, while hundreds of background galaxies are visible far in the distance. Galaxies that appear this thin are rare mostly because our Earth must reside (nearly) in the extrapolated planes of their thin galactic disks. Galaxies that actually are this thin are relatively common – for example our own Milky Way Galaxy is thought to be about this thin. NGC 4452 appears to be very similar to galaxy IC 335, an edge-on galaxy in Fornax Cluster, in constellation Fornax.
NGC 4452 | Introduction
A different method by Harlow Shapley based on the cataloguing of globular clusters led to a radically different picture: a flat disk with diameter approximately 70 kiloparsecs and the Sun far from the center. Both analyses failed to take into account the absorption of light by interstellar dust present in the galactic plane, but after Robert Julius Trumpler quantified this effect in 1930 by studying open clusters, the present picture of our host galaxy, the Milky Way, emerged.
Galaxy | Milky Way
Certain authors advocate that the Milky Way features two distinct bars, one nestled within the other. However, RR Lyrae variables do not trace a prominent Galactic bar. The bar may be surrounded by a ring called the "5-kpc ring" that contains a large fraction of the molecular hydrogen present in the Milky Way, as well as most of the Milky Way's star formation activity. Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way. X-ray emission from the core is aligned with the massive stars surrounding the central bar and the Galactic ridge. In 2010, two gigantic spherical bubbles of high energy emission were detected to the north and the south of the Milky Way core, using data from the Fermi Gamma-ray Space Telescope.
Milky Way | Galactic Center
There is a general lack of large scale continuous spiral structure in visible light, so it is considered a "flocculent galaxy". However, when observed in the near infrared, a symmetric, two-arm structure is seen. Each arm wraps 150° around the galaxy and extends out to from the nucleus. M63 is a weakly active galaxy with a LINER nucleus – short for 'low-ionization nuclear emission-line region'. This displays as an unresolved source at the galactic nucleus that is cloaked in a diffuse emission. The latter is extended along a position angle of 110° relative to the north celestial pole, and both soft X-rays and hydrogen (H-alpha) emission can be observed coming from along nearly the same direction.
Messier 63 | Introduction
With a declination of 56° 32' North, α Cassiopeiae is principally visible in the northern hemisphere. The star is detectable to most observers across the globe reaching as far south as Perth, Australia, Santiago, Chile and other settlements north ± 33° South latitude, albeit close to the horizon. α Cassiopeiae is located in line-of-sight of the Milky Way galaxy, so there are other notable celestial objects one can view close to this star—the Pacman Nebula, NGC 436 and NGC 457 being a few. Alpha Cas reaches its zenith above cities like Edinburgh, Copenhagen and Moscow. It is circumpolar throughout Europe, Russia, and as far south as Los Angeles, California on the North American continent as well as other locations around the globe having a latitude greater than ± 33° North.
Alpha Cassiopeiae | Visibility
The Solar System orbits within the Milky Way, a barred spiral galaxy that is a prominent member of the Local Group of galaxies. It is a rotating mass of gas, dust, stars and other objects, held together by mutual gravitational attraction. As the Earth is located within the dusty outer arms, there are large portions of the Milky Way that are obscured from view. In the center of the Milky Way is the core, a bar-shaped bulge with what is believed to be a supermassive black hole at its center. This is surrounded by four primary arms that spiral from the core.
Astronomy | Galactic astronomy
This is a type of active galaxy known as a LINER, which means that it shows emission lines of ionized gas in the region of its nucleus. Chemically, the stars at the center of the nucleus have a higher metallicity than in the neighboring regions. It appears that there is a tilted disk of stars orbiting the nucleus within a radius of . The galactic bulge itself appears triaxial with the ionized gas concentrated near the center of this bulge region. Images of the galaxy with the Hubble Space Telescope show a wispy disk of dust on all sides of the nucleus, with what appears to be the tendrilous remains of an ionization cone leading away 4 arc seconds to the northeast.
NGC 4036 | Introduction
From the South Pole, in good visibility conditions, the Southern Sky features over 2,000 fixed stars that are easily visible to the naked eye, while about 20,000 to 40,000 with the aided eye. In large cities, about 300 to 500 stars can be seen depending on the extent of light and air pollution. The farther north, the fewer are visible to the observer. The brightest stars are all larger than the Sun. Sirius in the constellation of Canis Major has the brightest apparent magnitude of –1.46; it has a radius twice that of the Sun and is 8.6 light-years away.
