Virtual planisphere
Planets
Mercury
Athough Mercury is the closest planet to the Sun, it’s the second hottest, behind Venus. Mercury’s orbit ranges from 46 to 70 million km from the sun, giving it the highest temperature range in the Solar System. Its thin atmosphere consists of atoms blasted off its surface by the solar wind.
Mercury is the second densest planet, following Earth, due to a large iron core, which has an estimated radius of between1800 to1900km.
The surface of Mercury is old; it has so many craters that it resembles the Earth’s Moon. It revolves about the Sun once every 88 Earth days, and is the second smallest planet in the Solar System.
Caloris Basin
A giant asteroid smashed into the surface of Mercury at an early stage in the planet’s history, forming the Caloris Basin. The 1300 km diameter basin filled with lava, then cooled.
The basin sits directly under the Sun when Mercury is closest to the Sun, so it is the hottest place on Mercury’s surface.
Hills of Mercury
On the opposite side of Mercury from the Caloris Basin lie the Hills of Mercury. They were probably formed as the shock wave produced from the Caloris impact was reflected and focused to this point, causing the crust to crack into a series of complex blocks. This strange terrain covers an area of about 100 kilometres.
Bright rayed craters
At 40km in diameter, these bright rayed craters are prominent features of Mercury. The halos and rays cover other features on the surface, which indicates that they are some of the youngest on Mercury.
Double ring craters
Double ring craters are common features of Mercury, and a faint one can be seen at the upper right of this image. The outer ring is 170 kilometres across, and it is located at 35 degrees S. Lat. This particular double ring crater has a bright rayed crater to its left. Double ring craters are usually larger than 100km across and have smooth floors. The inner ring is at a lower elevation to the outer ring.
Mercury’s southern hemisphere
Water may exist in deep craters at Mercury’s poles, where the floors of the craters remain in deep shadow. It has a very thin atmosphere, created when atoms are blasted off its surface by the solar wind. These atoms quickly escape into space. This image is a composite made from images from the Mariner 10 spacecraft, which passed by Mercury in 1974.
Venus
Venus, the second planet from the sun, is similar to the Earth in size, mass, density and volume. It’s the hottest planet in the Solar System, with a surface temperature that will melt lead. It has a day of 243 Earth days, and a shorter year, only 225 Earth days. It rotates on its axis in a clockwise direction, the opposite of the other eight planets. Its orbit is the most circular of all the planets, with only 1% deviation.
Alpha Regio
The terrain of Alpha Regio is a strong radar reflector. It consists of a series of troughs, ridges and faults that are up to four kilometres high. The radar-dark regions are topographical lows, which are often filled with volcanic lavas. The source of the volcanism appear as bright spots within the smooth plains. This 1300 kilometre region was the first feature on Venus to be identified from Earth-based radar.
Complex crater 'Dickinson'
The “Dickinson” impact crater is 69 kilometres in diameter. It is characterised by a partial central ring and a flooded floor, which may be either lava, or material melted upon impact. The rough area around the crater is made up of material that was ejected on impact. This image was taken from the Magellan spacecraft’s mission to Venus in 1990.
Sedna Planitia
This perspective generated by computer from the Magellan data shows part of the lowland region Sedna Planitia. The circular depressions and associated fracture patterns are unique to the lowlands of Venus and are called ‘coronae’. Coronae are thought to be caused by localized hot spot magmatic activity under the surface of Venus. The magma pushes up the surface of the crust, which cools, causing the depression and the fractures.
Earth
Earth, the third planet from the Sun is the only planetary body in the Solar System known to support life. Earth is also unique in that it is the only planet in the Solar System on which water can exist in liquid form on the surface. 71% of the Earth’s surface is covered with water.
Earth is the third planet from the Sun and the fifth largest. It is the densest major body in the Solar System. It is tilted 23.4 degrees off axis, which creates seasonal temperature variations.
Mount Etna
This spectacular image shows advancing lava flows on the southern flank of Mount Etna, Italy, one of the most active volcanoes on Earth. Glowing summit craters above the main lava flows, and a small fissure eruption are also visible. The bright puffy clouds were formed from water vapour released during the eruption. This image was taken by NASA’s Terra spacecraft at 250 metre resolution on 29th July 2001.
