Oct. 25 – Once while well-known astronomy lecturer and author by George Lovi (1939-1993) was running a public night at the Brooklyn College Observatory in New York, the telescope was pointed at Venus, displaying a delicate crescent shape. Yes, Venus goes through phases, just like the moon does, as seen from our point of view. A student, surprised by the crescent, stubbornly insisted he was really looking at the moon. Lovi pointed out that the moon wasn't even in the sky that night. "So what?" the student said. "Doesn't a telescope show you things you can't see without it?" This is but one of a number of popular misconceptions in astronomy. Some are widely held, others linger more as confounding questions in the backs of peoples' minds. Here's my own personal list of ten Confounding Cosmic Questions, in no particular order, along with some less confounding answers:

Is a half moon half as bright as a full moon? Why don't comets zoom across the sky? Is July hot because we are closer to the Sun? Why isn't the North Star the brightest star? Why is there no South Star?

Can artificial satellites be seen with the unaided eye? Must I wait centuries to see a total solar eclipse? Why doesn't the equinox occur on March 21st anymore? Why don't meteor showers produce a shower? Can you see through clouds with a telescope?

IS A HALF MOON HALF AS BRIGHT AS A FULL MOON?
It is certainly logical to expect that when the moon is 50 percent illuminated (at first or last quarter phase; also sometimes called the "half-moon"), that it would be shining only half as bright as a full moon. Indeed, if the moon's disk was flat like a white piece of paper or a projection screen, then its surface brightness would be the same all over and this would be true. But of course, this is not the case. The moon is a sphere, and the amount of reflected light from the sun per unit of moon area decreases toward the lunar terminator (the dividing line between the bright and shaded regions). Near and especially along the terminator, mountains and boulders strewn across the lunar landscape cast innumerable shadows. This gives the effect of the moon appearing brightest near and along its edge, but grayer toward the terminator. In contrast, at full moon, the sun is shining straight down virtually everywhere on the lunar surface so that there are no shadows at all. Believe it or not, only about 2.4 days from full moon does the moon shine half as bright as when it's full. And when the moon is at first quarter phase, it is actually only 1/11 as bright as full! At last quarter it's even dimmer – 1/12 – because of the greater visible area of the dark maria (or lunar "seas") on its illuminated portion.

WHY DON'T COMETS ZOOM ACROSS THE SKY?
Before answering this question, think about this: Have you ever seen the moon whiz across your line of sight like a meteor? Even though the moon is traveling around the Earth at more than 2,000 mph (3,200 kilometers per hour), at its average distance of 239,000 miles (382,000 kilometers) from Earth, its orbital motion is barely perceptible. Similarly, although a bright naked-eye comet might be moving at many tens of thousands of miles per hour through the inner solar system, its distance from Earth typically will measure in tens of millions of miles. So while a bright comet will indeed appear to move, because of its distance from Earth, its apparent night-to-night movement against the background stars is very slow. A comet moves across the sky in the fashion of the moon (or the planets for that matter). Not in the fashion of a streaking meteor.

IS JULY HOT BECAUSE WE'RE CLOSER TO THE SUN?
In fact the Earth is at its farthest point from the sun in early July and closest to the sun in early January. The difference in distance from the Earth to the sun between these two extremes is about 3 million miles (5 million kilometers), or 3.3 percent, which makes a difference in radiant heat received by the Earth of nearly 7 percent. Thus for the Northern Hemisphere one might assume that this difference tends to warm the winter and cool the summer. The seasons, however, are not caused by the change in the distance of the Earth to the sun. Rather, they are due to the 23.5-degree tilt of the Earth's axis, which causes various parts of our planet to be turned toward or away from the sun at various times of the year. Summer in the Northern Hemisphere is when that half of the planet ispositioned for longer days and maximum sunlight. The preponderance of large landmasses in the Northern Hemisphere has an effect, too, tending to make winters colder and summers hotter than those of the Southern Hemisphere. Land warms and cools more quickly than water. The Southern Hemisphere has a far greater amount of ocean coverage, which moderates temperatures, helping to make the winters a bit milder and the summers a bit cooler. Here's another way to think about this: In the Northern Hemisphere, when we think of "cold outbreaks" during the wintertime, we think of cold surges of air coming down from Canada or Siberia, where the frigid air builds up. There are no such similarly large land regions in the Southern Hemisphere that can produce comparably large outbreaks of cold air. There are quirks in all this, however. When we compare temperatures of the North Pole versus the South Pole, the South Pole wins because Antarctica is a land-locked continent as opposed to the North Pole, where a similar solid landmass does not exist. But Antarctica is completely surrounded by water, so any frigid air that might originate from it is significantly modified when is spreads out toward Australia, South Africa and South America.

