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some read an uplifting story, and others may watch an inspiring tvnovellas.info I have quotes placed anywhere that I can see. ATLAS OF THE UNIVERSE. Astronomy through the Ages. Astronomy is certainly the oldest of all the sciences. Our remote cave-dwelling. PDF | Cosmic Atlas is a software program produced at the Denver Museum of Nature & Science to generate real-time digital content for the.
There are nine main maps on this web page, each one approximately ten times the scale of the previous one. The first map shows the nearest stars and then the other maps slowly expand out until we have reached the scale of the entire visible universe. This map shows all of the stellar systems that lie within This map shows this tiny section of our galaxy that surrounds our Sun. It is depicted here showing the millions of stars interspersed with clouds of interstellar gas.
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Are you sure you want to Yes No. Be the first to like this. No Downloads. Views Total views. Actions Shares. Embeds 0 No embeds. No notes for slide. Book Details Author: Roy A. Gallant Pages: Hardcover Brand: Notice Message: Trying to get property of non-object Filename: If you want to download this book, click link in the next page 5. Because the crust is shifting over the confined to the areas where and have now drifted apart.
When plates are moving apart, hot mantle Other volcanoes, such as Vesuvius in Italy, are cone- material rises up between them to form new oceanic crust. The magma forces its way up through a vent, and When plates collide, one plate may be forced beneath if this vent is blocked the pressure may build up until another — a process known as subduction — or they may there is a violent explosion — as happened in AD 79, when buckle and force up mountain ranges.
Regions where the Roman cities of Pompeii and Herculaneum were the tectonic plates meet are subject to earthquakes and destroyed. There are constant eruptions upon Io, one of the Several types of waves are set up in the globe. Upper mantle Crust Volcanoes Volcanoes form where tectonic plates Magma may also find its way to the Transition zone Outer core meet.
Pockets of magma force themselves surface via side vents. A volcano may be up from the mantle through weak inactive for a considerable time, Lower mantle Inner core points in the crust. The molten allowing the magma to solidify magma may bubble inside near the surface.
Huge pressure the crater or give off can then build up beneath it, clouds of ash and gas. Ash and gas cloud Crater Neck or pipe Side vent.
Magma chamber. Rock strata. The crust is only on average 10 km 6 miles thick beneath the oceans and 50 km 30 miles thick beneath the land.
Below is the km-thick miles mantle of hot, plastic rock. Inside that is an outer liquid core, km miles thick, with a solid core inside it, km miles in diameter. Primary P Waves. Secondary S Waves. The epicentre P waves are compression crust on either side is being is the point on the surface waves that travel through forced to move in different directly above the focus solid and fluid alike.
S waves directions. The focus, where where the damage is are transverse waves that the fault gives, can be up usually most severe. Sur- by Dominic Cantin. This is because of the presence of ozone, the maximum of its cycle of molecule of which is made up of three oxygen atoms activity, there were several instead of the usual two; ozone is warmed by short-wave exceptionally brilliant radiations from the Sun.
However, the rise in temperature aurorae. Scientifically, temperature is defined by the rate at which the atoms and molecules fly around; the greater the speeds, the higher the tempera- ture. Whether it is being damaged by our own activities is a matter for debate, but the situation needs to be watched. On the sunward China, as has often been claimed! The outlines of the seas ble. In the ionosphere we find the lovely noctilucent side of the Earth, the solar and continents show up clearly, and there are also clouds clouds, which are quite unlike ordinary clouds, and may wind compresses the in the atmosphere, some of which cover wide areas.
The ionosphere is often divided On the opposite side, whole weather systems instead of having to rely upon into the mesosphere, up to 80 kilometres 50 miles , and interaction with the solar reports from scattered stations. The atmosphere is made the thermosphere, up to kilometres miles.
There is also the orbit of the Moon. The lowest of Aurorae, or polar lights — aurora borealis in the north- which the solar wind these, the troposphere, extends upwards for about 8 kilo- ern hemisphere, aurora australis in the southern — are cannot easily flow, is the metres 5 miles out to more than 17 kilometres over 10 also found in the ionosphere; the usual limits are from magnetopause; a bow shock miles — it is deepest over the equator.
It is here that to kilometres 60 to miles , though these is produced in the solar wind we find clouds and weather. The temperature falls with limits may sometimes be exceeded. Aurorae are seen in preceding the magnetopause increasing height, and at the top of the layer has dropped various forms: They change very rapidly, and can be.
They are due to electrified particles from space, mainly originating in the Sun, which collide with atoms and molecules in the upper atmosphere and make them glow. Because the particles are electrically charged, they tend to cascade down towards the magnetic poles, so that aurorae are best seen from high latitudes.
They are very common in places such as Alaska, northern Norway, northern Scotland and Antarctica, but are much rarer from lower latitudes such as those of southern England, and from the equator they are hardly ever seen. When there are violent disturbances in the Sun, producing high-speed particles, the ovals broaden and expand, producing dis- plays further from the main regions. Aurorae have been known for many centuries. The Roman emperor Tiberius, who reigned from AD 14 to 37, once dispatched his fire- engines to the port of Ostia because a brilliant red aurora led him to believe that the whole town was ablaze.
The Earth has a strong magnetic field. The region over which this field is dominant is called the magneto- sphere; it is shaped rather like a tear-drop, with its tail pointing away from the Sun. On the sunward side of the Earth, it extends to about 65, kilometres 40, miles , but on the night side it spreads out much further. Inside the magnetosphere there are two zones of strong radiation; they were detected by the first successful American satellite, Explorer 1 of February , and are known as the Van Allen zones, in honour of the scientist who designed the equipment.
