Star Gazer’s Guide

Star Gazer’s Guide

Stars and Constellations

The Explosion that created the Universe gave birth to trillions of stars, but only 5,000 are visible to the naked eye.

Since only half the sky can be seen at any one time, that means only 2,500 stars will be in your field of vision on the next clear night. Constellations are groups of stars whose patterns remind stargazers of familiar shapes.

Le Soleil couchant. Photo by Elena

Today, astronomers recognize 88 such patterns. Their names and meanings :

Andromeda – Chained Maiden

Antila – Air Pump

Apus – Bird of Paradise

Aquarius – Water Bearer

Aquila – Eagle

Ara – Altar

Aries – Ram

Auriga - Charioteer

Bootes – Herdsman

Caelum – Chisel

Camelopardalis – Giraffe

Cancer – Crab Canes

Venatici – Hunting Dogs

Canis Major – Great Dog

Canis Minor – Little Dog

Capricornius – Sea-goat

Carina – Keel

Cassiopeia – Queen

Centaurus – Centaur

Cepheus – King

Cetus – Whale

Chamaeleon – Chameleon

Circinus – Compasses (art)

Columba – Dove

Coma Berences – Bernice’s Hair

Corona Australis – Southern Crown

Corona Borealis – Northern Crown

Corvus – Crow

Crater – Cup

Crux – Cross (Southern)

Cygnus – Swan

Delphinus – Dolphin

Dorado – Goldfish

Draco – Dragon

Equuieus – Little Horse

Eridanus – River

Fomax – Furnace

Gemini – Twins

Grus – Crane (bird)

Hercules – Hercules

Horologium – Clock

Hydra – Water Snake (female)

Hydrus – Water Snake (male)

Indus – Indian

Lacerta – Lizard

Leo – Lion

Leo Minor – Little Lion

Lepus – Hare

Libra – Balance

Lupus – Wolf

Lynx – Lynx

Lyra – Lyre

Mensa – Table Mountain

Microscopium – Microscope

Monoceros – Unicorn

Musca – Fly

Norma – Square (rule)

Octans – Octant

Ophiuchus – Serpent Bearer

Orion – Hunter

Pavo – Peacock

Pegasus – Flying Horse

Perseus – Hero

Phoenix – Phoenix

Pictor – Painter

Pisces – Fishes

Piscis Austrinius – Southern Fish

Puppis – Stern (deck)

Pyxis – Compass (sea)

Reticulum – Reticle

Sagitta – Arrow

Saggitarius – Archer

Scorpius – Scorpion

Sculptor – Sculptor

Scutum – Shield

Serpens – Serpent

Sextans – Sextants

Taurus – Bull

Telescopium – Telescope

Triangulum – Triangle

Triangulum Australe – Southern Triangle

Tucana – Toucan

Ursa Major – Great Bear

Ursa Minor – Little Bear

Vela – Sail

Virgo – Maiden

Volans – Flying Fish

Vulpecula – Fox.

Planets of the Solar System

Planets of the Solar System

There are eight planets in the solar system, including Earth, but only four besides our own are visible to the naked eye: Venus, Mars, Jupiter, and Saturn. Mercury: The smallest of the planets is Mercury. Its diameter is less than half the earth’s.

Named for the god of the winged messenger, it is the planet closes to the sun and has no satellites. It has been believed for longtime that Mercury always turned the same side toward the sun and that the sunlit part of Mercury had a temperature hotter than 600 degrees Fahrenheit. By contrast, the temperature on the side away from the sun is thought to be -460 degrees Fahrenheit. Venus: Named for the goddess of love and beauty, Venus is almost the same size as Earth and is often called Earth’s “sister planet”.

The brightest of all planets, Venus is shadowed only by the Sun and the moon. It is the first “star” to appear in the evening sky and the last to disappear in the morning. At its brightest, Venus may even be visible during the day. Many astronomers believe that the core of Venus is largely metallic, mostly made of iron and nickel. Because of the dense carbon dioxide clouds enveloping the planet, the surface of Venus can’t be seen. Earth: Ours is the third closest planet to the sun – they are only 93 million miles apart.