WHY ISN'T THE NORTH STAR THE BRIGHTEST STAR?
When I was a very young boy an uncle of mine took me out on a balmy summer evening, pointed to a brilliant blue-white star directly overhead and said: "See that? That's the North Star" (I later would learn that it was actually Vega, the fifth brightest star in the entire sky). Granted, Polaris, the real North Star, is probably the most important star visible in the northern sky. Yet many people are under the mistaken impression that it's also the brightest. It actually ranks only 49th in brightness and, for most viewers, is not directly overhead. Polaris is the closest bright star relative to the north celestial pole. Only the apparent width of about 1½ full moons separates Polaris from the pivot point directly in the north around which the stars go daily, as seen from any vantage point in the Northern Hemisphere. Interestingly, because of the wobbling motion of the Earth's axis (called precession) the celestial pole will draw even closer to Polaris (closest in the year 2100), but then as time wears on it will gradually draw away from it. In fact, in about 12,000 years our descendants will have Vega as the North Star. My uncle will be happy to hear that.

SO WHY IS THERE NO SOUTH STAR?
Actually, there is a South Star, but unlike its northern counterpart it is a small, faint star. It is Sigma Octantis, in the very dull southern constellation of Octans, the Octant. It is, in essence, the "Polaris of the Southern Sky" (some texts even refer to it as "Polaris Australis"), although at magnitude 5.5, this South Star is only 1/25 as bright as the North Star. Northerners might wonder how those in the Southern Hemisphere find their way around without a bright benchmark near their pole. For that they can rely on Crux, the Southern Cross, whose longer bar points almost precisely toward the south pole of the sky.

CAN ARTIFICIAL SATELLITES BE SEEN WITH THE UNAIDED EYE?
Most definitely they can! In fact, many people are surprised that an object orbiting hundreds of miles above our heads can be readily seen without the use of binoculars or a telescope. From the launch of the first Sputnik in 1957 to the present, the number of satellites in space has grown at a spectacular rate – there are now more than 10,000 good-sized hunks of metal orbiting the Earth, though not all are functional satellites. In fact, the total number of active satellites is about 600. From the days of the old Soviet Union, countless hundreds of discarded rocket casings and cylinders from their Kosmos program alone were left in orbit. Some of these can shine like a moderately bright star. British astronomer Desmond King-Hele once noted that a satellite "looks like a star that has taken leave of its senses and decided to move off to another part of the sky." If you go out and carefully study the sky near dusk or dawn, the odds are that you should not have to wait more than 15 minutes before you see a satellite. Most are too faint to be seen with the unaided eye. But a few hundred are large enough (over 20 feet in length) and low enough (100 to 400 miles, or 160 to 640 kilometers above Earth) to be visible. Satellites are seen at night because they are illuminated by the sun. A satellite entering the Earth's shadow immediately vanishes from view and pursues an unseen path until it again emerges into full sunlight. The International Space Station ("Alpha") and the space shuttle are by far the brightest. Orbiting the Earth at an average altitude of 240 miles (380 kilometers), they can appear to move as fast as a high-flying airliner; sometimes taking about three to four minutes to cross the sky. They can easily be confused with aircraft lights, though at their brightest they can sometimes appear to rival Jupiter in brilliance.

MUST I WAIT CENTURIES TO SEE A TOTAL SOLAR ECLIPSE?
Not if you don't mind doing some traveling. On average, a total solar eclipse is visible about every 18 months somewhere on the Earth's surface. Unfortunately, the tracks of total solar eclipses seem to have this perverse habit of occurring over sparsely populated regions of the Earth or out over the open oceans. The planet is two-thirds water, after all. And even though a typical eclipse track can run for several thousand miles or more, the width of that track is likely to be less than 100 miles. So, the odds are that any one particular spot on the Earth will have to wait a very long time – about 375 years) – between total solar eclipses. But that nearly four-century wait is merely a statistical average. Indeed, the paths of different eclipses sometimes will criss-cross over a specific place, so in some cases the wait isn't so long at all. For example: a forty-mile stretch of the Atlantic coast of Angola, just north of Lobito, experienced a total solar eclipse on June 21, 2001 and will be treated to another later this year (December 4) after a wait of less than 18 months. On the other extreme, we can cite the case of the islands of Bermuda. Their last total eclipse was on August 30, 1532 with the next one scheduled for February 16, 2352!