Oahu
This is the island of Oahu, Hawaii. The Hawaiian islands are created from volcanic mountains, and are among the greatest mountain ranges on earth. They rise an average of 4,572 meters to reach sea level from their base on the sea floor.
This image was taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer instrument on NASA’s Terra spacecraft on June 3, 2000.
Mars
Mars, with its global swirling orange dust storms, its frosty white water ice clouds over a rusty red landscape, is a dynamic planet. When the southern hemisphere is in summer, ferocious windstorms suck air into the upper atmosphere creating a global blanket of dust.
Smaller than Earth, Mars is the fourth planet from the Sun. Its orbit is significantly elliptical, resulting in a wide temperature range. Mars has one of the most highly varied and interesting terrains of any of the terrestrial planets.
Olympus Mons
Olympus Mons is a giant volcano, the largest mountain in the Solar System. Rising 27 km above the surrounding plain, it is more than 500 km in diameter at its base and is rimmed by a cliff 6 km high. In some places this cliff is hidden under lava flows that cascade out onto the surrounding lava plains. The unusual rough crinkly patches around the volcano form the Olympus Mons Aureole.
Valles Marineris
The mesas and mounds found in the giant canyon system Valles Marineris have layers in them, leading to speculation that they are sediment deposited by water. The area has been subsequently eroded. The Valles Marineris canyon system is 4000 km long and from 2 to 7 km deep.
Isidis Planitia
This three km wide image shows a line of possibly volcanic cones in Isidis
Planitia. It is planned that the Beagle 2 spacecraft will land in this general area at the end of 2003.
Southwest of a gap in the line of cones in the southern part of the image, curved sand dunes can be seen. There are several impact craters, of which the largest is at the top right.
Jupiter
Jupiter, the gas giant, is the largest planet in our Solar System. Although what we see of Jupiter is the tops of clouds, it is believed that it has a core of rock and icy material, surrounded by a thick layer of liquid metallic hydrogen and helium. It contains more matter than all of the other planets combined, and its rapid rotation causes it to flatten at the poles and bulge at the equator. Jupiter radiates more energy into space than it receives from the Sun.
Great Red Spot
The Great Red Spot is a vast storm, some 14 000 km from north to south and 26 000 km from east to west, bigger than two Earths. It is the largest known storm in the Solar System, and is believed to have been raging for more than 300 years, with no signs of slowing. It rotates anticlockwise and completes one rotation every six days.
Satellite footprints seen in Jupiter Aurora
This spectacular image is of an electric-blue aurora glowing off the north pole of Jupiter. High-energy electrons race along the planet's magnetic field and into the upper atmosphere where they excite atmospheric gases, causing them to glow. This image shows the magnetic “footprints” of three of Jupiter’s largest moons, Io (along the left hand limb), Ganymede (near the centre) and Europa (below and to the right of Ganymede’s footprint).
Jupiter and Io
This image of Jupiter and Io was taken at a distance of 24 million km by the Voyager 2 spacecraft, on the 10 July 1979. Io can be seen to the right. The shadow from Jupiter’s largest moon, Ganymede can be seen on the Jovian cloud tops to the left.
Eruption on Io
This image of Jupiter’s moon Io shows two volcanic eruptions. The eruption seen on the edge of the planet is 140km high and shows the plume from the volcano Pillan Patera. Near the centre of the image you can see the volcano Prometheus erupting. A bluish dark plume surrounds it and its reddish shadow can be seen on the planet’s surface on the right.
Saturn
In many ways, Saturn is similar to Jupiter. It is the second largest planet in the Solar System, and is visibly flattened at the poles, a result of the very fast rotation on its axis. Saturn is mostly hydrogen and helium, and it is the only planet that is less dense than water. It radiates more energy than it receives from the sun.
Saturn has seven rings, and although they appear solid, they are made up of individual particles, ranging in size from a centimetre to several metres. These particles are made up of water ice and rock.
F-Ring
The bizarre F-Ring is Saturn's outermost ring, occurring some 4000 km beyond the edge of Saturn's main ring system. It is a complex structure made up of two narrow, braided, bright strands along which "knots" are visible. Each strand has a similar, but not identical orbit. Scientists speculate that the knots may be clumps of ring material, or mini moons.