Seen from space, the planet appears as a blue ocean sphere with brown and green areas marking the location of its continents. Its diameter at the equator is 7,900 miles, and its atmosphere contains 78 percent nitrogen and 21 percent oxygen, in addition to traces of water in gaseous form, carbon dioxide and other gases. By measuring the radioactive decay of elements in the Earths’ crust, scientists estimate that the planet is about 4.5 billion years old. Mars: Like Earth, Mars has four seasons, but the diameter of Mars is just a little more than half that of Earth’s, and its mass is only about a tenth of ours. Named for the god of war, Mars takes 687 days to complete one revolution of the sun.

About 80 percent of the planet is carbon dioxide. The white caps that cover its poles increase in size during the Martian winter and shrink during the summer. Martian seasons are about twice as long as Earth’s. Jupiter: Next to the sun, Jupiter is the largest and most massive object in the solar system. Named for the leader of the gods, Jupiter has a mass more than twice that of all other planets combined. A body on the surface of Jupiter would weigh 2,64 times what it would weigh on Earth. Jupiter completes a revolution every 10 hours, giving it the shortest day in the solar system. It also has 12 satellites, the largest number of any planet in the solar system.

It is perhaps most famous for its Great Red Spot, which scientists believe is a storm that has been going on for more than 300 years. Saturn: The second largest planet in the solar system, Saturn is named for Titan, the father of Jupiter and the god of sowing. It is best known for its system of concentric rings, which are not visible to the naked eye. The rings are probably composed of debris from a shattered satellite. Saturn is the least dense of all the planets but one of the brightest. Uranus: Visible by the naked eye on a dark, clear night, Uranus is unique because its axis of rotation lies almost in the plane of its orbit. The planet was discovered by the German-English astronomer William Herschel in 1781. Herschel proposed to name the planet Georgium Sidus, in honor of England’s King George III. But in keeping with the tradition of naming planets after Greek gods, it was eventually named after the father of Titan and the grandfather of Jupiter

. Uranus has five known satellites and a mass over 14 times that of Earth’s. Its temperature is thought to be below -300 degrees Fahrenheit. Neptune: Named for the god of the sea, Neptune requires 165 years to complete one revolution of the sun. Its atmosphere is made of methane, hydrogen, ammonia, and helium, and its mass is about 17 times that of Earth. The planet was discovered as a result of a mathematical prediction. Two mathematicians, John Couch Adams and Urbain Le Verrier, calculated that there must be an unknown planet more distant from the sun than Uranus because they could detect the gravitational pull on Uranus.

Pluto : (this planet used to be the 9th planet, but it is now seen as a big asteroid). There is probably little or no atmosphere on Pluto because of its extreme temperature, which is nearly -400 degrees Fahrenheit. From Pluto the sun would only appear as a bright star. While it was named for the odd of the underworld, the planet’s first two letters are also the initials of Percival Lowell, whose research on gravitational forces led him to predict the planet’s existence around the beginning of 20th century. It wasn’t until after Lowell’s death, however that the planet was discovered.

Moonlight Sonata

Moonlight Sonata

Mountains on the Moon

The man in the moon is actually a series of frozen lava fields. The moon is Earth’s only natural satellite and was probably created in the same cosmic event that created the Earth.

It is only 238,860 miles away, making it an object of endless human fascination – and superstition – for millennia. Although its only light is reflected from the sun, it is the brightest object in our night-time sky. In size it is slightly more than a quarter the diameter of the Earth.

Temperatures can be as high as 273 degrees Fahrenheit on the bright side and as low as -274 degrees Fahrenheit on the dark side. There is no air, and thus no liquid water, on the lunar surface. That means the moon has no clouds, winds, rain or snow. Without air and water to cause erosion, the moon’s features are nearly permanent – they include towering mountain ranges and seas of hardened lava.

The astronomer Galileo was the first to study many of these features with the telescope he built in the early 1600s.

The moon’s laval fields are called maria, after the Latin word mare for sea, because in Galileo’s time it was thought that these plains might in fact be oceans, and that there might be life on the moon. The maria look dark from Earth, suggesting to those with a vivid imagination that there is a “a man in the moon”.

The lunar surface has also been pitted with craters from crashing meteorites – over 30,000 can be seen from Earth. The circular depressions range in size from less than a mile to over 100 miles across.

As intriguing as all of these features are, however, none of them can compare with the fact that the pull of the moon’s gravity on the earth’s oceans plays a huge role in creating our daily tides.