Southern celestial hemisphere | Observation
More detailed observations by the Very Large Array revealed a radio jet connecting the nucleus with the southwest lobe and a circumnuclear structure with a radius of nearly 300 pc. In the centre of the galaxy lies a supermassive black hole whose mass is estimated to be (10) based on Ks bulge luminosity. The X-ray spectra of the galaxy suggested the mass of the supermassive black hole to be in the range of 10 to 10 .
NGC 3367 | Nucleus
The nucleus is spherical in shape, showing no indication of oblateness. The prominent bar spans an angular distance of 48″ (48 arc seconds) across the galaxy along a position angle of 35.97° ± 0.35°. At 10″ southeast of the nucleus is a prominent region of star formation. The inner ring is about 43″.5 across. NGC 6217 has been characterized as a starburst galaxy, which means it is undergoing a high rate of star formation compared to a typical galaxy. As a result, the spectrum is dominated by stellar photoionization from young, hot stars. This component is less than 10 million years old, producing a blue-hued spectral continuum with absorption weak lines from elements other than hydrogen and helium.
NGC 6217 | Introduction
The AGN is radio-quiet with no evidence for a relativistic jet. It is powered by one of the largest known supermassive black holes: 23 billion solar masses (based on the molecular disk velocities); or alternatively 10 billion solar masses (based on reverberation mapping). The black hole is surrounded by an accretion disk of material spiraling into it, a few parsecs in size. Further out is a dust torus, a doughnut shaped cloud of dust and gas with a radius of about 100 parsecs. Both the accretion disk and dust torus appear to be almost face-on to us. The radiation from the molecular gas is coming from a flattened disk at the center of the galaxy with a radius of 550 pc.
APM 08279+5255 | Galactic structure
This is best seen in a long exposure photograph, which is obtained by locking the shutter open for most of the intensely dark part of a moonless night. The resulting photograph reveals a multitude of concentric arcs (portions of perfect circles) from which the exact center can be readily derived, and which corresponds to the Celestial pole, which lies directly above the position of the true pole (North or South) on the horizon. A published photograph exposed for nearly 8 hours demonstrates this effect. The Northern Celestial pole is currently (but not permanently) within a fraction of 1 degree of the bright star Polaris.
Cardinal direction | Astronomy
The galaxy can be observed edge-on from Earth, thus appearing very elongated. It can be classified as spiral galaxy of type Sbc using the Hubble Sequence. The object's distance of roughly 120 million light-years from the Solar System can be estimated using its redshift and Hubble's law.
NGC 522 | Description
The Greek philosopher Democritus (450–370 BCE) proposed that the bright band on the night sky known as the Milky Way might consist of distant stars. Aristotle (384–322 BCE), however, believed the Milky Way to be caused by "the ignition of the fiery exhalation of some stars that were large, numerous and close together" and that the "ignition takes place in the upper part of the atmosphere, in the region of the World that is continuous with the heavenly motions." The Neoplatonist philosopher Olympiodorus the Younger (–570 CE) was critical of this view, arguing that if the Milky Way is sublunary (situated between Earth and the Moon) it should appear different at different times and places on Earth, and that it should have parallax, which it does not.
Galaxy | Milky Way
PGC 6240, also known as AM 0139-655 or the White Rose Galaxy, is a very large and old galaxy in the southern constellation of Hydrus, about 345 million light years away from Earth. Appearing like a white rose in the sky, the galaxy has foggy shells of stars that rotate around a luminous center with few shells lying close to it while others at a distance. Those distant from the center appear disconnected from the white rose. The age of globular clusters in this galaxy is variable. They include a population of relatively young globular clusters around 400 million years old, another group of older ones around 1 billion years old, and other ones even older than that.
PGC 6240 | Introduction
The diameter of each of the bubbles is about ; they stretch up to Grus and to Virgo on the night-sky of the southern hemisphere. Subsequently, observations with the Parkes Telescope at radio frequencies identified polarized emission that is associated with the Fermi bubbles. These observations are best interpreted as a magnetized outflow driven by star formation in the central of the Milky Way.