There are two main zones, one with its lower limit at just under kilometres miles and the other reaching out to 37, kilo- metres 23, miles. At least it is conspicuous; their origin certain that the field is due to currents in the iron-rich is uncertain, but they may liquid core.
Incidentally, it is worth noting that the Moon be due to water droplets and Venus have no detectable magnetic fields, and that of condensing on meteoritic Mars is extremely weak, though that of Mercury is particles.
This photograph stronger than might have been expected.
Magnetically, was taken from Alaska in Earth is quite unlike the other inner planets. January A. In a way this is true. We are by no means certain about the origin of the The orbital period is The attractive old theory according to which it with the phases, or apparent changes of shape, from new to simply broke away from the Earth, leaving the hollow full.
There is no mystery ed. It may be that the Earth and the Moon were formed about this; it is due to light reflected on to the Moon from together from the solar nebula, but there is increasing sup- the Earth, and is therefore known as earthshine.
It can port for the idea that the origin of the Moon was due to a be quite conspicuous. This is due to tidal friction over the ages. However, these effects are very slight.
There are The Waning Moon 6. In the Serenitatis with the great Tycho and Copernicus. Crescent Moon 2 , Mare chain of craters near the Although the craters are are so prominent that crater More of the dark maria Crisium is prominent central meridian. Since well illuminated and readily identification becomes which were once thought between the eastern the Sun is still low over the identifiable, their spectacular difficult.
The lunar maria to be seas are illuminated. Distance from Earth, centre to centre: The Moon has a crust, a mantle and a core.
There is a max. The atmosphere seems to be in the form of a colli- Albedo 0. When they act at can be no more than about 30 tons. The density is of the Diameter The Half Moon, Last Quarter 7. The rays are less striking; shadows inside the large craters are increasing. The Old Moon 8 occurs just before the New, seen in the dawn sky.
Earthshine may often be seen. Features of the Moon Tamount he Moon is much the most spectacular object in the sky to the user of a small telescope. A crater which is Most of the major maria form a connected system. It appears elongated in a north—south direction, but The most obvious features are the wide dark plains this is because of the effect of foreshortening; the known as seas or maria.
Part of the known that there is no water in them and never has the east—west diameter is kilometres miles. Mare Imbrium; the craters been! The Storms. They are of various types. Some, such as the which range from vast enclosures such as Bailly, low-walled formation with Mare Imbrium, are essentially circular in outline, with kilometres miles in diameter, down to tiny pits.
No two interior craterlets is mountainous borders; the diameter of the Mare Imbrium is part of the Moon is free from them; they cluster thickly Cassini.
The Alpine Valley kilometres miles. Other seas, such as the vast in the uplands, but are also to be found on the floors of can be seen cutting through Oceanus Procellarum, are irregular and patchy, so that the maria and on the flanks and crests of mountains.
There They break into each other, sometimes distorting each top of the picture. Fracastorius, at the edge of the Mare Nectaris, is a good example of this. Riccioli, a Jesuit astronomer who drew a lunar map in , named the main craters after various person- alities, usually scientists. His system has been followed up to the present time, though it has been modified and extended, and later astronomers such as Newton have come off second-best.
Some unexpected names are found. Julius Caesar has his own crater, though this was for his association with calendar reform rather than his military prowess.
Central peaks, and groups of peaks, are common, and the walls may be massive and terraced. Yet in profile a crater is not in the least like a steep-sided mine-shaft. The walls rise to only a modest height above the outer surface, while the floor is sunken; the central peaks never rise as high as the outer ramparts, so that in theory a lid could be dropped over the crater! Some formations, such as Plato in the region of the Alps and Grimaldi near the western limb, have floors dark enough to make them identifiable under any conditions of illumination; Aristarchus, in the Oceanus Procellarum, is only 37 kilometres 23 miles across, but has walls and central peak so brilliant that when lit only by earthshine it has sometimes been mistaken for a volcano in eruption.
One crater, Wargentin in the south-west limb area, has been filled with lava to its brim, so that it has taken on the form of a plateau. It is almost 90 kilometres 55 miles across. The most striking of all the craters are Tycho, in the southern uplands, and Copernicus in the Mare Nubium. Under high light they are seen to be the centres of systems of bright rays, which spread out for hundreds of kilo- metres. They are surface features, casting no shadows, so that they are well seen only when the Sun is reasonably high over them; near Full Moon they are so prominent that they drown most other features.
Interestingly, the Tycho rays do not come from the centre of the crater, but are tangential to the walls. There are many other minor ray- centres, such as Kepler in the Oceanus Procellarum and Anaxagoras in the north polar area. The main mountain ranges form the borders of the regular maria; thus the Mare Imbrium is bordered by.
Isolated peaks and hills abound, and there are also domes, which are low swellings often crowned by summit craterlets. One feature of special interest is the Straight Wall, in the Mare Nubium — which is not straight, and is not a wall! It is by no means sheer, and the gradient seems to be no more than 40 degrees. In the future it will no doubt become a lunar tourist attraction Valleys are found here and there, notably the great gash cutting through the Alps. There are also rills — alternatively known as rilles or clefts — which are crack-like collapse features.
Some of these, too, prove to be crater-chains either wholly or in part. The most celebrated rills are those of Hyginus and Ariadaeus, in the region of the Mare Vaporum, but there are intricate rill-systems on the floors of some of the large craters, such as Gassendi, near the northern boundary of magma pouring out from below and flooding the basins.
It has been claimed that the ray-craters Tycho and ray-centres of the Moon. Many of the maria are crossed by ridges, which are Copernicus may be no more than a thousand million years Eratosthenes, smaller but low, snaking elevations of considerable length. Ridges on old, though even this is ancient by terrestrial standards.