WHY DOESN'T THE EQUINOX OCCUR ON MARCH 21 ANYMORE?
It doesn't seem right, does it? I mean, when many of us were growing up, the first day of spring, also known as the vernal equinox (in the Northern Hemisphere) was on March 21, not March 20. Now, all of a sudden spring is arriving on March 20. How did that happen? During the 20th century, at the longitude of Greenwich, England, the vernal equinox landed on March 21 no fewer than 58 times (39 times between 1901 and 1951). Yet, in Europe and Asia only the years 2003 and 2007 will see the equinox arrive on March 21. For North America throughout the entire 21st century, the equinox will arrive no later than March 20. And in 2004, for those in the Mountain and Pacific Time zones, spring will officially arrive on March 19! There are several factors to account for the date shift, including variations in our Gregorian calendar, the precession or "wobble" of the Earth's axis and the pull of gravity from the other planets, which (ever so slightly) affects the location of the Earth in its orbit. Interestingly, in the Northern Hemisphere, spring is currently being reduced by approximately one minute per year and winter by about one-half minute per year. Summer is gaining the minute lost from spring, and autumn is gaining the half a minute lost from winter. Winter is the shortest astronomical season. With its seasonal duration continuing to decrease, it is expected to attain its minimum value of 88.71 days by about the year 3500.

WHY DON'T METEOR SHOWERS PRODUCE A SHOWER?
When an announcement is made through the news media about an upcoming meteor shower, it likely will conjure up visions in the minds of many of a sky filled with meteors pouring out of the sky like water from a hose. Unfortunately, in just about all cases, your average meteor shower is far cry from that. Typically, if you're outside on a clear, dark night you might catch a glimpse of perhaps 3 to 6 meteors (popularly called "shooting stars") over the course of an hour's watch. On certain nights, the hourly rate may be somewhat higher, in which case astronomers would say that a "meteor shower" is in progress. In the middle of August or the middle of December for instance, you might notice that meteors are comparatively plentiful; perhaps coming at a rate of about one per minute. Indeed, these are the times of the two best meteor displays of the year, although one would not conclude that a true "shower" was in progress. There are rare occasions, when Earth interacts with a dense trail of dust recently shed by a passing comet, that meteors will seem to literally pour from the sky in shower-like fashion. Unfortunately, such opportunities are few and far between. In recent years, the Leonid Meteor Shower in mid-November has provided us with some spectacular meteor outbursts. While perhaps not falling as thick as snowflakes, Leonid rates reached into the thousands per hour in 1999 and again in 2001. Another spectacular Leonid outburst is due this year – perhaps the last for a very long time.

CAN YOU SEE THROUGH CLOUDS WITH A TELESCOPE?
Not a chance. Although some people believe that a telescope is capable of revealing objects otherwise masked by cloud cover. Here are just two examples. In December 1973, a special gathering was organized in lower Manhattan at dawn to observe the newly discovered Comet Kohoutek. Prospective viewers were invited to view the comet through a variety of telescopes in the pre-dawn hours, followed by a chowder breakfast. On the appointed morning, the sky was hopelessly overcast, yet thousands of people came just the same, many still expecting to get their promised view of the comet – despite the clouds – through the assemblage of telescopes. After an astronomer explained from a sound truck that the comet would not be visible he asked if there were any questions. From out of the crowd somebody asked, "So what do we do now?" To which the astronomer replied: "Have another bowl of chowder!" A year later, in December 1974, a partial eclipse of the sun occurred over much of North America. In New York, local astronomical societies had gathered with their telescopes on the 86th floor observation deck of the Empire State Building. A large number of reporters were also there to report on the viewing of the eclipse. Unfortunately, a solid deck of low, gray clouds completely obscured any possible view of the sun (some attributed the bad luck to the fact that it was also Friday, the 13th)! One reporter for a local news radio station arrived just moments before the predicted peak of the eclipse. He pushed his way through the group and, somewhat out of breath, asked which telescope he could look through to view the eclipse. When it was explained to him that the eclipse couldn't be seen because of the clouds, he was incredulous, saying in exasperated tones, "You mean I came all the way up here for nothing?" But in the end he had the last laugh. Composing himself, he quickly filed his report from a nearby phone booth: "The clouds eclipsed today's eclipse, and this reporter was rather surprised to discover that not even these impressive telescopes could provide us with a glimpse. If you ask me, this is the biggest cover-up since Watergate!"

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