Suppose that you live in Charleston, South Carolina. Imagine that you go to bed, and in the morning, you awaken in Sydney, Australia, and do not know that you have been transported to a location south of the equator. It is a clear morning. The Sun appears to rise normally enough, but after awhile you notice something strange. Rather than progressing generally south and west, as the Sun always does during the early morning hours in the northern hemisphere, the Sun moves north and west. At high noon it sits squarely in the northern sky. The weather is improbable, everyone has a strange accent, and the phone numbers are weird. You look at the cover of the phone book or tune into a local radio station, and the mystery is solved—except, of course, for how you got transported halfway around the world without remembering any of the trip.
If you normally live in Sydney and some morning you awaken in Charleston, a similar surprise awaits you. In fact, if you come from “down under” and are transported to America by surprise, you’ll be every bit as jarred as an American who is transported to Australia.
Southern celestial coordinates are similar to northern celestial coordinates. They operate according to the same mathematics. The main difference is that the two coordinate hemispheres are mirror images of one another. While the northern heavens seem to rotate counterclockwise around the north celestial pole, the southern Sun, Moon, planets, and stars seem to rotate clockwise around the south celestial pole.
Recall your middle-school algebra class. Imagine the cartesian coordinate plane. The northern hemisphere is akin to the first and second quadrants, where the y values are positive; the southern hemisphere is cousin to the third and fourth quadrants, where the y values are negative. No particular quadrant is preferable to or more special than any of the other three. So it is with Earth and sky. Fully half the points on the surface of Earth are south of the equator. It is no more unusual in this world for the Sun to shine from the north at high noon than it is for the Sun to shine from the south. Only the extreme polar regions experience conditions that most people would call truly strange, where the Moon or Sun can stay above the horizon for days or weeks at a time, circling the points of the compass.
In the southern hemisphere, azimuth bearings are measured clockwise with respect to geographic north, just as they are in the northern hemisphere. However, an alternative system can be used; azimuth can be defined as the angle clockwise relative to geographic south. In this latter system, the range of possible values is from 0 degrees (south) through 90 degrees (west), 180 degrees (north), 270 degrees (east), and up to, but not including, 360 degrees (south again). This is shown in Fig. 3-1. The bearing of 360 degrees is omitted to avoid ambiguity, just as is the case with the north-based system. You will never hear of an azimuth angle less than 0 degrees nor more than 360 degrees, at least not in proper usage.
The elevation of an object in the sky is the angle, in degrees, subtended by an imaginary arc running away from the object until it intersects the horizon at a right angle. For visible objects over flat terrain, this angle can be as small as 0 degrees when the object is on the horizon or as large as 90 degrees when the object is directly overhead. This is exactly the same scheme as is used in the northern hemisphere. Elevation bearings are measured upward from the horizon to 90 degrees and downward below the horizon to –90 degrees. If the horizon cannot be seen, then it is defined as that apparent circle halfway between the zenith and the nadir.
There are two points in time every year when the Sun’s elevation, measured with respect to the center of its disk, is positive for exactly 12 hours and negative for exactly 12 hours. One of these time points occurs on March 21, give or take about a day; the other occurs on September 22, give or take about a day. At the equinoxes, the Sun is exactly at the celestial equator; it rises exactly in the east and sets exactly in the west, assuming that the observer is not at either of the geographic poles. The names vernal and autumnal, as used in the northern hemisphere, are not really correct in the southern hemisphere because the seasons are reversed compared with those in the north. Thus it is best to speak of the March equinox and the September equinox.
Figure 3-1. Azimuth based on a southerly point of reference.
