Popular Misconceptions

Popular Misconceptions in Astronomy

Instructions: MISCONCEPTIONS are in capital letters followed by a colon.
Scientific explanations or discussions follow.

-- PLANETS --

JUPITER WILL BECOME A STAR ONE DAY:

Based upon current theories of stellar formation, Jupiter would need to become about 69 times more massive to evolve into a star. Put in another way, 69 Jupiter-like planets would have to be dumped into Jupiter in order for there to be sufficient material to create the internal temperatures and compression to allow thermonuclear fusion to take place. Jupiter is destined to continue slowly cooling like it has been for the past five billion years since its formation as the largest planet in the solar system. Incidentally, the least massive of stars, about 70 times the mass of Jupiter, would have a breadth slightly smaller than Jupiter’s diameter.

THE JOVIAN PLANETS HAVE SOLID SURFACES/THE JOVIAN PLANETS ARE GAS GIANTS:

The Jovian, Jupiter-like planets, which also include Saturn, Uranus, and Neptune have extensive gaseous atmospheres which eventually become compressed into liquid oceans of primarily hydrogen and helium. As pressures increase, hydrogen is even forced into a metallic state which is the basis for creating the strong magnetic fields which surround all four Jovian worlds. It would be much better to describe these planets as liquid worlds with extensive gaseous atmospheres.

-- THE SUN --

IT IS DANGEROUS TO LOOK AT DURING ANY ECLIPSE:

The word "eclipse" means to hide. During a solar eclipse, part or all of the sun is hidden by the moon. In a lunar eclipse the moon is hidden in the shadow of the earth. A solar eclipse is dangerous to view when any portion of the sun’s light-emitting surface, called the photosphere, is visible to the eye. However, during the totality segment of any total solar eclipse, the moon’s greater apparent size hides the sun’s photosphere completely, allowing visual inspection of the eclipsed sun with the unprotected eye or through telescopes or binoculars. The dangers of viewing the sun when no eclipse is occurring are even greater than viewing a partially eclipsed sun because the entire disk of the sun is visible. However, more people are apt to want to view the sun during the partial phases of a solar eclipse because interest in observing the eclipsed sun is high. On the other hand, viewing the moon during a lunar eclipse poses no danger whatsoever. Observing the full moon is not dangerous with the eye or with instrumentation. Observing the full moon entering the earth’s shadow during a lunar eclipse is equally safe.

THE SUN WILL EXPLODE AT THE END OF ITS LIFETIME:

The sun may be considered to be a typical star, five billion years of age, about midway through its life. At present it is converting hydrogen into helium in its core and will continue to do so for the next five billion years. As fusion continues, the accumulation of helium ash in the sun’s interior will cause the core to contract slowly and increase in temperature, thus augmenting the amount of hydrogen burning in the core. This will cause the sun to become slightly larger, cooler, and more luminous. Near the end of its existence hydrogen burning will cease in the core and shift to a thin shell surrounding the sun’s center where fusion will continue supplying the core with ever more helium ash. This additional material will shrink the core making it even hotter and expanding the sun into its red giant phase. At this time the sun will probably become variable, due to instabilities generated in its thin hydrogen burning shell. These instabilities will eventually cause the sun to shed its outer layers to reveal its inert, hot interior composed primarily of helium. At this point the sun will be called a white dwarf star. Its diameter will be approximately 10,000 miles.

SUNSPOTS ARE STORMS ON THE SUN:

In one way sunspots are storms, but not in the traditional sense of peoples’ conceptions of storms. They have nothing to do with any meteorological effects which may be occurring on the sun. Sunspots are very quiet regions on the sun’s "surface," which is known as its photosphere. Here the convective mechanism for releasing the sun’s heat has been slowed. The region called the sunspot has become cooler, thus making it appear darker against the brighter, hotter photosphere. What has caused this is an intense magnetic field which has affected the outward flow of plasma in the sunspot’s vicinity, thus causing the cooling and darkening of the area. In a very real sense, the high magnetic fields associated with spots could be called a magnetic storm. It is in the vicinity of sunspots that other magnetically induced phenomena occur, such as the arcuate filaments of plasma that form in the sun’s corona, known as prominences, or the extremely energetic flares which can produce intense auroral displays on earth and disrupt the transmission of electricity.