Great White Spot
Saturn’s Great White Spot is a giant storm that appears about every thirty years, last appearing on September 24th 1990, in the mid-summer of the northern hemisphere. It rapidly grew to an oval big enough to swallow three Earths, stayed the same size for about three weeks, then 1,700 km/hr winds made it get even larger, as seen here. Ammonia gas, warmed by the summer sun, freezes in the upper atmosphere to create the white ammonia ice crystals, which are then whipped around the planet by the storm.
Red Spot
Saturn sometimes has a Red Spot, like Jupiter except that it is considerably smaller at about 6,000 km across, and does not last as long. The storm is in the southern hemisphere and is thought to be composed of phosphine that is brought high into the upper atmosphere by spiralling convection currents.
Uranus
The gas planet Uranus is the third largest in our Solar System. Unlike the other planets, Uranus rotates on its side. As a result, Uranus’ polar regions receive more energy from the sun than do its equatorial regions.
Uranus’ greenish colour is the result of the absorption of red light by methane in the upper atmosphere. It has faint bands of clouds, like the other gas planets, but these can only be seen with radical image enhancement. Uranus has 11 faint rings, and 21 moons. A day on Uranus is 17 hours and 14 minutes long.
Miranda
Miranda is the innermost of Uranus' large moons. It has a diameter of 470 km, and its surface is a jumble of fault canyons 20 km deep, terraces layers, and old and young surfaces. Miranda is about half water ice and half rocky material. Scientists believe that Miranda may have been shattered as many as five times during its formation, with the moon re-assembling itself after each event.
Uranus’ rings
Like the other gas planets, Uranus has rings. They are very dark and are composed of fairly large particles. There are 11 known rings, all of which are very faint. The brightest is known as the Epsilon ring, is to the right of this image. Between the rings lie broad lanes of cosmic dust.
Discrete cloud
This false colour Voyager 2 image of Uranus shows a discrete cloud as a bright streak near the planet’s limb. The cloud is one of the most prominent atmospheric features seen by the spacecraft. The donut shaped feature is an artefact of the camera optics. The different colours indicate variations in vertical structure, possibly due to smog-like constituents in the planet’s atmosphere.
Neptune
Neptune is very similar in composition to Uranus. It is mostly made up of gases, but probably has a small rocky core, about the mass of the Earth. Its soft blue colour is due to the absorption of red light by methane in its atmosphere. It is made up of ices, rock, hydrogen, helium, methane, and an unidentified substance that gives its clouds their rich blue colour.
Neptune is the fourth largest planet in diameter, although it is actually also larger in mass than Uranus. Like the other gas planets, Neptune has rings, which are very dark and are of unknown composition.
Great Dark Spot
The Great Dark Spot of Neptune was a gigantic storm system in the planet’s atmosphere, photographed here in 1989. It was lower in altitude than the feathery white cirrus clouds that float above it. Neptune’s winds blew it westward at 300 meters/second as it rotated counter-clockwise across the planet’s surface. The smallest features seen in this image are 50km across. It cannot be seen at the moment so it has either dissipated or is currently being masked by other aspects of the atmosphere.
Neptune’s rings
Some of Neptune’s outermost rings are diffuse, dusty sheets, others have mysterious unevenly spaced clumps of dense material. These concentrations of ring material is puzzling, the material should have spread evenly around the ring in a few years. One theory is that nearby moonlets, too small to detect directly, are interacting with the rings to form the clumps. One of the rings appears to have a curious twisted structure.
Scooter
The small, white triangle below the Great Dark Spot was nicknamed Scooter by scientists here on Earth. It moves around Neptune at about 42 degrees Southlatitude and is madeupof bright cloud bands, which change shape. It was called Scooter, because it zipped across the planet faster than the Great Dark Spot, once every 16 hours. Its true nature remains a mystery.
Pluto
Pluto is the farthest planet from the Sun and by far the smallest; it is even smaller than seven of the Solar System's moons. It is the only planet not to have been visited by spacecraft and even the Hubble Space Telescope can resolve only the largest features on its surface. Little is known about Pluto’s composition and atmosphere, but it is probably a mixture of 70% rock and 30% water ice and its atmosphere probably consists primarily of nitrogen with some carbon monoxide and methane.