The crude celestial maps of Fig. 3-2 show the situation at either equinox. That is, the date is on or around March 21 or September 22. You can deduce this because the Sun rises exactly in the east and sets exactly in the west, so it must be at the celestial equator. At the latitude of Sydney, the Sun is 35 degrees away from the zenith (55 degrees above the northern horizon) at high noon on either of these days. The south celestial pole, which unfortunately has no well-defined sentinel star, as is the case for the northern hemisphere, is 35 degrees above the southern horizon all the time. The heavens seem to rotate clockwise around the south celestial pole. In the drawing at A, imagine yourself lying flat on your back, with your head facing north and your feet facing south. In the drawing at B, imagine yourself rotated 180 degrees, that is, with your head facing south and your feet facing north. Either orientation is valid astronomically, and you will find star maps that use either scheme.
Figure 3-2. Az/el sky maps for midafternoon at 35 degrees south latitude on or around the March or September equinoxes. At A, top of head facing north; at B, top of head facing south.
Every day the Sun moves slightly toward the east with respect to the background of stars. At the March equinox, the Sun is at the celestial equator and is located in a certain position with respect to the stars. This represents the reference point for right ascension (RA) and declination (dec). As time passes, the Sun rises about 4 minutes later each day relative to the background of stars. The sidereal (star-based) day is about 23 hours and 56 minutes long; the synodic (sun-based) day is precisely 24 hours long. In the southern hemisphere, the Sun’s motion relative to the stars is from left to right.
In the drawings of Fig. 3-2, the Sun is at dec = 0 degrees. Suppose that these drawings represent the situation at the March equinox. This point among the stars is the zero point for right ascension (RA = 0 h). As autumn passes and the Sun follows a lower and lower course across the sky, the declination and right ascension both increase for a while. Remember that right ascension is measured in hours, not in degrees. There are 24 hours of right ascension in a circle, so 1 hour (written 1 h or 1h) of RA is equal to 15 degrees.
Let us begin following the Sun during the course of the year starting at the March equinox. As the days pass during the months of April, May, and June, the Sun stays above the horizon for less and less of each day, and it follows a progressively lower course across the sky. The change is rapid in the first days after the equinox, and becomes more gradual with the approach of the June solstice, which takes place on around June 22 give or take a day. This might be called the “winter solstice,” but again, to avoid confusion with northern-hemisphere-based observers who call it the “summer solstice,” it is better to name the month in which it occurs.
At the June solstice, the Sun has reached its northernmost declination point, approximately dec = +23.5 degrees. The Sun has made one-quarter of a complete circuit around its annual “lap” among the stars and sits at RA = 6 h. This situation is shown in Fig. 3-3 using the same two az/el coordinate schemes as those in Fig. 3-2. The gray line represents the Sun’s course across the sky. As in Fig. 3-2, the time of day is midafternoon. The observer’s geographic latitude is the same too: 35°S.
Figure 3-3. Az/el sky maps for midafternoon at 35 degrees south latitude on or around June 21.
After the June solstice, the Sun’s declination begins to decrease, slowly at first and then faster and faster. By late September, the other equinox is reached, and the Sun is once again at the celestial equator, just as it was at the March equinox. But now, instead of moving from south to north, the Sun is moving from north to south in celestial latitude. At the September equinox, the Sun’s RA is 12 h. This corresponds to 180 degrees.
Now it is the spring season in the southern hemisphere, and the days are growing long. The Sun stays above the horizon for more and more of each day, and it follows a progressively higher course across the sky. The change is rapid during September and October and becomes slower and slower with the approach of the December solstice, which takes place on December 21, give or take a day.
At the December solstice, the Sun’s declination is at its southernmost point, approximately dec = –23.5 degrees. The Sun has gone through three-quarters of its annual “lap” among the stars, and sits at RA=18 h. This is shown in Fig. 3-4 using the same two az/el coordinate schemes as those in Figs. 3-2 and 3-3. The gray line represents the Sun’s course across the sky. As in Figs. 3-2 and 3-3, the time of day is midafternoon. The observer hasn’t moved either, at least in terms of geographic latitude; this point is still at 35°S.
After the December solstice, the Sun’s declination begins to increase gradually and then, as the weeks pass, faster and faster. By late March, the Sun reaches an equinox again and crosses the celestial equator on its way to forsaking the southern hemisphere for another autumn and winter. The “lap” is complete.