-- THE STARS AND CONSTELLATIONS --

POLARIS, THE NORTH STAR, IS THE BRIGHTEST STAR OF THE NIGHTTIME SKY:

Not so... It actually ranks as the 49th brightest star in the heavens, if the sun is included. Polaris is relatively easy to spot even from an urban locale, but its real importance stems from the fact that its position is near the place where the earth’s axis intersects the heavens. As a result, the earth’s rotation causes the heavens to appear to wheel around this star, making it an excellent marker to determine the direction north. The brightest star of the nighttime sky is Sirius, the Dog Star. Follow the three stars of Orion’s belt downward to this gem of the winter sky

POLARIS HAS ALWAYS BEEN THE NORTH STAR:

Because the earth’s axis wobbles like a top, completing one (precession) cycle during a period of 26,000 years, the direction in the sky where the axis points, slowly changes. At present, the axis projects very near to the star Polaris, but 5,000 years ago, when the Great Pyramid at Giza, and Stonehenge I were being constructed, the earth’s axis pointed fairly close to Thuban, a star in Draco, the Dragon. About 12,000 years into the future the earth’s axis will be directed towards the star Vega, in the constellation of Lyra, the Harp.

THE BIG DIPPER IS A CONSTELLATION:

The star pattern going by the phrase, "The Big Dipper" is only known by this name to Americans. It is called the Plow in England, and the Wagon in Germany. During the Civil War, slaves escaping the South through the network of safe havens known as the underground railroad, referred to the Dipper as the Drinking Gourd. Its location is always found in the northern part of the sky, so the Drinking Gourd made an easy marker to follow as blacks made their way north to freedom. The Dipper is really an asterism, a group of stars which form a picture, but which has not been officially recognized by professional astronomers as a constellation. Ursa Major, the Great Bear, is the official name of the constellation which Americans refer to as the Big Dipper. The Great Bear is difficult to see from urban locations, so the Big Dipper has continued to remain more popular in this country than the official constellation.

CONSTELLATIONS ARE GROUPINGS OF STARS IN THE SKY WHICH FORM PICTURES:

Constellations are very much like states with official borders. Within these boundaries certain stars may be found to form a picture, but all stars within the boundary are considered members of the constellation. There is no official strategy with regards to how the stars of a particular constellation are to be connected to form a picture. Eighty-eight constellation boundaries encompassing the entire sky were sanctified in 1928 by the International Astronomical Union, a world-wide congress of professional astronomers. Constellations are useful to modern astronomy because they allow an approximate location for knowing where objects in the sky can be found.

ALPHA CENTAURI IS THE CLOSEST STAR TO THE SUN:

The Alpha Centauri system is the closest stellar system to our sun. What we perceive as Alpha, is really a double star with its two components, 1 and 2, separated by about 17 seconds of arc. About 2.2o away from Alpha lies very faint Proxima Centauri, also thought to be part of the Alpha Centauri system and currently on the sunward side of its orbit. Therefore, technically, Proxima is the closest star to our sun. Its distance is about 4.26 light years or 25 trillion miles. Proxima is 0.11 light years closer to the sun than Alpha Centauri 1 and 2, giving it an orbital period around this pair of about one million years.

STARS ARE BURNING HYDROGEN:

Although it is customary for astronomers to use the words "hydrogen burning" in connection with the energy producing mechanisms inside of stars, nothing could be farther from reality. Combustion is a chemical process which releases energy. The atoms which partake in the reaction are not changed in any way because of the reaction. The "burning" which takes place inside of stars results in the creation of new atoms through a process called nucleosynthesis. In the sun, four hydrogen protons are fused into one helium nucleus. The process is more complicated then that, but the concept is valid. In the fusion of four hydrogen protons some mass is converted into energy as helium atoms are created. This is the mechanism which powers most of the stars that we see in the sky.

-- SPACEFLIGHT --

THE FIRST AMERICAN IN SPACE WAS JOHN GLENN:

Alan Shepard rode his Freedom 7 capsule into a suborbital flight to become the first American in space on May 5, 1961. Shepard later walked on the moon during the Apollo 14 mission in late January 1971. John Glenn was the third American (fifth human) to venture into space, but the first American to orbit the earth. He is now a US Senator from Ohio. On both counts the US was upstaged by the Russians who placed a man in space and in orbit first. The first human to venture into space was the Russian, Yuri Gagarin aboard Vostok I on April 12, 1961. He also was the first human to orbit earth during the same mission which lasted 1 hour, 48 minutes.