Milky Way | Galactic Center
NGC 2573 (also known as Polarissima Australis) is a barred spiral galaxy located in the constellation Octans, discovered in 1837 by John Herschel. It is the closest NGC object to the South Celestial Pole.
NGC 2573 | Introduction
NGC 681 (also known as the Little Sombrero Galaxy) is an intermediate spiral galaxy in the constellation of Cetus, located approximately 66.5 million light-years from Earth. The name Little Sombrero Galaxy is a reference to a much larger and earlier observed sombrero-like galaxy designated M104, or the Sombrero Galaxy.
NGC 681 | Introduction
CGCG 196-041, HOLM 739A, CGCG 1618.0+3754, PGC 057842, CGPG 1618.0+3754, UZC J161948.1+374628, MCG +06-36-029, FIRST J161948.0+374628, 2MASX J16194809+3746282, NVSS J161948+374628, 2MASXi J1619480+374627, [M98j] 251 NED01, IRAS 16180+3753, [SLK2004] 1229, IRAS F16180+3753, ISOSS 078 NGC 6120 is a spiral galaxy located probably 135 million light years away from Earth. It is visible at coordinates of right ascension 16h 19m 48.1s and the declination of +37° 46′ 28″, in the constellation Corona Borealis.
NGC 6120 | Introduction
This oblong spiral galaxy with 6.9 by 3.0 arcminutes and 26,000 light-years in diameter, is located 13 million light-years away from Earth and lies 4 degrees off the galactic plane. It is the closest Seyfert galaxy to the Milky Way, and therefore hosts an active galactic nucleus. Circinus X-1 is an X-ray binary star system that includes a neutron star. Observations of Circinus X-1 in July 2007 revealed the presence of X-ray jets normally found in black hole systems. Located at 19,000 light-years, the pulsar PSR B1509-58, also called the Circinus Pulsar, has expelled a 20-light-year-long jet of material from its southern pole, clearly visible in the X-ray spectrum.
Circinus | Deep-sky objects
The evolutionary picture appears to be lent weight by the fact that the disks of spiral galaxies are observed to be home to many young stars and regions of active star formation, while elliptical galaxies are composed of predominantly old stellar populations. In fact, current evidence suggests the opposite: the early Universe appears to be dominated by spiral and irregular galaxies. In the currently favored picture of galaxy formation, present-day ellipticals formed as a result of mergers between these earlier building blocks; while some lenticular galaxies may have formed this way, others may have accreted their disks around pre-existing spheroids.
Hubble sequence | Physical significance
Except in areas close to the equator, Deneb permanently circles the North pole. The orientation of Deneb and Sadr would make a useful clock hand for telling sidereal time. Mars's north celestial pole is also only a few degrees away from the galactic plane. Thus the Milky Way, especially rich in the area of Cygnus, is always visible from the northern hemisphere.
Astronomy on Mars | Celestial poles and ecliptic
But it is small, appearing only 4' by 2'. The morphological classification of this galaxy is SAB(rs)bc, indicating a spiral galaxy with a weak central bar (SAB), an incomplete ring structure around the bar (rs), and moderately–wound arms (bc). The plane of the galactic disk is inclined by 64° to the line of sight from the Earth, with the major axis aligned along a position angle of 178°. Within the galaxy's core is an active galactic nucleus tentatively classified as a type I Seyfert. The central supermassive black hole has a relatively low mass, estimated as . The core is a source for X-ray emission that is seen to vary dramatically on time scales as low as hours.
NGC 7314 | Introduction
The "Webb Society Deep-Sky Observer's Handbook" writes the following about NGC 55: "Nearly edge-on and appears asymmetrical with some signs of dust near the bulge, which is diffuse, broad and somewhat elongated with the south edge sharp; southeast of the bulge it is strongly curved and lined with 4 or 5 faint knots; north edge of the curve is sharp." Burnham calls it "one of the outstanding galaxies of the southern heavens", somewhat resembling a smaller version of the Large Magellanic Cloud.