The Phases of the Moon

The moon takes slightly longer than 27 days to complete its elliptical orbit around the earth, but because the earth also moves around the sun, it takes 29 days, 12 hours, 44 minutes and 3 seconds to go from one new moon to the next. At the start of each orbit, the moon is directly between the earth and the sun, making the moon invisible because its dark side is toward us.

Gradually, a crescent appears and the moon passes through a waxing phase, in which it grows progressively more visible until it becomes full, and then a waning phase, in which its shape gradually shrinks to invisible again before repeating the cycle.

The Moon has no light of its own : it merely reflects the light of the sun. If the moon did not rotate as it revolves around the earth, we would see all its sides; as it is, we always see the same side. Illustration: Moving beyond the Big Dipper.

If you are curious about what beside the North Star and the Big and Little Dippers are visible in the firmament tonight, don’t rush off to the book-store just yet; sorting through the hundreds of star-gazing guides that fill the racks could leave you more confused than you were to to begin.

Beachgoer's Guide to Tides

A Beachgoer’s Guide to Tides

Skim this to know more about tidal effects than most fishermen Some ancient myth-makers held that the earth’s pulse or breathing caused the tides. The Greeks began to notice the moon’s influence when they began venturing out of the relatively tideless Mediterranean. Our modern understanding of tides is based on Sir Isaac Newton’s equilibrium theory of tides, which described the gravitational attractions of the sun and moon on the earth’s waters.

Today, tides can be predicted with astronomical precision and need no longer be a mystery. Here’s what landlubbers will fin when they are at the beach.

If you live on the East Coast, expect the tides to be semidiurnal: That’s when high and low tides occur twice per lunar day, and the heights of both the first and second set of tides are roughly the same.

A lunar day is 50 minutes longer than a day on Planet Earth, which is why in many places high and low tides occur about 50 minutes later than the corresponding tides of the previous day.

If you live on the West Coast, expect mixed tides: The tides on America’s left coast rise and fall twice per lunar day, but the heights or the second set of tides differ from the first. The different tides each day are termed higher high water, lower high water, higher low water, and lower low water. Their order of occurrence varies over the course of the moon and from place to place.

Along the Gulf of Mexico, the tides are diurnal: Here, high and low tides appear only once every day. About twice a month, near the time of the new and full moon, the tidal range between high and low tides is usually 20 percent above average. These tides, known as spring tides, occur when the sun and moon are in a straight line with the earth. When the sun and moon are at right angles to each other with respect to the earth, tidal ranges between high and low tides are about 20 percent less than average. These tides, known as neap tides, occur around the time of the first and third quarters of the moon.

For another big swing in height between high and low tide, wait until the moon is at perigee: That’s when the moon is at its closest point to the earth each month and is when the tidal range between high and low tide is greatest. Roughly two weeks later the moon is at apogee, which is its farthest point from the earth for the month. That’s when the moon’s influence is at a minimum. During the course of the month, daily inequalities between successive high or low tided also can occur: This happens as the moon moves from about 28 degrees north of the equator to 28 degrees south. When the moon is at one of these extremes, the difference in height between morning and evening tides is greatest. When the moon is at the equator, tides are roughly equal.

The tidal range also increases in January: That’s when the earth’s elliptical orbit around the sun brings the planet closest to the sun, in what astronomers call the state of perihelion. In July, when the earth is farthest away from the sun in what astronomers refer to as the state of aphelion, the tidal range decreases. The shape and depth of ocean basins change tidal ranges, too: The smallest differences in the heights between high and low tides occur along ocean coasts. For example, spring tidal ranges (near the time of the new and full moon) vary from about 2 feet on the Gulf Coast to as much as 8 or 9 feet on the California Coast.

The largest tidal ranges are found in tidal inlets, estuaries, and salt marshes. The Bay of Fundy in Canada has the greatest difference in the world between high and low tide. There, the funnel-like opening of the bay concentrates the energy and increases the height of the incoming tide, resulting in average tidal ranges of about 45 feet. Meteorological conditions can also disrupt normal tide patterns: While tide tables provide accurate times and heights of high and low tide, strong and persistent winds and the low atmospheric pressure associated with storm systems can alter the time and height of high or low tide.