THE SPACE SHUTTLE CHALLENGER BLEW UP:

From the video footage it may have looked like an explosion in the traditional sense, but there was no combustion (fire). What occurred was a failure of an O-ring on one of the two solid fuel booster rockets. The O-rings held together the sections of the cylinders which in total made each of the two reusable boosters. Rapidly escaping gases from a malfunctioning O-ring dislodged one of the booster rockets, sending it into the huge liquid fuel tank on which the shuttle rides during its ascent. Once this tank was ruptured, rapid expansion of the liquid hydrogen and oxygen, ripped apart the shuttle sending the seven crew members to their deaths. The crew was probably alive, but unconscious when the virtually intact crew cabin impacted into the Atlantic Ocean several minutes after the catastrophe.

-- GRAVITY AND RELATIVITY --

ISAAC NEWTON INVENTED GRAVITY:

Isaac Newton (1642-1727), the great English physicist, never invented gravity. Gravity was always around and is a condition of any object which possesses mass. Newton was the first person to explain accurately how the force of gravity acted upon matter within our universe. Standing on the shoulders of such eminent scientists as Galileo and Kepler, Newton postulated that the force of attraction between two objects was directly proportional to their masses (the quantity of matter which they contained) and inversely proportional to the square of the distances between these bodies. Mythology recounts that Newton’s inspiration for his idea was triggered by watching an apple fall from a tree at his home in Woolsthorp, England. He wondered whether the same force of gravity that accelerated the apple towards the ground was responsible for holding the moon in its orbit around the earth. His investigations led to the conclusion that they were the same force, and the quantification of gravity resulted.

SPACE, MASS, AND TIME ARE CONSTANTS:

Space (length, width, and height), mass, and time are actually variables. The only constant in the universe is the velocity of light. Traveling at velocities near that of light (186,000 miles/second) would cause our perceptions of the universe to alter. Specifically, a detected object traveling close to the speed of light would appear to be compressed in the direction of motion. Clocks in that object would appear to be keeping time at a slower pace than clocks in the frame of reference of the observer. The mass of the perceived object would also be increased (see below).

IT IS POSSIBLE TO TRAVEL FASTER THAN THE SPEED OF LIGHT:

Only the limitlessness of the human imagination can entreat an object to travel as fast or faster than the velocity of light. For matter bounded by the laws of physics in this universe, an increase in velocity results in an increase in the amount of mass which an object contains. At the velocity of light, the mass of an object becomes infinite. If all of the matter in this universe were converted into energy, there still would not be enough force to accelerate the smallest amount of matter to the velocity of light because the mass-energy of this universe is thought to be finite.

A LIGHT YEAR IS A MEASUREMENT OF TIME:

A light year is a standard astronomical yardstick for measuring the distances between objects outside of our solar system. One light year represents the distance that light travels during a period of one year. This distance is equivalent to approximately 5.8 trillion miles.

-- MISCELLANEOUS --

COPERNICUS WAS THE FIRST PERSON TO GIVE US THE CONCEPT OF A SUN-CENTERED UNIVERSE:

Actually, it was the Greek, Heracleides (388 BC-315 BC) and later, Aristarchus of Samos (310 BC-230 BC) who first entertained the heliocentric notion that a rotating earth could be in revolution around the sun. The concept lost favor to the geocentric model of the universe which was the synthesis of hundreds of years of inductive reasoning practiced by Plato, Eudoxus, Aristotle, Hipparchus, Ptolemy and others. The Greeks never intended their ideas to represent reality, but by the time of the Renaissance, Ptolemy’s geocentric model was thought to portray accurately the true order of the cosmos. Copernicus realized the inexactness of the cumbersome geocentric models to predict accurately planetary positions and borrowed ideas from earlier Greeks to simplify the system into a heliocentric version. However, Copernicus did not merely suggest this change, he worked out the mathematical details of this system to show how the revolutions of the planets around the sun could account for the observations of planetary motion. Ironically, after Copernicus completed publication of his theory in 1543, under the title of De Revolutionibus Orbium Coelestium astronomers could not decide by observations which theory produced the better fit. It appeared that the simplicity of the Copernicus’s theory easily began to win converts, particularly in the Protestant territories of Europe. The dilemma of which theory was superior was finally solved by Johannes Kepler in 1609 when he used the Copernican model to solve correctly for the changes which Tycho Brahe had observed in the positional shifts of the planet Mars. When Kepler used ellipses to explain planetary motions, rather than the circular motions which Copernicus had retained in his theory, Tycho’s data fit precisely with the orbital parameters of Mars. In short order, the reinvented heliocentric theory as proposed by Copernicus became one of the cornerstones of Renaissance thought.

Return to the astronomy links menu