There followed widespread vulcanism, with essentially changeless. Ptolemaeus is to the top of the picture, at the centre; below it comes Alphonsus, with a reduced central peak and dark patches on its floor; below Alphonsus is Arzachel, smaller but with higher walls and a central peak. The walled plain Albategnius lies to the left of Ptolemaeus. Lunar Landscapes Lalways unar photographs taken with even small telescopes can show a surprising amount of detail, and there appears to be something new to see.
Two of the best-known rills are shown here. The Hyginus Rill, near the centre, is actually a crater-chain; the largest feature, Hyginus, is 6 km 4 miles in diameter. To the right are the dark-floored Boscovich and Julius Caesar. Thebit, on the edge of the Mare Nubium, is 60 km 37 miles in diameter. It is interrupted by a smaller crater, Thebit A, which is in turn broken by the smaller Thebit F — demonstrating the usual arrangement of lunar cratering.
To the left of Thebit is the fault misnamed the Straight Wall; to the left of the Wall is the well-formed, km mile crater Birt, associated with a rill which ends in a craterlet. The Far Side of the Moon 4 X LTheookseepositions at the Moon, even with the naked eye, and you will the obvious features such as the principal maria. All side. However, the rate of between the two hemispheres. After a quarter of its limbs. In many from perigee it has moved Finally there is a diurnal or daily libration, because we are ways Tsiolkovskii seems to be a sort of link between a slightly faster than its mean observing from the surface, not the centre of the globe.
As seen from carried in and out of view. They are so foreshortened that Many of the familiar types of features are seen on the Earth, X lies slightly east of it is often difficult to distinguish between a crater and far side, and the distribution of the craters is equally non- the apparent centre of the a ridge, and before our maps of them were very random; when one formation breaks into another, it is disk, and a small portion imperfect.
About the permanently hidden regions nothing always the smaller crater which is the intruder. Valleys, of the far side has come definite was known. It was reasonable to assume that they peaks and rays systems exist. Though the Moon has no into view in the west. After were basically similar to the familiar areas — though some overall magnetic field that we can detect, there are regions a further quarter-month the strange ideas had been put forward from time to time.
The of localized magnetism here and there; one of these lies Moon has reached position last-century Danish astronomer Andreas Hansen once near the rather irregular far-side crater Van de Graaff. A further round to the far side, which might well be inhabited! The magnetic field which has now died away. It went right round the Moon, taking pictures of thought to be a mountain range which was promptly west, so that an area beyond the far side and later sending them back by television named in honour of the Soviet Union.
Alas, it was later the mean eastern limb is techniques. The pictures are very blurred and lacking found that the feature is nothing more than a surface ray, uncovered.
At the end of one in detail, but they were good enough to show that, as and the Soviet Mountains were tactfully deleted from orbit the Moon has arrived expected, the far side is just as barren and just as crater- the maps.
However, it was surely right to name the back at 1, and X is once scarred as the areas we have always known. Its floor contains several smaller craters. The wall is broken top right-hand corner by Birkeland, a well-formed crater with a prominent central peak. It is km structure. The darkness lunar feature, falling 4 Boltzmann 55 S W miles in diameter, is caused by lava; in fact somewhere between a 5 Brianchon 77 N 90 W with terraced walls and a Tsiolkovskii seems to be crater and a mare, or sea.
Missions to the Moon Tandhespacecraft. Russians took the lead in exploring the Moon with Their Luniks contacted the Moon in , they were also the first to make a controlled landing By Christmas the crew of Apollo 8 were able to go round the Moon, paving the way for a landing. Apollo 9 was an Earth-orbiter, used to test the lunar with an automatic probe. Millions of people on Earth watched the Moon, enabling the Earth. The gap between our world and greater areas. Astronaut when it became painfully clear that their rockets were not another had at last been bridged.
Irwin stands by the Rover, sufficiently reliable. The two astro- with one of the peaks definitely over. The electrically vehicles crash-landed on the Moon, sending back data and Experimental Package , which included various instru- powered Rovers performed pictures before being destroyed; the Surveyors made soft ments — for example a seismometer, to detect possible faultlessly.
Once their work was on the Moon are notoriously maps of virtually the entire surface. Meanwhile, the Apollo completed interrupted only briefly by a telephone call difficult to estimate. The lower part of the lunar module was used as a launching pad, and was left behind, where it will remain until it is collected and removed to a lunar museum.
The return journey to Earth was flawless. Apollo 12 November was also a success; astro- nauts Conrad and Bean were even able to walk over to an old Surveyor probe, which had been on the Moon ever since , and bring parts of it home. Apollo 13 April was a near-disaster; there was an explosion during the outward journey, and the lunar landing had to be abandoned. One of the Apollo 17 astronauts, Dr Harrison Schmitt, was a pro- fessional geologist who had been given training specially for the mission.
The Apollo programme has increased our knowledge of the Moon beyond all recognition — and yet in a way it. Mare Fecunditatis can be seen in the background. The Rover performed faultlessly. The Lunar Module was designed to make a landing on the Moon and return the astronauts to orbit. The upper section has one ascent engine only, and there can be no second chance. The photograph was taken from the orbiting Command Module.
The various ALSEPs continued operating for some years, until they were eventually switched off mainly on financial grounds. No men have been to the Moon since , though there have been a few unmanned missions. In the Japanese probe Hiten crashed on the Moon near the crater Furnerius, and images were also sent back by the Galileo probe en route to Jupiter.
We may hope for the establish- ment of a Lunar Base and a Lunar Observatory in the fore- seeable future. To quote Eugene Cernan, commander of Apollo 17, when I talked with him:. We went to the Moon not initially for scientific purposes, but for national and political ones which was just as well, because it enabled us to get the job done!