The Greeks didn’t name the southern circumpolar constellations, but many of the star groups near the equator, as seen from “down under,” are the same ones that the Greeks made famous. The only difference is that they are all upside down.
In this chapter, the general shapes of the better-known southern constellations are shown. To see where these constellations are in the sky from your location this evening, go to the Weather Underground Web site at the following URL:
Figure 3-4. Az/el sky maps for midafternoon at 35 degrees south latitude on or around December 21.
Type in the name of your town and country, and then, when the weather data page for your town comes up, click on the “Astronomy” link. There you will find a detailed map of the entire sky as it appears from your location at the time of viewing, assuming that your computer clock is set correctly and data are input for the correct time zone.
From the latitude of 35°S, the circumpolar constellations encompass much of the sky. At some time or other during the year, it is possible to see more of the sky at lower latitudes (closer to the equator) than at higher latitudes (closer to the poles). If you live in Sydney, Buenos Aires, or Cape Town, you have a slight advantage in this respect over your counterparts who live in Minnesota and a bigger advantage over people in Scotland. However, the portion of the sky that stays above the horizon, no matter what time of the year you stargaze in the evening sky, becomes smaller as you go closer to the equator. Observers in chillier climes get to see more circumpolar constellations but less of the complete celestial sphere; people in warmer places get to see more of the celestial sphere, but they have to choose the proper times to see specific constellations near the pole.
In this chapter, as in Chapter 2, stars are illustrated at three relative levels of brightness. Dim stars are small black dots. Stars of medium brilliance are larger black dots. Bright stars are circles with black dots at their centers. But the terms dim, medium, and bright are not intended to be exact or absolute. In downtown Sydney, some of the dim stars shown in these drawings are invisible, even under good viewing conditions, because of scattered artificial light. After your eyes have had an hour to adjust to the darkness on a moonless, clear night in the outback, some of the dim stars in these illustrations will be easy to see. The gray lines connecting the stars are included in the diagrams only to emphasize the general shapes of the constellations.
We need a time of reference for our circumpolar observations, and mid-April is as good a time as any. Imagine that you are in the countryside near Sydney or Cape Town or Buenos Aires and that you go outdoors to stargaze at around 10:00 P.M. Assume that the sky is clear, there is no haze, and the Moon is below the horizon so that its light does not interfere with stargazing. You know that the south celestial pole is 35 degrees above the southern horizon. You search for a significant star, or at least a constellation, to mark the spot using the “fist rule.” (Hold your right arm out straight and make a tight fist. Point the knuckles toward your right. The top of your fist is about 10 angular degrees from the bottom.) You find the southern horizon using a compass or your knowledge of the area and proceed three and a half fists up into the sky. There is nothing significant. The south polar region is devoid of bright or even moderately bright stars. This caused some trouble for mariners who ventured south of the equator. They needed a convenient way to locate the south celestial pole.
As you stand facing toward the south, you will see, high in the sky, a group of four stars forming a kitelike shape. This is Crux, more commonly called the southern cross. Just below it, somewhat dimmer, is a star group shaped somewhat like a ladle. This is Musca or Musca Australis, the southern fly. Look at these two constellations carefully, and make educated guesses as to their centers (Fig. 3-5). The center of Crux is easy to decide on, but the center of Musca is a little tougher. Pick a point on the handle of the ladle, just above the scoop. These two constellation-center points are separated by about 10 degrees of arc, a fact that you can verify by the fist rule. Now go two fists down toward the southern horizon from the center point of Musca. This will give you a point close to the south celestial pole.
Just below and to the left of Crux, there is a group of three stars that form a triangle. It’s almost a perfect equilateral triangle, with the apex at the bottom and the base on top (Fig. 3-6). This is Triangulum Australis, the southern triangle, often called simply Triangulum. Below this constellation and to its right is Apus, the bird of paradise. It is a small, dim constellation and at this time of the year looks something like a lawn mower (if you have a good imagination).