Pluto and Charon
This is Pluto and its only known satellite. The moon Charon’s composition is unknown, but its low density indicates that it may be similar to Saturn's icy moons. Its surface seems to be covered with water ice, this is quite different from Pluto.
Pluto surface details
This is the first image-based surface map of Pluto. It was assembled by computer image processing software from four separate images of Pluto's disk taken by Hubble.
The Sun
The Sun is by far the largest object in the Solar System.It is an ordinary G2 star, one of more than 100 billion stars in our galaxy. Some 99.8% of the total mass of all the matter between the Sun and halfway to the nearest star is contained within its surface.
The temperature at the Sun’s core is 15.6 million K, and the pressure is 250 billion atmospheres. This picture shows a solar prominence, a dramatic eruption from the surface of the Sun, caused by magnetic fields. This image was obtained at an ultraviolet wavelength emitted by helium atoms that have lost one electron.
Sunspots
Every 11 years, the Sun goes through a period of activity known as the “solar maximum”, during which there are sunspots, solar flares and coronal mass ejections. Sunspots are “cool” regions of the Sun’s surface, only 3800 K as opposed to the sun’s normal 5800 K. They can be up to 50,000 km in diameter and only look dark by comparison with the surrounding regions. They are caused when the Sun’s magnetic field lines just below the surface poke through the solar photosphere.
Total solar eclipse
This is a full solar eclipse (14th April 1992). Total eclipses occur when the Moon lines up between the Earth and the Sun and it projects its shadow onto the Earth. An eclipse of the sun can only happen at New Moon, which occurs every 29.5 days. The Moon’s orbit around the Earth is tilted 5 degrees to the Earth’s orbit around the Sun, so the Moon’s shadow usually misses the Earth. There are at least two eclipses of the Sun each year, but most are only partial.
Halley’s Comet
Halley's Comet, has been known since at least 240 BC and possibly since 1059 BC. Its orbit brings it near the Earth on average every 76 years. It was visible in 1910 and again in 1986, and its next perihelion passage will be in 2061. The nucleus of Halley is ellipsoidal in shape and measures approximately 16 by 8 by 8 kilometres. This image is of the nucleus of Comet Halley was taken by the Giotto spacecraft on 13th March 1986.
Borrelly Comet
Comet Borrelly's ice and rock nucleus stretches about 8 km from end to end and looks quite like a bowling pin. This image, taken on 25th September 2001, shows a comet with rugged terrain, smooth rolling plains, deep fractures and dark material. Borrelly surprised scientists as they expected a symmetrical flow of the solar wind around it, but instead the coma jetted off to one side.
Linear WM1 Comet
Comet Linear WM1 was discovered in 2000 when it was out past Jupiter and still very faint. As it approached Earth, it brightened sooner than expected, and a narrow anti-tail became visible. It reached its nearest approach to the sun in late January 2002. Astronomers were particularly interested in it because its ion tail might help us understand solar winds expelled from near the sun's poles.
Star constellations
Orion
Orion is one of the most easily recognised of all constellations in the northern sky. It represents Orion, the hunter. Three bright stars in a straight line form Orion’s Belt, visible on the southern horizon in winter evenings. Three fainter stars make up his sword. The central star is not really a star at all, but is the Great Orion Nebula (also known as M42). This is it, easily visible with the naked eye as the “fuzzy” star in the middle of Orion’s sword.
M43 - Orion - Diffuse Nebulosity
This is M43, known as De Mairan’s Nebula, the part of the Great Orion Nebula located within Orion’s sword that is slightly separated from the main nebulosity by a dark turbulent lane. It is seen as the comma-shaped cloud surrounding an eighth magnitude star just north of the Great Nebula.
M42b - Orion - Diffuse Nebulosity
This is the bright central region of M42, the diffuse nebulosity within Orion’s sword. It is an irregular cloud about six light-years across. The four stars in the centre (the Trapezium) have recently formed and provide the energy to light up the nebula.