There will be others who will follow in our steps. The Lunar Rover is well shown. This picture was taken from Apollo 17, the last manned lunar mission. It shows the crescent Earth rising over the limb of the Moon; when the photograph was taken, Apollo 17 was in lunar orbit. During one of the Moon walks, Dr Schmitt, the geologist, suddenly called attention to what seemed to be orange soil inside a small crater, unofficially named Shorty.
The latest American lunar probe was paid for by the Department of Defense. It weighed kg lb , and carried an array of sensors. Tlunar he mission to the Moon, Clementine, was named after an old American mining song — because, after the part of its programme, the probe was scheduled to go on 3 January , and carried out an extensive mapping survey. On 31 July it was deliberately crashed into a polar crater, in the hope that water might be detected in the on to an asteroid, and it has been suggested that in the debris, but no signs of water were found and the idea of future it may be possible to carry out mining operations on lunar ice has been generally abandoned.
The military authorities on 24 January from were anxious to test instruments and techniques capable the Vandenburg Air Force of locating hostile ballistic missiles, and the only way to Base, and put into a circular circumvent the strict regulations about this sort of activity orbit round the Earth. It was to go to the Moon. Therefore, the Department could departed for lunar orbit on test its anti-ballistic missile system and do some useful 21 February, and spent two scientific work as well.
It weighed kilograms lb than the rest of the surface. After completing this part of its mission several manoeuvres were carried out, and Clementine entered lunar orbit on 21 February Clementine surveyed the whole of the Moon.
Many gravity measurements were made, and superb images obtained; the inclined orbit meant that the polar regions could be mapped more accurately than ever before. For example, there were detailed views of the vast South Pole—Aitken Basin which is kilometres miles in diameter and 12 kilometres 7 miles deep.
There was also the Mendel-Rydberg Basin, kilometres miles across, which is less prominent because it lies under a thick blanket of debris from the adjacent Mare Orientale.
It was claimed that Clementine had detected indica- tions of ice inside some of the polar craters, whose floors are always in shadow — but ice did not seem at all probable on a world such as the Moon. Clementine left lunar orbit on 3 May ; it had been hoped to rendezvous with a small asteroid, Geographos, but a programming error ruled this out.
The next lunar probe, Prospector, was launched. The bright blue area in this false-colour image is the Aristarchus crater, which is 42 km 26 miles in diameter. Pyroclastics fragmental volcanic ejecta , which appear reddish here, surround the crater. The pyroclastics probably formed from gas-driven eruptions that leave deposits rich in glass droplets frozen from the spray of molten lava.
The spacecraft was deliberately crashed on to the Moon in the search for ice. The Moon: The whole the Mare Serenitatis and Mare Crisium are included, of the Mare Tranquillitatis and the darkish Mare of Hyginus — which is curved, and is mainly a craterlet-chain.
Another complex rill system is associated with Triesnecker and Ukert. All these features are visible with a small telescope Vaporum, with parts of the Mare Frigoris and Mare under good conditions. There are also some small seas close to the Aristillus This makes up a group together with Archimedes limb Smythii, Marginis, Humboldtianum which are which is shown on the map of the Second Quadrant and never easy to observe because they are so foreshortened.
All three are very prominent. Under high illum- There are also large walled plains close to the limb, such ination Autolycus is also seen to be the centre of a minor ray- as Neper and Gauss. In the south, the Mare Serenitatis is bordered by the Aristoteles This and Eudoxus form a prominent pair of walled Haemus Mountains, which rise to metres feet. Aristoteles has walls rising to metres 11, feet The Alps run along the southern border of the Mare above the floor.
Atlas and Hercules form another imposing Frigoris, and here we find the magnificent Alpine Valley, pair.
Atlas has complex floor-detail, while inside Hercules there which is kilometres 80 miles long and is much is one very bright crater. Mont Blanc, in the Alps, rises to seems to belong to the Tycho system. There are several major rill systems with rills. The Apollo 11 phenomenon also found elsewhere, as with Steinheil and Watt astronauts landed in the Mare Tranquillitatis, not far from in the Fourth Quadrant.
Maskelyne, and Apollo 17 came down in the area of Cleomedes A magnificent enclosure north of Mare Crisium. Littrow and the clumps of hills which are called the The wall is interrupted by one very deep crater, Tralles.
Taurus Mountains. Dionysius One of several very brilliant small craterlets in the rough region between Mare Tranquillitatis and Mare Vaporum; Agrippa A fine crater with a central peak and terraced walls. It forms a notable pair with its slightly smaller neighbour Endymion A large enclosure with a darkish floor. It joins the Godin. Arago A well-formed crater, with the smaller, bright Manners Gioja The north polar crater — obviously not easy to examine to the south-east.
Close to Arago is a whole collection of from Earth. It is well formed, and intrudes into a larger but domes — some of the finest on the Moon; many of them have low-walled formation. Julius Caesar This and Boscovich are low-walled, irregular Archytas The most prominent crater on the irregular Mare formations, notable because of their very dark floors.
It has bright walls and a central peak. Le Monnier A fine example of a bay, leading off the Mare Ariadaeus A small crater associated with a major rill system. Only a few mounds of its seaward wall remain. It was once suspected of having various branches, one of which connects the system with that changed from a craterlet into a white spot at some time between and , but this is certainly untrue. So too is Menelaus, in the Haemus Mountains.
It has high, Aristoteles 97 50 18 Macrobius 68 21 46 Atlas 69 47 44 Main 48 81 9 terraced walls; the central structure takes the form of a twin Autolycus 36 31 1 Manilius 36 15 9 crater. Bessel 19 22 18 Manners 16 5 20 Bond, W. Cauchy 13 10 39 Neper 7 83 Proclus One of the most brilliant craters on the Moon. It is Cayley 13 4 15 Peirce 19 18 53 Challis 56 78 9 Picard 34 15 55 the centre of an asymmetrical ray system; two rays border the Chacornac 48 30 32 Plana 39 42 28 Palus Somnii, which has a curiously distinctive tone.