NGC 55 | Visual appearance
From a viewpoint in the LMC, the Milky Way's total apparent magnitude would be −2.0—over 14 times brighter than the LMC appears to us on Earth—and it would span about 36° across the sky, the width of over 70 full moons. Furthermore, because of the LMC's high galactic latitude, an observer there would get an oblique view of the entire galaxy, free from the interference of interstellar dust that makes studying in the Milky Way's plane difficult from Earth. The Small Magellanic Cloud would be about magnitude 0.6, substantially brighter than the LMC appears to us.
Extraterrestrial sky | From the Large Magellanic Cloud
The inner part of the galaxy shows a complex structure with multiple spiral arms, which becomes a symmetric, double arm pattern beyond 49″ from the core. The central bulge is relatively young with an estimated age of two billion years, while the nucleus is inactive. In 2007, a supernova explosion was discovered in the galaxy from images taken on February 19 from the 1 m Swope telescope at Las Campanas Observatory in Chile. Designated SN 2007aa, it was a type IIP supernova positioned 68″.5 north and 60″.8 east of the galactic nucleus. The progenitor was a red giant star with 8.5–16.5 times the mass of the Sun.
NGC 4030 | Introduction
It is a relatively small, compact spiral with a diameter of , multiple flocculent arms and a bright, dusty nucleus that does not appear to be active. However, the neutral hydrogen in the galaxy is spread over a diameter five times larger than its visible size. Although it appears nearly face-on, the galactic plane is inclined by an angle of 28° to the line of sight from the Earth, with the major axis being oriented along a position angle of 116°. The outer part of the disk appears to be warped, so that the major axis is not quite perpendicular to the minor axis, and the morphology is somewhat disrupted.
NGC 278 | Introduction
The profile of the galaxy is irregular, with the northwest side having a much higher surface brightness than the southeast side. Also, one half of the galactic disk appears thicker that the other. A number of irregular dust lanes are observed across the disk, but none is prominent. No bulge is observed. A population of older stars has been detected off the center of the disk, as well as a stream-like structure, that could indicate a galaxy merger took place in the recent past. The galaxy is close enough that its stars can be resolved with large telescopes, with the brightest ones having an apparent magnitude of 21.
IC 5052 | Introduction
NGC 1964 is a barred spiral galaxy in the constellation Lepus. The galaxy lies 65 million light years away from Earth, which means, given its apparent dimensions, that NGC 1964 is approximately 100,000 light years across. At its center lies a supermassive black hole, with estimated mass 2.5 × 10 . The galaxy features two tightly wound inner spiral arms within a disk with high surface brightness and two outer, more open spiral arms that originate near the inner ring. The outer arms feature few small HII regions. NGC 1964 is the main galaxy in a group of galaxies, known as NGC 1964 group, which also includes the galaxies NGC 1979, IC 2130 and IC 2137.
NGC 1964 | Introduction
NGC 660 is a peculiar and unique polar-ring galaxy located approximately 45 million light years from Earth in the Pisces constellation. It is the only such galaxy having, as its host, a "late-type lenticular galaxy". It was probably formed when two galaxies collided a billion years ago. However, it may have first started as a disk galaxy that captured matter from a passing galaxy. This material could have, over time, become "strung out" to form a rotating ring. The ring is not actually polar, but rather has an inclination from the plane of the host disk of approximately 45 degrees.
NGC 660 | Introduction
A large doughnut-shaped cloud appears in North polar region of Mars around the same time every Martian year and of about the same size. It forms in the morning, dissipates by the Martian afternoon. The outer diameter of the cloud is roughly , and the inner hole or eye is across. The cloud is thought to be composed of water-ice, so it is white in color, unlike the more common dust storms. It looks like a cyclonic storm, similar to hurricane, but it does not rotate. The cloud appears during the northern summer and at high latitude. Speculation is that this is due to unique climate conditions near the northern pole.
Planum Boreum | Repeating annular cloud
NGC 2681 is a lenticular galaxy in the constellation Ursa Major. The galaxy lies 50 million light years away from Earth, which means, given its apparent dimensions, that NGC 2681 is approximately 55,000 light years across. NGC 2681 has an active galactic nucleus and it is a type 3 Seyfert galaxy. Its nucleus is also a low-ionization nuclear emission-line region. NGC 2681 has possibly three bars, with a relatively large bar at the outer side. Because the galaxy is seen nearly face-on, the bar like structures cannot be projection effects. From earth based observations, in B-I images the galaxy showed neither grand design spirals nor a ring, but only two symmetrical spiral arms starting from the end of the primary bar.