If you are planning to go clamming or to collect seashells at low tide and there is a strong onshore breeze, you may want to delay for as long as an hour after the predicted time of low tide. Horizontal water movements, known as tidal currents, are generally strongest midway between high and low tide: When the tide rises and water flows in to fill estuaries and inlets, the water is called a flood current. When the tide goes out and water drains from these coastal areas, the flow is called an ebb current. Slack currents are found around the time of both high and low tide.

Surf fishing is best done when tidal currents are strongest: Strong flood currents force bait fish up closer to the beach and cause from to school up tighter and hide behind features such as rocks or jetties. Game fish such as bluefish or striped bass take advantage of these conditions, and so should knowledgeable surf fishermen, advises marine fisheries biologist Gregg Skomal. Game fish lie in wait for the bait fish to be swept in and out of inlets, estuaries, and bays by flood and ebb currents. Slack water is usually the worst time to fish. Boaters shouldn’t rely on the tidal charts in coastal newspapers. While most coastal newspapers list the times and heights of high and low tide, boaters need more tidal information than the newspapers provide in order to ensurer safe passage over the ocean floor and to know here to anchor. They should consult the tide and tidal current tables published each year by the government.

The Moon and Tides

The tide is the rise and fall of water throughout the earth’s oceans. Every 12 hours and 26 minutes, tides are created primarily by the moon’s pull of gravity on the water. When the earth is nearer the moon, water is pulled toward the moon, producing a high tide. This happens on the opposite side of the earth at the same time. Spring tides occur when the sun and the moon are directly in line. The moon is either in front of or behind the earth. This produces a very high tide twice a month. Neap tides do not rise as high as normal because the moon is at right angles to the sun. A neap tide occurs twice a month.

Safety for Swimmers and Surfers

Lifeguards recommend swimming off sheltered beaches such as those found in coves or behind a point or peninsula. Swimming is easiest out beyond the breakwaters and away from where the biggest sets of waves are breaking. Eyeball how longshore currents are flowing by watching floating debris or swimmers, and swim with the current to limit fatigue and frustration.

Many years ago Karl Tallman, a lifeguard for the California Department of Parks and Recreation gave these additional tips:

• Spilling breakers provide body or board surfers with the longest ride. Such waves commonly occur on relatively flat beaches and are characterized by foam and bubbles that spill down the front of the wave.
• Plunging breakers can break with great force right on top of an unsuspecting surf swimmer. They are found on moderately steep beaches. The crests of these waves curl over a pocket of air and result in splash-up. As waves, they are short-lived and are not the best for surfing.
• Surging breakers slide up and down the beach creating very low challenges for the surf swimmer. They occur on steep beaches and produce little or no bubbles.
• Rip currents can endanger even the most experienced swimmer. Remember to swim parallel to the shore to escape the current or allow it to carry you out to where its strength diminishes.

Expert choice: To obtain the tide and tidal current tables for your coastal region, contact National Oceanic and Atmospheric Administration Distribution Branch.

Academic Attack 3: Estimated Betas Are Unstable

Academic Attack 3: Estimated Betas Are Unstable

Another problem the theory encounters is the instability of measured betas. One might well be skeptical about the wisdom of relying on beta estimates based on historical data. Beta really looks suspiciously like a tool of technical analysis in academic dress – a bastard cousin of the technicians' charts. And as far as individual securities go, historical betas – used as a basis for predicting future betas and, hence, expected security returns – do not seem to be much more reliable as predictors of security performance than any of the devices cooked up by technical analysis.

In order to see how beta familiarity breeds contempt, we should know how beta is bred in the first place. The typical procedure in estimating betas for an individual stock is ti measure the relationship between the security's past return and the return from the market as a whole. For example, suppose that in the last quarter AT&T's total return (including both dividends and capital gains) was 5 percent and the market return (similarly measured) was 10 percent. We plot this pair of returns on a graph, as is done next.