Cleomedes 27 55 Plinius 48 15 24 Condorcet 72 12 70 Posidonius 96 32 30 Sabine This and Ritter make up a pair of almost perfect twins — De la Rue 67 56 Proclus 29 16 47 one of many such pairs on the Moon. There is a cen- Dionysius 19 3 17 Ritter 32 2 19 Endymion 55 55 Sabine 31 2 20 tral mountain with a summit pit, and a complete inner ring on Eudoxus 64 44 16 Sulpicius Gallus 13 20 12 the floor.
It has bright walls, with a darkish floor and a central peak. West of it is Stadius, a typical ghost ring; it has a diameter of 70 kilometres 44 miles , but its small part of the Sinus Medii and a section of the narrow, walls have been so reduced that they are barely traceable.
The Sinus Iridum, leading off Probably the walls can be nowhere more than about 10 metres the Mare Imbrium, is perhaps the most beautiful object 33 feet high. Hevelius has a which border it. There are two prominent capes, Laplace convex floor and a low central peak; a system of rills lies on and Heraclides; the seaward wall of the bay has been the floor.
West of Hevelius is Hedin, visible only under condi- virtually levelled. The Apennines make up the most conspicuous moun- Kepler A bright crater, and the centre of a major ray-system. Its tain range on the Moon; with the lower Carpathians in southern neighbour, Encke, is of about the same size, but is the south, they make up much of the border of the Mare much less bright and has no comparable ray-system. The Straight Range, in the northern part of Le Verrier This and Helicon make up a prominent crater-pair in the Mare, is made up of a remarkable line of peaks rising the Mare Imbrium, near Sinus Iridum.
Unusual coloration effects have been reported here. The Harbinger Mountains, in the Aristarchus area, Plato A large walled plain with fairly low walls, and an iron- are made up of irregular clumps of hills. Isolated peaks grey floor which makes it readily identifiable under any con- include Pico and Piton, in the Mare Imbrium.
Pico is very ditions of illumination. Plato is perfectly circular, though as seen from Earth was once called Newton, though the name has now been it is foreshortened into an oval. Further along the limb, to the south, is the smaller, Anaxagoras A well-formed crater with high walls and central similar but still very imposing Xenophanes.
It is very bright, and is the centre of a major ray-system, Timocharis A well-marked formation with a central crater a so that it is easy to find under all conditions of illumination. Timocharis is the Archimedes One of the best-known of all walled plains; regu- centre of a rather obscure system of rays. It forms a splendid trio with Aristillus and Autolycus, which lie in the First Quadrant.
Its brilliant walls Crater Diameter, Lat. Close by is Herodotus, of similar size Anaximander 87 66 48 Hortensius 16 6 28 but normal brightness. The total length is kilometres miles , Bessarion 15 14 37 Lambert 29 26 21 and the maximum depth metres feet. It is low-walled and broken, and one of several Encke 32 5 37 Philolaus 74 75 33 formations of similar type in the far north; others are Babbage, Epigenes 52 73 4 Piazzi Smyth 10 42 3 South and John Herschel.
Einstein 18 86 Plato 97 51 9 Carlini One of a number of small, bright-walled craterlets in the Eratosthenes 61 15 11 Pythagoras 65 65 Mare Imbrium. Einstein has a large central Harpalus 52 53 43 Struve 25 75 Helicon 29 40 23 Timaeus 34 63 1 crater.
It is visible only under conditions of favourable libration Herodotus 37 23 50 Timocharis 35 27 13 and is not shown on the map — as when I discovered it in Herschel, Caroline 13 34 31 Ulugh Beigh 70 32 85 , using my centimetre inch reflector. Herschel, John 62 41 Xenophanes 57 77 Eratosthenes A magnificent crater, with massive walls and Hevelius 2 67 a high central peak; it marks one end of the Apennines, and.
Htogether ighlands occupy a large part of the Third Quadrant, though part of the huge Mare Nubium is included with the whole of the Mare Humorum. There are one large crater, Ammonius; Alphonsus has a central peak and a system of rills on its floor; Arzachel is smaller, but with higher walls and a more developed central peak.
Several TLP some high mountains on the limb, and a very small part of have been seen in Alphonsus. Nearby is Alpetragius, with the Mare Orientale can be seen under really favourable regular walls and a central peak crowned by a craterlet. The other members are Walter, which Of course the most prominent crater is Tycho, whose rays has fairly regular walls, and Regiomontanus, which gives the dominate the entire surface around the time of Full Moon.
The Wall. The most important rill systems are those of Sirsalis, walls are rather low and irregular; the floor contains some Ramsden, Hippalus and Mersenius. Schiller A compound formation, produced by the fusion of two Bailly One of the largest walled plains on the Moon, but unfor- old rings.
Bullialdus A particularly fine crater, with massive walls and cen- Tycho The great ray-crater. Its bright walls make it prominent tral peak. It is not unlike Copernicus in structure, though it even in low illumination. Near Full Moon it is clear the rays is not a ray-centre. Capuanus A well-formed crater, with a darkish floor upon which there is a whole collection of domes. The north-western walls are broken by a km km large crater, Porter, and there is a chain of craters arranged Agatharchides 48 20 31 Lalande 24 4 8 in an arc across the floor.
Near the terminator, Clavius can be Alpetragius 43 16 4 Lassell 23 16 8 seen with the naked eye. Apollo 14 landed near here. There is a rill-system on the Byrgius 64 25 65 Nasireddin 48 41 0 floor, and TLP have been seen here. North of Gassendi is a Campanus 38 28 28 Newton 78 20 large bay, Letronne. Capuanus 56 34 26 Nicollet 15 22 12 Grimaldi The darkest formation on the Moon.