Figure 3-5. Crux, the southern cross, and Musca, the southern fly, as observed in mid-April from the latitude of Sydney, Australia.
Figure 3-6. Triangulum, the southern triangle; and Apus, the bird of paradise.
Below Triangulum, in the south-southeast sky, is a large group of dim stars. This is the constellation Pavo, the peacock (Fig. 3-7). This is an inappropriate name for such an inconspicuous group of stars. However, you might, with some effort, imagine a large, fan-shaped set of tail feathers, with the bird, at this time of year, appearing upright.
Figure 3-7. Pavo, the peacock.
Low in the southern sky, almost grazing the horizon, is Tucana, the toucan (Fig. 3-8). At this time of year, you can imagine this dim group of stars as having the shape of a bird lying on its side with its beak pointed down and to the right. This constellation contains the Small Magellanic Cloud, a satellite of our Milky Way galaxy.
In the south-southwest, below and to the right of the south celestial pole, there are three constellations of note: Hydrus, the little snake, Reticulum, the net, and Mensa, the table. These are shown in Fig. 3-9. It is hard to imagine how any of these star groups got the names they got. Mensa contains part of the Large Magellanic Cloud, another satellite of our galaxy similar to the Small Magellanic Cloud. Both of the Magellanic Clouds are named after the explorer Magellan, whose ship made the famous round-the-world trip hundreds of years ago and who sailed through the far southern oceans.
Figure 3-8. Toucana, the toucan.
Figure 3-9. Hydrus, the little snake; Reticulum, the net; and Mensa, the table.
Above and to the right of the celestial pole are Volans, the flying fish, and Carina, the keel or ship (Fig. 3-10). Carina is noteworthy because it contains the yellowish white star Canopus, which is the second brightest nighttime star after Sirius.
Figure 3-10. Volans, the flying fish, and Carina, the keel. Carina contains the well-known bright star Canopus.
The two constellations closest to the south celestial pole are Chameleon, the lizard, and Octans, the octant. The stars in these groups are so dim that unless you are out in the country away from city lights, you will not see them. Also, if the Moon is near full phase and is above the horizon, its scattered light might wash these constellations out. At this time of the year, Octans in the evening sky appears as a tall, slender triangle immediately to the east of the celestial pole, and Chameleon is near and above it (Fig. 3-11). Apus, the bird of paradise, appears in this group too, centered about 12 degrees (a little more than one fist) above and to the left of the pole.
Figure 3-11. Octans, the octant; Chameleon, the lizard; and Apus, the bird of paradise, are the three constellations closest to the south celestial pole.
Imagine that it is still the same night and still the same time (10:00 P.M.), and you turn your attention toward the east, north, and west, that part of the sky not confined to the vicinity of the celestial pole. Constellations in this part of the sky rise and set; they are not always above the horizon. As is the case in the northern hemisphere, the farther from the pole a constellation is located, the more time it spends each day below the horizon. A star at the equator spends exactly half the sidereal day, or about 11 hours and 58 minutes, above the horizon and half the time out of sight “beneath Earth.” Ultimately, for observers at 35 degrees south latitude, constellations with declinations of more than +55 degrees (within 35 degrees of the north celestial pole) never make it above the northern horizon.
Libra is a group of faint stars representing the scales of justice. It is high in the northeastern sky. It has the general shape of a trapezoid or diamond at this time of the year (Fig. 3-12).
Figure 3-12. Libra, the scales of justice, looks like a diamond.
Virgo, the virgin, is fairly high in the north-northeast sky. As viewed from this angle, it is shaped rather like a scorpion (Fig. 3-13). Virgo contains the bright star Spica.
Figure 3-13. Virgo, the virgin, looks something like a scorpion.