We can continue the process by measuring the rate of return for AT&T and for the S&P 500 (our proxy for the market) in many other past three-month periods, and we can plot these observations on the same graph. After many pairs of returns for AT&T and for the market have been plotted, a line of best fit (a regression line) is drawn to represent the average relationship between the returns from AT&T and those from the S&P 500 (The regression line is also called a least-squares line, since it is estimated by finding the line that minimizes the sum of the squared vertical distances from each of the black dots to the line). The slope of the regression line (i.e., the ration between the vertical and horizontal sides of a right triangle having the regression line as its hypotenuse) is our measure of the security's historical beta. In this example, we get a beta estimate for AT&T of ½, or 0.5, as shown in the chart. This means that AT&T has been about half as volatile as the overall market, and the assumption is that it will continue to be so in the future. It is clear why this last assertion may be wrong. After the divestiture of 1983 and with deregulation of the telecommunications industry, AT&T is not the same company as it previously was. Even without such major changes affecting the characteristics of the company's stock, some unforeseen event(s), not reflected in past returns, may decisively affect the security's future returns.

Elk. Photo by Elena

To illustrate this hazard in measuring an individual stock's beta, consider the following example : During some periods in the 1960d, Mead Johnson and Company (now part of Bristol-Myers Company) had a measured beta that was negattive; it tended to move against the marker, and thus appeared to be preceisely the kind of stock investors would seek to reduce the risks of their portfolio. But looking behind the reasons for this measured beta's being less than zero did not give one very much comfort that the beta for the future – which is after all what is really relevant – would turn out to be anything like the beta from the past.

What happened in the Mead Johnson case was that in 1962 the company came out with a marvelous new product that became an instant best-seller. The product, called “Metrecal,” was a liquid dietary supplement. Consumers were urged to have a can of Metrecal rather than their normal lunch. Metrecal would provide all the vitamins and nutrients needed for health with few of the calories that usually went along with lunch. An so, in 1962, as Americans became more diet-conscious, drinking Metrecal became quite a fad, and the earnings and stock price of Mead Johnson climbed sharply at precisely the time the stock market was taking one of its worst baths since the Great Depression.

Like most fads, the Metrecal boom did not last very long; by 1963 and 1964, just when the general stock market was recovering, Americans got pretty sick and tired of drinking Metrecal for lunch, and the big boost in earnings and stock prices that Mead Johnson had earlier enjoyed began to fade away.

Later in the 1960s, just about the time the market took another slump, Mead Johnson came out with another new product. This one was called “Nutrament.” Nutrament was a dietary supplement that was supposed to put on weight, and skinny teenagers bought it by the case to improve their appearance. Yes, you guessed it! Nutrament was the same product as Metrecal except that if you drank Nutrament in addition to lunch you could put on weight, rather than lose it. Again, Mead Johnson prospered while the market slumped, and it is this unusual combination of circumstances that produced the negative betas of the period.

The problem is, of course, whether such a fortuitous string of events could reasonably be anticipated to occur in the future. On a priori grounds we would expect not. Indeed, what was in fact measured was anything but a systematic relationship with the market. Of course, this is precisely the problem in predicting betas on the basis of past experience. Any changes in the economy, in the characteristics of an individual company, or in the competitive situation facing the company can be expected to change the sensitivity of the company's stock to market fluctuations. It would be surprising to discover that betas of individual stocks did not vary widely over time. In fact, they do vary. The Mead Johnson example is not just an isolated case, the exception that tastes the rule.

Marshall Blume, a professor at the Wharton school of Finance, conducted several tests of the stability of historical beta estimates. He found that the smaller the number of securities in the portfolio, the weaker the relationship between portfolio betas for consecutive periods. For a portfolio of one security, the earlier beta is a very poor predictor of the beta in the second period. Past betas are not useful predictors of future betas for individual stocks. Better productive power is obtained from betas calculated for portfolios containing larger number of stocks. Thanks to the law of large numbers, the number of inaccurate beta estimates on individual  stocks can be combined to form a much more accurate estimate of the risk of the portfolio as a whole. While the beta estimates for some securities will be much too high, the estimates for many others will be too law.

Mutual-fund betas are not quite as easy to predict from period to period as are betas for unmanaged portfolios, because fund managers will often deliberately change the risk composition of the portfolio. Still, the general investment objective of the fund (e.g. growth, stability, etc.) does put a limit on the degree of change possible, and mutual fund betas also tend to be far more stable from period to period than are the betas for individual stocks. Still, the general conclusion that should be drawn from this discussion is that historical betas may be quite imperfect indicators of future betas. The people who oversold beta as a useful tool in predicting the behavior of individual stocks did the new investment technology a great disservice. In judging risk, beta cannot substitute for brains. Many beta boomers, however gone to great lengths to legitimize their technical bastard.