Adjoining it is Riccioli, which is less regular but has one Cysatus 47 66 7 Piazzi 90 36 68 patch on its floor almost as dark as any part of Grimaldi. Damoiseau 35 5 61 Pictet 48 43 7 Hippalus A fine bay in the Mare Humorum, associated with Darwin 20 69 Pitatus 86 30 14 a system of rills.
Like another similar bay, Doppelmayer, Davy 32 12 8 Ptolemaeus 9 3 Hippalus has the remnant of a central-peak. Near it lies a large dome with a summit craterlet. Flammarion 72 3 4 Rocca 97 15 72 Maginus A very large formation with irregular walls; other Flamsteed 19 5 44 Saussure 50 43 4 large walled plains of the same type in the area are Fra Mauro 81 6 17 Scheiner 60 28 Longomontanus and Wilhelm I.
Grimaldi 6 68 Segner 74 59 48 Mercator This and Campanus form a notable pair. They are Gruemberger 87 68 10 Short 70 76 5 alike in form and shape, but Mercator has the darker floor. Guericke 53 12 14 Sirsalis 32 13 60 Mersenius A prominent walled plain closely west of the Mare Hainzel 97 41 34 Thebit 60 22 4 Humorum, associated with a fine system of rills. Hansteen 36 11 52 Tycho 84 43 11 Heinsius 72 39 18 Vieta 52 29 57 Moretus A very deep formation in the southern uplands, with a Hell 31 32 8 Vitello 38 30 38 particularly fine central peak.
Herigonius 16 13 34 Walter 33 1 Newton One of the deepest formations on the Moon, but Herschel 45 6 2 Wargentin 89 50 60 never well seen because it is so close to the limb. It has a dark floor and a low central peak.
Kies 42 26 23 Wilson 74 69 33 A pass connects it with the neighbour Hesiodus, which is Kircher 74 67 45 Wurzelbauer 80 34 16 associated with a long rill extending south-westwards.
Klaproth 70 26 Zucchius 63 61 50 Ptolemaeus The largest member of the most imposing line of Lagrange 33 72 Zupus 26 17 52 walled plains on the Moon. Ptolemaeus has a flattish floor with. A fairly regular crater, making up a group with less perfect Gutenberg and deformed Magelhaens.
Hipparchus A very large enclosure not far from Ptolemaeus. There are some large ruined enclosures such as It is very broken, but under low light is still impressive. It Janssen and Hipparchus, and three imposing formations adjoins Albategnius, which is rather better preserved and in a group — Theophilus, Cyrillus and Catharina. We also has a low central peak.
There are two crater- well seen — though the space probe pictures show that it has valleys, those of Rheita and Reichenbach, plus the fasci- considerable floor detail, including a system of rills.
It adjoins nating little Messier, which was once wrongly suspected the smaller formation of Phillips, which is of similar type. The feature once called the Janssen A vast enclosure, but in a very poor state of repair. Altai Mountain range is now known as the Altai Scarp, Its walls are broken in the north by Fabricius and in the which is certainly a better name for it; it is concentric south by the bright-walled Lockyer.
It has high, from the prominent crater Piccolomini. Near full moon, Alfraganus A small, very bright crater; minor ray-centre. Langrenus appears as a bright patch. Disturbances inside Aliacensis This crater and its neighbour Werner are very regu- Langrenus have been photographed by A. Dollfus — the best lar.
There are several rather similar crater-pairs in the Fourth proof to date of the reality of lunar transient phenomena. Quadrant; others are Abenezra-Azophi and Almanon-Abulfeda. It is crossed by a ridge.
Adjoins Isidorus, of similar size. Messier This and its twin, Messier A formerly known as W. Fracastorius A great bay opening out of the Mare Nectaris. Pickering lie on the Mare Foecunditatis. They show Its seaward wall has been virtually destroyed. Between it remarkable changes in appearance over a lunation, though and Theophilus is a smaller bay, Beaumont. Its walls rise to over metres 11, feet in Airy 35 18 6 Licetus 74 47 6 places; the slightly convex floor contains a complex central Alfraganus 19 6 19 Lilius 52 54 6 mountain group, and a prominent rill runs from the centre Aliacensis 84 31 5 Lindenau 56 32 25 to the south-west wall.
Oddly enough, Petavius is none too Apianus 63 27 8 Lockyer 48 46 37 Azophi 43 22 13 Maclaurin 45 2 68 easy to identify at full moon. In fact, it is a crater- Beaumont 48 18 29 Magelhaens 40 12 44 chain — several major rings which have coalesced.
Blanchinus 53 25 3 Manzinus 90 68 25 Piccolomini The prominent, high-walled crater at the arc of Boguslawsky 97 75 45 Marinus 48 40 75 Bohnenberger 35 16 40 Messier 13 2 48 the Altai Scarp. Brisbane 47 50 65 Metius 81 40 44 Rheita A deep crater with sharp walls. Very bright craterlets near Goclenius 52 10 45 Reichenbach 48 30 48 the regular, conspicuous Delambre. In many ways they Gutenberg 72 8 41 Rheita 68 37 47 resemble Alfraganus.
Hagecius 81 60 46 Riccius 80 37 26 Theophilus One of the most superb features of the Moon, Halley 35 8 6 Rosse 16 18 35 and in every way the equal of Copernicus except that it is Hecataeus 23 84 Sacrobosco 84 24 17 Helmholtz 97 72 78 Steinheil 70 50 48 not a ray-centre. It is very deep, with peaks rising to Hind 26 8 7 Stevinus 70 33 54 metres 14, feet above the floor.