Leo, the lion, is high in the northwest sky. It bears no resemblance to a resting lion or Sphinx, as it does when looked at from north of the equator. Instead, its shape more nearly resembles that of a mangled coat hanger (Fig. 3-14) or a laundry iron held upside down. The bright star Regulus dominates.
Cancer, the crab, is low in the northwest sky (Fig. 3-15). Next to Cancer is Canis Minor, the little dog, which contains the prominent star Procyon. In ancient Greek mythology, souls were said to enter the world by passing down from the heavens through Cancer.
Figure 3-14. Leo, the lion, lacks his regal nature south of the equator.
Figure 3-15. Cancer, the crab, and Canis Minor, the little dog.
Low in the northeastern sky, near the horizon, is a group of several stars that form an inverted-U or Greek letter omega shape. These stars form the constellation Corona Borealis, the northern crown (Fig. 3-16). This constellation is dominated by the moderately bright star Alphecca, also known as Gemma.
Figure 3-16. Corona Borealis, the northern crown.
Just to the left of the northern crown you will see a brilliant, twinkling star at an elevation of about 20 degrees in the northeast or north-northeast sky. This is Arcturus. If you use your imagination, you might see that this star forms the point where a fish joins its tail (Fig. 3-17). The fish seems to be swimming straight downward. This is Bootes, the herdsman. Just to the left of Bootes, near the northern horizon, is a group of three rather dim stars. These are Bootes’ canine companions, Canes Venatici.
A large portion of the autumn evening sky is occupied by three constellations consisting of relatively dim stars. These are Corvus, the crow, Crater, the cup, and Hydra, the sea serpent or water snake (Fig. 3-18). Hydra stretches from low in the northwest, nearly through the zenith, to high in the eastern sky. Corvus and Crater are both high in the north, just below Hydra.
Figure 3-17. Bootes, the herdsman, and Canes Venatici, his dogs.
Figure 3-18. Corvus, the crow; Crater, the cup; and Hydra, the sea serpent.
Now imagine that it is the middle of July—the dead of the southern-hemispheric winter—and that you are outdoors at around 10:00 P.M. The circumpolar constellations are all still above the horizon, but they have rotated 90 degrees clockwise around the pole from their positions in April. The noncircumpolar constellations have moved from east to west. As you look generally away from the circumpolar sky, you should be able to make out the following groups of stars, which are also visible from the northern temperate latitudes at this time of year.
Near the northern horizon, or just a little west of due north, is a moderately dim group of stars forming a trapezoid with limbs (Fig. 3-19). This is Hercules, the warrior. His nemesis, Draco, is mostly out of sight below the horizon. The well-known globular cluster M13 is in this constellation, although from the southern temperate latitudes the viewing is somewhat less favorable than it is from northern locations.
Figure 3-19. Hercules, the warrior, is low in the northern sky on southern-hemispheric winter evenings.
High in the eastern sky is Capricornus (also called Capricorn), the goat (Fig. 3-20). This goat has the tail of a fish, according to the myths, and dwells at sea. Ancient Greek mythology held that on its way to heaven after death of the body, the human soul would pass through this constellation.
Figure 3-20. Capricornus, also known as Capricorn, the sea goat.
Near the zenith, you will see Sagittarius, the centaur (Fig. 3-21). Sagittarius lies in the direction of the densest part of our galaxy. If it were not for interstellar dust, which is concentrated along the plane of the Milky Way, this constellation and those near it would be obscured by the brilliance of the galactic core.
Figure 3-21. Sagittarius, the centaur, is near the zenith on southern-hemispheric winter evenings.
Just to the west of Sagittarius, also near the zenith, is Scorpius (also called Scorpio), the scorpion (Fig. 3-22). This constellation is one of the few that bears some resemblance to the animal or object it represents. The eye of the scorpion is the red giant star Antares, which varies in brightness.
Figure 3-22. Scorpius, the scorpion, contains the red star Antares, and is just to the west of Sagittarius.