M42 - Orion - Diffuse Nebulosity
This is the central region of M42 in the Great Orion Nebula within Orion’s sword, showing more clearly the four stars in the centre that provide energy to light up the nebula.
Horsehead - Orion - Dark Nebula
As well as the luminous bright nebulae that consist of light emitting gas or illuminated dust masses, there are dark nebulae which can be seen because they obscure the light coming from stars or bright nebulae behind them. This is the ‘Horsehead Nebula’, one of the most identifiable nebulae in the sky. It is located within the constellation Orion, and is part of a large, dark, molecular cloud. The large star near the centre of the image is zeta Orionis, the easternmost of the three stars that make up Orion’s Belt.
Horsehead - Orion - Dark Nebula
This is a close up of the ‘Horsehead Nebula’. The red glow originates from hydrogen gas predominantly behind the dark cloud, running north-south, which is ionised by the nearby bright star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick dust.
Sagittarius
Sagittarius is one of the richest constellations in the sky, filled with numerous nebulae, along with their associated open star clusters. M8, the ‘Lagoon Nebula’ is situated in a very conspicuous field of the Milky Way in Sagittarius, towards the bottom of this image. Nearby is the Trifid Nebula (M20) and a rich star field and faint nebulae surrounding them.
M8 - Sagittarius - Diffuse Nebulosity
The ‘Lagoon Nebula’, M8, is one of the finest cluster/nebula combinations in the sky. One of the remarkable features of the Lagoon Nebula is the dark “globules” which are collapsing protostellar clouds. The large, scattered open cluster lies at the eastern edge of a large, swirling cloud of nebulosity. The nebula has obvious dark lanes and looping patterns. This is also quite easily seen by both the naked eye and in binoculars, within Sagittarius.
M20 - Sagittarius - Diffuse Nebulosity
The Trifid Nebula, M20, is famous for its three lobed appearance, where three intersecting dark lanes meeting near its centre more or less equally divide the centre patch of light. The red emission nebula with its young star cluster is surrounded by a blue reflection nebula, which can be seen as the soft purple edges of this image.
M17 - Sagittarius - Nebula and Cluster
This is M17, the ‘Omega’ or ‘Swan Nebula’, a nebula and cluster within the constellation Sagittarius. It is a star nursery and shines by excited emission, caused by the higher energy radiation of young stars that are hidden in the nebula. The pink colour comes from the hot hydrogen gas which is excited to shine by the hottest stars which have just formed within the nebula.
Cygnus
Gamma Cygni - Cygnus - Diffuse Nebulosity
Cygnus or ‘the Swan’ is a conspicuous constellation in the northern hemisphere. The stars forming the swan’s body resemble a cross, so sometimes this constellation is referred to as the ‘Northern Cross’. The brightest star, Deneb, is among the 20 brightest stars in the sky.
This is gamma Cygni, the central and third brightest star in the constellation Cygnus. It has a large area of emission nebulosity surrounding it. The two sections of nebulosity above gamma Cygni are called the Butterfly Nebula.
NGC7000 (North American Nebula) - Cygnus - Diffuse Nebulosity
The NGC7000, is also known as the ‘North American Nebula’ because it resembles the North American continent. It is a bright emission nebula at about 3 degrees east of Deneb, in the constellation Cygnus, and it is about 1500 light years away.
Perseus
Double Cluster - Perseus - Open Cluster
The constellation Perseus is one of the larger constellations of the northern hemisphere. The body of Perseus extends almost parallel to the Milky Way.
Open clusters are groups of stars that are physically related and held together by mutual gravitational attraction. They are believed to originate from large cosmic gas and dust clouds in the Milky Way, and to continue to orbit the galaxy. This is a double cluster, made up of two open clusters, which are located between Cassiopeia and the head of Perseus. Also known as "h and chi Persei", this rare double cluster is bright enough to be seen from a dark location without even binoculars.
Gemini
M35 - Gemini - Open Cluster
Gemini is one of the most prominent of the constellations of the zodiac. It is home to a number of impressive star clusters, and contains the twin stars Castor and Pollux. The only Messier object in Gemini is M35, an extremely attractive open cluster with gently curving rows of glittering stars. This spectacular, large open cluster contains about 200 stars. Shining at magnitude 5 it is reasonably easily located near the 3 "foot stars" of Gemini.