NGC 2681 | Introduction
With binoculars it can be seen to cover an area three quarters the size of the full moon. It lies 1.5 degrees east of 5th-magnitude Omega Pavonis. The nearest bright star is Peacock, which lies 3.25 degrees north and 9.25 degrees east.
NGC 6752 | Introduction
NGC 7052 is an elliptical galaxy in the constellation Vulpecula. The galaxy harbours a supermassive black hole with mass c. 220-630 million solar masses in its nucleus.
NGC 7052 | Introduction
NGC 5101 is a lenticular galaxy in the constellation Hydra. It is separated in the sky from the spiral galaxy NGC 5078 by about 0.5 degrees, and both are believed to be at the same distance from the Earth. This would mean they are approximately 800,000 light-years apart. Both galaxies are believed to be about the size of the Milky Way.
NGC 5101 | Introduction
The Black Eye Galaxy (also called Evil Eye Galaxy and designated Messier 64, M64, or NGC 4826) is a relatively isolated spiral galaxy located 17 million light-years away in the northern constellation of Coma Berenices. It was discovered by Edward Pigott in March 1779, and independently by Johann Elert Bode in April of the same year, as well as by Charles Messier in 1780. A dark band of absorbing dust in front of the galaxy's bright nucleus gave rise to its nicknames of the "Black Eye" or "Evil Eye" galaxy. M64 is well known among amateur astronomers because of its appearance in small telescopes.
Black Eye Galaxy | Introduction
The North America Nebula covers a region more than ten times the area of the full moon, but its surface brightness is low, so normally it cannot be seen with the unaided eye. Binoculars and telescopes with large fields of view (approximately 3°) will show it as a foggy patch of light under sufficiently dark skies. However, using a UHC filter, which filters out some unwanted wavelengths of light, it can be seen without magnification under dark skies. Its shape and reddish color (from the hydrogen Hα emission line) show up only in photographs of the area. The portion of the nebula resembling Mexico and Central America is known as the Cygnus Wall.
North America Nebula | General information
NGC 973 is seen edge-on, with an inclination of nearly 90°. Its bulge is shaped like a box or peanut. The subtraction of axisymmetric components from the profile of the galaxy showed that its bulge has an X-like morphology, which indicates the presence of a bar. A prominent dust lane runs across the galaxy. The galaxy kinematics revealed that the northeast side is the approaching one and the southwest is receding. The disk appears flat, without warps. The total hydrogen mass of the galaxy is estimated to be about , and the total dust mass is estimated to be , with clumpy distribution.
NGC 973 | Characteristics
Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated visible diameter between 170,000 and 200,000 light-years (ly). It is estimated to contain 100–400 billion stars and at least that number of planets. The dark matter halo around the Milky Way may span as much as 2 million light years. The Solar System is located at a radius of about 27,000 light-years from the Galactic Center, on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust.
Milky Way | Introduction
Further analysis gave an estimate about the amount of mass needed for the gravitational pull, which proved to be too much for a neutron star. After more observations confirmed the results, by 1973, the astronomical community generally recognized black hole Cygnus X-1, lying in the plane of the Milky Way galaxy at a galactic latitude of about 3 degrees.
Tom Bolton (astronomer) | Career
The galaxy's large apparent size can be attributed to the fact that it is face-on. Despite its size, it only has an apparent visual magnitude of 11.7. It can be classified as spiral galaxy of type SBbc using the Hubble Sequence. The object's distance of roughly 220 million light-years from the Solar System can be estimated using its redshift and Hubble's law.
NGC 521 | Description
The Andromeda Galaxy is the most distant object and the only spiral galaxy outside our Milky Way able to be seen with the naked eye. The galaxy is commonly located in the sky in reference to the constellations Cassiopeia and Pegasus. Andromeda is best seen during autumn nights in the Northern Hemisphere when it passes high overhead, reaching its highest point around midnight in October, and two hours later each successive month. In early evening, it rises in the east in September and sets in the west in February. From the Southern Hemisphere the Andromeda Galaxy is visible between October and December, best viewed from as far north as possible.
Andromeda Galaxy | Amateur observing