High in the northwestern sky are the constellations Ophiuchus, the snake bearer, and Serpens, the snake (Fig. 3-23). As with most of the other constellations near the celestial equator, these two are inverted with respect to their appearance as seen from the northern hemisphere.
Low in the northern sky you will see the bright star Vega, flanked by a small parallelogram of dimmer stars. The quadrilateral forms the constellation Lyra, the lyre. To the right of Vega, grazing the horizon, is another bright star, Deneb, that is at the tip of the tail of Cygnus, the swan. Above and slightly to the right of Deneb is a third bright star, Altair. This is part of the constellation Aquila (Fig. 3-24). In the northern hemisphere, these three stars stand high in the sky and are sometimes called the summer triangle. However, in the southern hemisphere they have no special distinction apart from their relative brilliance.
Figure 3-23. Ophiuchus, the serpent bearer, holds Serpens, the snake.
Now imagine that it is around 10:00 P.M. in the middle of October and that you are at the latitude of Sydney, Buenos Aires, or Cape Town (approximately 35°S). New constellations have risen in the east, and old ones have set in the west. Here are constellations we have not described before that now occupy prominent positions in the sky.
Figure 3-24. Lyra, the lyre; Cygnus, the swan; and Aquila, the eagle. These constellations are marked by the bright stars Vega, Deneb, and Altair.
In the north you will see Pisces, the two fish. In the north-northeastern sky is Aries, the winged ram (Fig. 3-25). The fish of Pisces are, according to mythology, joined at their tails, and Aries has fleece of gold.
High in the northeastern sky is Cetus, the whale or sea monster (Fig. 3-26). The variable star Mira is sometimes visible in this constellation. The star Tau Ceti is thought to be a candidate for having a solar system similar to ours and possibly an earthlike planet.
Figure 3-25. Pisces, the fishes, and Aries, the ram.
Figure 3-26. Cetus, the whale, contains the variable star Mira.
Low in the north-northwestern sky is Pegasus, the winged horse. Near the northern horizon, Andromeda, representing a princess, rides the horse alongside the Milky Way (Fig. 3-27). Andromeda contains a spiral galaxy similar to our own galaxy, but it is 2,200,000 light-years away, about 20 times the diameter of the Milky Way’s spiral disk. The Great Nebula in Andromeda, as it was originally called, is too near the horizon, as viewed from the southern temperate latitudes, to present itself well to casual observers.
Figure 3-27. Pegasus, the winged horse, and Andromeda, the Ethiopian princess who married Perseus.
High in the northwest sky, you will see Aquarius, the water bearer (Fig. 3-28). Aquarius supposedly brings love and peace. In ancient mythology, this constellation was seen as a person pouring water from a jug.
Figure 3-28. Aquarius, the water-bearer, traverses the northwestern sky on spring evenings in the southern hemisphere.
High in the western sky, nearly at the zenith, is Piscis Austrinus, also called Piscis Australis. This is the southern fish and contains the bright star Formalhaut (Fig. 3-29). Immediately to the south of it is Grus, the crane.
Figure 3-29. Piscis Austrinus, the southern fish, and Grus, the crane, are near the zenith on southern-hemisphere spring evenings.
Finally, let’s look at the late-evening sky in the middle of January. Here are the prominent new constellations of the southern-hemispheric summer as they appear from the latitude of Sydney, Buenos Aires, or Cape Town around 10:00 P.M. local time.
Just north of the zenith are Canis Major, the big dog, and Lepus, the rabbit (Fig. 3-30). Canis Major is easy to spot because of the brilliant white star, Sirius, nearly overhead at this latitude in the evening at this time of the year. Sirius is also called the Dog Star and is the brightest star in the sky except for the Sun.
Figure 3-30. Canis Major, the big dog, and Lepus, the rabbit.
Somewhat below and to the left of Sirius, but still high in the sky, is Orion, the hunter (Fig. 3-31). If you look at Orion’s central region with good binoculars or a wide-angle telescope, you will see the Great Nebula in Orion, a vast, glowing cloud of gas and dust in which new stars are being born. Orion contains two bright stars, Betelgeuse (also spelled Betelgeux), a red giant, and Rigel, a blue-white star.