Taurus
M45 (Pleiades) - Taurus - Open Cluster
Taurus lies along the Milky Way and is home to many interesting astronomical features, most prominent of which are the Crab Nebula, Pleiades and Hyades clusters, and the bright orange star Aldebaran.
This is M45, or ‘Pleiades’, a relatively open cluster, surrounded by blue nebulosity illuminated by the light reflected from the nearby stars. It is often mistaken for the Little Dipper.
M1 (Crab Nebula) - Taurus - Supernova Remnant
Supernova remnants are nebulae that are formed when a star explodes. Gases from an exploding star form a rapidly expanding and slowly fading cloud, mixing with the interstellar matter which is swept up when the shell expands, forming supernova remnants.
This is M1, the ‘Crab Nebula’, the nearest, most famous and most spectacular known supernova remnant. When the parent of the Crab Nebula exploded it was seen by Chinese Imperial astronomers and records show that it was visible during the day for three weeks.
M1 (Crab Nebula) - Taurus - Supernova Remnant
At the centre of this supernova remnant lies a pulsar - a very dense, very small star composed almost entirely of neutrons, the remnants of the heart of the original star. Most of the white glow that fills the centre of the remnant is actually synchrotron radiation, produced by very fast moving electrons travelling in the strong magnetic fields in the nebula.
Ursa Major
The Big Bear, Ursa Major, is one of the most familiar constellations, containing the famous grouping of stars known as The Plough (also known as the Big Dipper). Because Ursa Major lies away from the bright Milky Way, many galaxies are visible in it. A galaxy is a huge system of stars, gas, dust, planets, and other interstellar matter that is held together by gravity and rotates around its own centre.
M81 is a large and beautiful spiral galaxy located in Ursa Major. It has a bright core with a stellar nucleus, and spiral arms. It is relatively close, at about 12 million light years and is estimated to be about 36,000 light years across.
M82 - Ursa Major – Galaxy
This is M82, a very unusual galaxy located in Ursa Major. It makes a spectacular pairing with the spiral galaxy M81 and is undergoing a violent episode of starburst activity as a result of its interaction with M81. A telltale sign of star formation are the huge lanes of dust that crisscross M82’s disk. More than 100 super star clusters, compact groupings of 100,00 stars, make up its glowing centre.
M97 - Ursa Major - Planetary Nebula
Planetary Nebulae have broad faces that looked somewhat like a planet through ancient telescopes. They are produced in the death throes of an old star shedding its outer layers and revealing a hot interior. They all have a blue star at the centre.
This is M97, the ‘Owl Nebula’, one of the more complex planetary nebulae. The central star is visible, along with the two darker regions that give the “owl” its large dark eyes.
M101 - Ursa Major – Galaxy
One of the grand spiral galaxies, M101 has several extremely luminous star forming regions in the outer spiral arms. Recent evidence suggests that gravitational interactions with nearby galaxies created waves of high mass and condensed gas, which continue to circle the galaxy. Hydrogen gas is falling into its disk at high speeds. Its immense gravity continues to distort smaller nearby galaxies. Its distance is estimated at about 24 million light years.
NGC2841 - Ursa Major – Galaxy
NGC2841 is a bright spiral galaxy with a long axis and bright nucleus. It sits at the claw of the Big Bear’s forefoot. Discovered in April 1999, interest in this galaxy was heightened in May of the same year, with the explosion of a supernova SN1999by nearby. It is a large spiral galaxy which lies at a distance of about 26 million light years.
Canes Venatici
Canes Venatici, the ‘Hunting Dogs’, is a small constellation visible in the northern hemisphere in spring and summer. While it has only two stars brighter than fifth magnitude, it is rich in galaxies.
M63, the ‘Sunflower Galaxy’, is a large, bright, elongated, spiral galaxy in Canes Venatici. The spiral arms are just visible as a grainy background, which brighten as they approach the centre. It forms a physical group with the whirlpool galaxy M51. It is about 36 million light years away.