It adjoins Cyrillus, which is less Albategnius 12 4 Tacitus 40 16 19 regular and in turn adjoins very rough-floored Catharina. A member of the Eastern Chain, but less Humboldt, 27 81 Theophilus 12 26 regular than Langrenus or Petavius, and presumably older.
Wilhelm Torricelli 19 5 29 It has no central peak, and in places the walls are broken. Isidorus 48 8 33 Vendelinus 16 62 Vlacq A deep, well-formed crater with a central peak; it is a Janssen 46 40 Vlacq 90 53 39 member of a rather complex group, of which other mem- Kant 30 11 20 Watt 72 50 51 La Caille 53 24 1 Webb 26 1 60 bers are Hommel and Hagecius. Langrenus 9 61 Werner 66 28 3 Webb A crater very near the lunar equator, with a darkish floor and a central hill; centre of system of short, faint rays.
M f to Orbi. As the Earth catches 7 Sun 1 Mars up and passes it, the movement will seem to be retrograde, so that between Orbi 3 and 5 Mars will appear to t o f E a rt h go backwards in the sky — east to west, against the O r b it o f M a r s stars, instead of west to east. Because their 6 November ; followed by that of 15 November En passant, there can surely be nobody now living who can remember seeing a transit of Venus!
At but Mars has only reached exceptional Pluto — they seem to keep to a well-defined other times the phase may be crescent, half dichotomy , M2. The Earth has to catch band around the sky, termed the Zodiac. There are twelve or gibbous between half and full.
At new, the planet is at Mars up before there is official Zodiacal constellations, though a thirteenth, inferior conjunction; when full, it is at superior conjunc- another opposition, with the Ophiuchus the Serpent-bearer does cross the zone for tion.
These movements mean that the inferior planets are Earth at E2 and Mars at M3. They never remain above the horizon to the Sun than we are, and have their own way of behav- throughout a night.
They seem to stay in the same general area of the sky The superior planets, the orbits of which lie beyond as the Sun, which makes them awkward to observe — par- that of the Earth in the Solar System, can reach superior ticularly in the case of Mercury, where the greatest elonga- conjunction — though for obvious reasons they can never tion from the Sun can never be as much as 30 degrees.
When seen at right They show phases similar to those of the Moon, from new angles to the Sun, they are said to be at quadrature. When to full, but there are marked differences. At new phase, the near quadrature Mars can show an appreciable phase — dark side of the planet is turned towards us, and we cannot down to 85 per cent — so that when viewed through a see it at all unless the alignment is perfect, when the planet telescope its shape resembles that of the Moon a day or will appear in transit as a dark disk crossing the face of the two from full.
The giant planets are so far away that their Sun. This does not happen very often; Venus was last in phases are inappreciable. When the Sun, the Earth and a planet are lined up, Transits of Mercury are less uncommon; the last was on with the Earth in the mid position, the planet is at opposi-.
Saturn almost occulted by the Moon, photographed through a cm inch reflector. Note the smallness of Saturn! The interval between one opposi- Jupiter, because they are always so brilliant; Mercury is tion and the next is known as the synodic period.
It is clear that oppositions do not occur every Neptune and Pluto are much fainter. Oppositions of Mars occur when at its faintest it is little brighter than the Pole Star, in , and , but not in or As the though its strong red colour will usually betray it. The giant planets are so much further away, and be found without difficulty once initially identified.
Mercury M ercury, the innermost planet, is never easy to study from Earth. It is small, with a diameter of only kilometres miles ; it always stays in the same region this was also the length of the axial rotation period, in which case Mercury would always keep the same face turned towards the Sun, just as the Moon does with respect of the sky as the Sun, and it never comes much within to the Earth; there would be an area of permanent day, a 80 million kilometres 50 million miles of us.
However, this has been shown to be wrong. The real rota- The orbital period is 88 days. It was once assumed that tion period is Sidereal period So far, this Oblateness Negligible will see the Sun pass the zenith, stop, and move backwards is the only spacecraft to Albedo 0. There are two hot poles, one or the Diameter km miles it was also the first to use other of which will always receive the full blast of solar the gravity-assist technique.
An observer 90 It has provided us with degrees away will have a different experience; the Sun will our only good maps of rise at perihelion, so that after first coming into view it will the surface, and has shown sink again before starting its climb to the zenith. Even so, Mercury has a globe which is denser than that of any it was able to image less other planet apart from the Earth. There seems to be an than half the surface, so iron-rich core about kilometres miles in diam- that our knowledge of the eter larger than the whole of the Moon , containing about topography of Mercury is Earth 80 per cent of the total mass; by weight Mercury is 70 per still very incomplete.
The core is presumably molten, and above it comes a kilometre mile mantle and crust composed of silicates. Most of our detailed knowledge of Mercury has been obtained from one probe, Mariner It was launched on 3 November , and after by-passing the Moon made rendezvous with Venus on 5 February The gravity field of Venus was used to send Mariner in towards an encounter with Mercury, and altogether there were three active passes before contact was lost: The last messages were received on 24 March , though no doubt Mariner is still orbiting the Sun and still making periodical approaches to Mercury.
As expected, the atmosphere proved to be almost non- existent. The polarity of the field is the same as ours; that is to say, a compass needle would point north. It has to be admitted that Mercury is not a rewarding telescopic object, and little will be seen apart from the characteristic phase. Any form of life there seems to be totally out of the question.
Note that, in general, the arrangement of the craters follows the lunar pattern; small craters break into larger ones, not vice versa. There are also ray centres. The north pole is at the top. This is also Magnetopause an image from Mariner The discovery of a Mercurian magnetic field was something of a surprise.