Low in the north-northwest sky is Taurus, the bull (Fig. 3-32). This constellation contains the bright star Aldebaran. Below Taurus is a group of several stars known as the Pleiades. At this latitude, the Pleiades are less spectacular than they are as seen from the northern hemisphere, but on an especially dark night, with a good wide-angle telescope, their splendor shines through. From extreme southern latitudes, the Pleiades never rise above the northern horizon.
Figure 3-31. Orion, the hunter, contains a nebula and two well-known bright stars.
Figure 3-32. Taurus, the bull, and the Pleiades, also known as the Seven Sisters (although there are really far more than seven of them).
Beginning at the feet of Orion and winding its way high across the western sky into the circumpolar region is a string of relatively dim stars. This constellation is Eridanus, the river. It, like Cetus, the whale, contains a star, Epsilon Eridani, that is thought by many scientists to have a solar system like ours.
Gemini is low in the north-northeast sky. This constellation has the general shape of a long, thin, backward letter C if you stand facing north and look up at it (Fig. 3-33). At the right-hand extreme are two relatively bright stars, Castor and Pollux, named after the twin sons of the mythological Greek god Zeus.
Grazing the northern horizon is the constellation Auriga. It contains the bright star Capella (Fig. 3-34). From extreme southern latitudes, Capella never makes it above the northern horizon, although from the more northerly temperate regions and from the southern tropics it is a brilliant, twinkling landmark in the sky.
Figure 3-33. Gemini contains the stars Castor and Pollux, and appears low in the north-northeast sky in the southern-hemispheric summer.
Figure 3-34. Auriga, the charioteer, contains the bright star Capella.
QuizRefer to the text if necessary. A good score is 8 correct. Answers are in the back of the book.
1. In the southern hemisphere, elevation is measured in the same way as it is in the northern hemisphere, with the following exception:
(a) It is a negative angle rather than a positive angle.
(b) It is expressed in radians rather than in degrees.
(c) It is measured with respect to the south pole rather than the north pole.
(d) There are no exceptions.
2. Which of the following stars is also known as “south Polaris”?
(a) Formalhaut
(b) Capella
(d) None of the above
3. The spring equinox in the southern hemisphere occurs in which month?
(a) March
(b) June
(c) September
(d) December
4. Suppose that it is a few days after the summer solstice according to people who live in Sydney, Australia. The Sun’s declination is
(a) slowly decreasing.
(b) rapidly decreasing.
(c) slowly increasing.
(d) rapidly increasing.
5. At a latitude of 35°S, the angular radius of the south circumpolar region is
(a) 70 degrees of arc.
(b) 55 degrees of arc.
(c) 35 degrees of arc.
(d) impossible to determine, not enough data are given.
6. Orion is a landmark constellation primarily in which season south of the equator?
(a) Winter
(b) Summer
(c) Spring
(d) Fall
7. At a latitude of 55°S, the northern pole star Polaris would be approximately
(a) 35 degrees above the horizon.
(b) 35 degrees below the horizon.
(c) 55 degrees above the horizon.
(d) 55 degrees below the horizon.
8. A circumpolar constellation as viewed from Cape Town, South Africa, is
(a) Ursa Minor.
(b) Octans.
(c) Ursa Major.
(d) Draco.
9. A star that lies on the celestial equator as seen from 45°N would lie approximately where as seen from 45°S?
(a) On the celestial equator
(b) Near the north celestial pole
(c) Near the south celestial pole
(d) The answer cannot be determined from the information given.
10. As the night progresses for an observer in Buenos Aires, Argentina, the south circumpolar stars seem to
(a) revolve counterclockwise around the south celestial pole.
(b) revolve clockwise around the south celestial pole.
(c) rise in the east and set in the west.
(d) never rise above the horizon.