M51 - Canes Venatici – Galaxy
M51, the ‘Whirlpool Galaxy’ is a bright spiral galaxy located in the Canes Venatici constellation, about 25 million light years away. To the north of M51, at the top of the image, a small companion galaxy is being torn apart by the gravitational pull of the main galaxy. It is the dominant member of a small group of galaxies and is one of the brightest and most picturesque galaxies in the sky.
Hercules
Hercules is the fifth largest constellation in the sky, but represents a relatively faint group of stars. Its central region, known as the ‘Keystone’, composes the brightest part of the constellation.
Near the ‘Keystone’ lies the ‘Great globular cluster in Hercules’ (M13), one of the finest to be found in the northern hemisphere. It is home to more than 100,000 stars, and towards its centre, stars are about 500 times more concentrated than in the solar neighbourhood.
M92 - Hercules - Globular Cluster
M92 is a splendid, medium-sized globular cluster that is visible to the naked eye,
lying on a line between eta and iota Herculis. Several hundred thousand stars are gravitationally bound into a spherical shape, which has a diameter of about 60 light years. Often overshadowed by the brighter M13, it contains one of few eclipsing binary pairs found of globular clusters.
Vulpecula
Vulpecula, ‘The Fox’, is a rather faint constellation, with most stars of fourth and fifth magnitude, and only one Bayer star. It was originally called ‘Vulpecula cum Anser’, ‘The Fox and Goose’.
Planetary nebula M27, the ‘Dumbbell Nebula’, is located in Vulpecula. Although it is one of the brightest and most impressive objects of its kind in the sky, it is so spread out that it appears quite faint. It was one of the first planetary nebula ever discovered, by Charles Messier in 1764.
Serpens
Serpens is officially one constellation, but is actually split into two distinct, disjointed areas of the sky, which are divided by the constellation Ophiuchus. They are named Serpens Caput and Serpens Cauda.
The spectacular ‘Eagle’ nebula and cluster (M16) is a great cloud of interstellar gas and dust, which has entered the brilliant process of star formation. The nebula shines in Serpens, roughly towards the Galactic centre, excited by the energy emitted from the newly formed stars. The nebula's distinctive red colour comes from its hydrogen gas emissions.
Hydra
M83 - Hydra – Galaxy
The dynamic ‘Southern Pinwheel’ is a magnificent spiral galaxy located in the constellation Hydra. The blue colour of the spiral arms is caused by the relatively large fraction of young blue stars there. Dark dust lanes follow the spiral structure and can be seen right into the central region. The nucleus is made up of an older stellar population and extends in a bar-like shape.
Lyra
Lyra is a small but bright northern constellation. The fifth-brightest star in the sky, ‘Vega’, radiates from the top of Lyra with a pure white colour.
Located midway in Lyra, the ‘Ring Nebula’, M57 is probably the most famous celestial band apart from the rings of Saturn. The core was formed when a star bigger than the sun collapsed inwards, forming a white dwarf smaller than the Earth. The gas nebula was formed when the outer layers of the star were ejected into space, then ionised by the hot radiation.
Coma Berenices
Coma Berenices, meaning ‘Berenice’s Hair’ is a faint constellation of the northern hemisphere, to the north of Virgo, between Bootes and Leo.
The ‘Black Eye’ M64 galaxy (also known as the Sleeping Beauty galaxy) is located in Coma Berenices. The noticeable dark lane in the central region is a prominent dust feature obscuring the stars behind. M64 has two counter-rotating systems of stars and gas in its disk. New stars can be seen as blue dots outside the nucleus.
Leo
Leo is the fifth constellation of the zodiac. It is a compact constellation and is fairly easy to identify due to the fact that it looks quite like its ancient mythological character.
M66 is a spiral galaxy located in the Leo triplet of galaxies along with M65 and NGC3628. M66 has a well developed central bulge. Its spiral arms are deformed, distorted and displaced above the plane of the galaxy.
Pisces
M74 - Pisces – Galaxy
Pisces, the twelfth constellation of the zodiac, is a faint constellation in the equatorial region of the sky. It contains few bright stars, and only one important object, the face-on spiral galaxy M74.
M74 is about the same size as the Milky Way, and its magnificent spiral arms are about 1000 light years across. Dotted among the spiral arms are clusters of blue young stars, and the pink glow of diffuse gaseous nebulae.