No radiation belts can form, but there is a definite interaction between the Mercurian field and the solar wind; there is a well-defined bow-shock. The presence of a magnetic field is certainly due to the comparatively large iron-rich core of the planet. Features of Mercury Typical craters with central peaks. M ercury is above all a cratered world. The formations range from small pits up to colossal structures larger than anything comparable on the Moon.
Small craters below 20 kilometres 12 miles in diameter are, in general, bowl-shaped; larger craters have flatter floors, often with terraced walls and central peaks.
As with the Moon, the distribution is non- random. There are lines, chains and groups, and where one formation breaks into another it is virtually always the 90 smaller crater which is the intruder. It few large structures but many craterlets in the 5 to 10 kilo- has a central peak complex, metres 3 to 6 miles range; these are not found on the terraced walls, and displays Moon or Mars.
Neither are the lobate scarps, cliffs from 80 km ejecta deposits. Of the basins, much the most imposing is Caloris, which has some points in common with the lunar Mare 70 Imbrium. It is kilometres over miles in diam- eter and surrounded by mountains rising to between and metres and 10, feet above the floor. It covers 60 , square kilometres , square miles , and consists of hills, depressions and valleys which have destroyed older features.
Evidently the formation of this terrain is linked with the origin of Caloris. It has been estimated that the Caloris Basin is about million years old, 40 and that extensive vulcanism ended about million years ago.
It has been suggested, on the basis of radar observa- diameter Overall. Craters such as this tions, that there may be ice inside some of the polar Multiple central peaks are thought to be relatively craters, whose floors are always shadowed and are there- No central peaks young, for rays emanating fore intensely cold, but the idea of ice on a world such as from them cross all other Mercury does not seem very plausible.
These high It is a pity that our coverage of Mercury is so incom- 0 km albedo, wispy filaments plete; for example, only half the Caloris Basin was in 15 Inner ring diameter consist of fine particles sunlight during the three active passes of Mariner For of ejecta. The black streak more detailed information we must await the results from 10 towards the left indicates a a new spacecraft.
Craters are generally circular, have ejecta rim deposits, fields of secondary craters, terraced inner walls and central peaks, or even concentric inner rings. The smallest craters are bowl-shaped; with increasing size there may be a central peak, then inner terracing of the walls.
Still larger craters have more frequent central peaks, and in the very largest structures complete or partial concentric inner rings may develop.
The change from one type to the next occurs at lower diameters on Mercury than on the Moon. This composite mosaic was compiled from Mariner 10 images which have different resolution limits, so that the degree of detail is not the same everywhere.
The floor of the basin, with its central fractures and its outer region of sinuous ridges, is well shown. There are many small craters on the outer eastern floor; the large crater in the extreme north-east corner of the image is Van Eyck, km miles in diameter.
The Basin is km over miles in diameter, and is bounded by a ring of smooth mountain blocks rising 1 to 2 km 0. Unfortunately only part of it was recorded from Mariner 10; at each encounter the same regions were available. About 80 per cent of 10—20 km 6—12 mile Mercurian craters are terraced; on the Moon only 12 per cent of craters in the same class are.
Schiaparelli observed in broad daylight, when both Mercury and the Sun were high in the sky. He believed the rotation period to be synchronous, so that the same regions were always in sunlight, and he recorded various bright and dark features.
A more detailed map was published in by E. He too believed in a synchronous rotation, and also thought wrongly that the Mercurian atmosphere was dense enough to sup- port clouds. Ahmad Baba Ve n u s enus, the second planet in order of distance from the the crescent phase.
It seemed to be real, but few people V Sun, is as different from Mercury as it could possibly be. Yet telescopically Venus is a It was suggested that Venus might be in the condition disappointment. Little can be seen, and generally the disk of the Earth during the Coal Forest period, with swamps appears blank.
We are looking not at a solid surface, but at and luxuriant vegetation of the fern and horse-tail variety; the top of a layer of cloud which never clears.
Before the as recently as the early s many astronomers were Space Age, we knew very little about Venus as a world. The temperature was high enough to turn Venus into a raging orbital period is Certainly it had been established that the almost circular.
The terminator Orbital eccentricity 0. Apparent diameter max. The atmospheric pressure was found to be around min. The reason Albedo 0. According to one Diameter 12, km miles theory, Venus was hit by a massive body early in its evol- ution and literally knocked over. This does not sound very plausible, but it is not easy to think of anything better.
It has been found that the top of the atmosphere lies around kilometres miles above the surface, and that the upper clouds have a rotation period of only 4 days. The upper clouds lie at an altitude of 70 kilometres 44 miles , and there are several definite cloud-layers, though below 30 kilometres 19 miles the atmosphere is relatively clear and calm. As the phase shrinks, the apparent diameter increases. This picture was taken on 6 February , one day after Mariner 10 flew past Venus en route for Mercury.
The photograph was made by first computer- enhancing several television frames, and then forming a mosaic and retouching them.
The rock was reddish-brown, and the sky brilliant orange. Pioneer Venus 2 visited Venus in The Bis ecause we can never see the surface of Venus, the only way to map it is by radar. The higher regions tend to be rougher than the landers which sent back lowlands, and this means that in radar they are brighter in data during their descent. The map was compiled as There are two main upland areas, Ishtar Terra and a false-colour representation Aphrodite Terra. The other red higher areas.
Ishtar plateau. At its eastern end are the Maxwell Mountains, generated by computer two images show the and Aphrodite stand out the highest peaks on Venus, which rise to 11 kilometres using Magellan data. They typically Venusian highland very clearly. It has been nearly 7 miles above the mean radius and 8. Aphrodite straddles The image immediately bordered by plains. Diana Chasma, the deepest point sulphuric acid and releasing on Venus, adjoins Aphrodite.
En passant, it has been decreed that all names of fea- tures in Venus must be female. The only exception is that of the Maxwell Mountains.