Virgo
M87 - Virgo - Galaxy
Virgo is the second largest constellation in the sky. The outstanding Virgo Cluster of galaxies lies at the heart of Virgo, and extends into the constellation Coma.
This giant elliptical galaxy M87, also called Virgo A, lies in the heart of the Virgo Cluster. It is about 120 000 light years across and contains an estimated 2.7 trillion stars. M87 is famous for its spectacular jet, about 7-8 light years long.
M104 (Sombrero Galaxy) - Virgo – Galaxy
Called the Sombrero Galaxy, M104 is located in the Virgo constellation. Seen from 6 degrees south of its equatorial plane, its rim of thick obscuring dust gives the galaxy its common name. It has an unusual bulge in the centre, and its well-definedspiral arms can be seen. The extended halo, which surrounds the galaxy, is where orbiting globular star clusters are found.
Pegasus
NGC7331 - Pegasus – Galaxy
Pegasus, the winged horse, is one of the large constellations of the northern hemisphere. Although it has no really bright stars, it is easy to spot because three of its brightest stars form part of the Great Square of Pegasus.
NGC7331, a large, bright, spiral galaxy, can be found near the north-west star of Pegasus’ square. It is about 30 000 light years across and contains the equivalent of about 140 billion stars.
Andromeda
NGC891 - Andromeda – Galaxy
Andromeda is a large constellation of the northern hemisphere. It extends from the constellation Perseus to the north-east corner of the great square of the constellation Pegasus.
NGC891, a barred spiral galaxy, presents itself to Earth nearly edge-on. Faint in the night sky, a dark dust rim bisects it.
M31 - Andromeda – Galaxy
The Andromeda Galaxy, our nearest spiral galaxy, is also known as M31, and is part of our local group. Visible to the naked eye, it is easily studied. Many of the features found in the Milky Way are also found in Andromeda. Because areas of our Galaxy are obscured by galactic dust, we are able to learn more about them by studying Andromeda.
NGC7293 (Helix Nebula)
NGC7293, the ‘Helix Nebula’ located near Aquarius, is the closest of all planetary nebulae. It lies only 450 light years away, offering a dramatic snapshot of a brief final evolutionary stage in the life of a solar-type star. It is also one of the largest planetary nebulae known. This photo shows part of the faint outer loop of the nebula, a faint line near the top left corner.
Triangulum
M33 (Triangulum Galaxy) - Triangulum - Galaxy
Triangulum, the ‘Triangle’, is a distinctively shaped constellation located at the south-east edge of Andromeda.
Part of our local group, the ‘Triangulum Galaxy’ M33 is a spiral galaxy located within the constellation. When compared to Andromeda, it appears to be quite small, but in fact it is of average size, with an estimated diameter of at least 60 000 light years, with between 10 and 40 billion solar masses.
Cancer
M44 - Cancer - Open Cluster
Cancer, ‘The Crab’, is fifth of the constellations of the zodiac. Although small and faint, it is an important constellation. It contains faint galaxies, bright open clusters, and numerous double and multiple stars.
M44 is known as the ‘Beehive’ or ‘Praesepe’, a prominent open cluster located in the constellation Cancer. It is one of the few open clusters easily visible to the naked eye and has been known since prehistoric times.
More than 200 of the 350 stars in the cluster area have been confirmed as members. The Beehive Cluster lies about 580 light-years away, and is about 10 light-years across.
Stars with planets around them
Upsilon Andromedae - 3 planets
Upsilon Andromedae is notable as being the first planetary system discovered orbiting a normal star other than our Sun. The three planets were found using a Doppler technique developed to search nearby stars for planetary systems. Upsilon can be seen with the naked eye by looking in the direction of the constellation of Andromeda. At 44 light years away, Upsilon Andromedae is a little larger and just slightly hotter than our Sun.
rho(1) Cancri - 2 planets
rho(1) Cancri system is located about 40.9 light-years from the Sun. It lies in the north-eastern part of the constellation Cancer, the Crab. In 1996, astronomers announced the discovery of a Jupiter-like planet around this Sun-like star with indications of an even larger planet in an outer orbit. The star has a mature red giant companion, and is slightly cooler than the sun, at about 5600K.
Content last updated: 29/04/2008
