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What you need to know for 08/22/2017

Science keeps evolving as observations are corrected

Science keeps evolving as observations are corrected

Progress in a scientific field can begin with someone just being curious about some aspect of nature
Science keeps evolving as observations are corrected
This 2006 illustration based on images gathered by the Hubble Space Telescope shows the largest-known Kuiper Belt objects. Xena is slightly larger than Pluto, once considered a planet.
Photographer: NASA

It can be easy to look back over the roughly 3,000-year history of science and astronomy and see where our predecessors made some unfortunate mistakes that delayed the advancement of science.

When long-held beliefs or assumptions were not questioned and rigorous experiments and observations were not carried out, science did not progress. Regrettably, it did not move forward for almost 1,500 years.

Science can be difficult to define. In Latin, scientia means “knowledge” but not all knowledge is science. Further, science tends to be a process characterized by critical thinking and reasoning.

For example, if your flashlight stops working, you might reason that the batteries need to be replaced. If you replace the batteries and the flashlight works, then your reasoning has proved to be correct. However, if the flashlight still does not work, then that observation needs to modify your reasoning: Are the new batteries bad? Is the bulb burned out? Is the switch making contact?

Sometimes we are taught in early science courses about the scientific method — an orderly, logical methodology — that can lead us to think that this is how scientists perform science. In reality, science does not always progress in such a systematic and efficient manner. Progress in a scientific field can begin with someone just being curious about some aspect of nature or questioning the prevailing paradigm — the establish set of ideas.

Question everything

Since the time of the ancient Greeks until Nicholas Copernicus in the 16th century, it was generally accepted that the celestial objects orbit around Earth in perfect circles. Copernicus shifted the paradigm to the sun-centered viewpoint but mistakenly retained the idea of circular orbits.

It took the inspiration of Johannes Kepler during the 17th century, mathematically analyzing the observations of the motion of Mars made by his mentor, Tycho Brahe, to break away from the idea of circular paths to that of out-of-round, elliptical orbits.

When Galileo first pointed his telescope at the night sky, he was being inquisitive; he was not looking for anything in particular. Yet, he found moons around Jupiter, spots on the sun’s surface and mountains on the lunar face. He saw that Venus went through phases and that the Milky Way was populated with stars. These were observations of objects and phenomena that no one suspected, but then needed to be explained.

Technology needed

One of the more subtle reasons the ancient Greeks did not think that Earth went around the sun is that they did not observe something called parallax. If you hold your thumb out at arm’s length and blink your eyes back and forth, you will see that your thumb “jumps” from one side to the other against the background.

The ancient Greeks correctly reasoned that if Earth went around the sun, then after six months when Earth was on the opposite side of its orbit, they should see a shift in the position of the stars. Their reasoning was correct but their technology was not there. The parallax angles that the stars shift through are so small that parallax was not discovered until 1860. It was then that the mathematical physicist and astronomer Karl Frederick Bessel used a telescope and found stellar parallax. This effect cannot be seen by the unaided eye.

In addition, technology led to the reclassification of Pluto and the first working definition of a planet. During the 1990s, a research group of astronomers used one of the world’s largest telescopes and began to find objects beyond Pluto. These objects are called Kuiper Belt objects because they were proposed to exist by Gerard Kuiper, a University of Chicago astronomer during the 1950s. Since these objects are small by astronomical standards and so far away, it took modern, huge, light-collecting telescope “buckets” to find these exceptionally faint objects.

Chance for science

Southwest of the Capital Region during the night of March 19-20, a quick, but very rare astronomy event will occur. The asteroid Erigone (Eh-RIG-uh-nee), will pass directly between the star Regulus, the brightest star of Leo the lion, and Earth. This event can only be seen along a very narrow track on Earth’s surface. For 14 seconds, Regulus will “wink out” as the shadow of Erigone falls on a limited part of Earth. In a sense, it is an eclipse of a distant star; an event astronomers call a stellar occultation.

Although these events are fairly common with faint stars, it has only happened once before with a bright star and coincidentally, that star was Regulus.

The “eclipse” track will move across New York City, then upstate through central New York and finally into Canada. It has been estimated that 20 million people could potentially see this event.

Locally, the asteroid’s shadow will pass southwest of the Albany area. The Landis Arboretum in Esperance, observing spot of the Albany Area Amateur Astronomers, will be near the edge of the shadow line.

It is an opportunity for the nonscientist to make an important observation in astronomy. By carefully timing when Regulus disappears and then reappears, a very precise outline of Erigone can be built up by observers spaced across its shadow corridor, and since we know the distance to this asteroid, its size can be calculated.

Ideally, the best timings come from recording the event with a video camera and placing a very accurate time stamp on each video frame. The same can be done with a DSLR camera in video mode while recording time signals from the shortwave radio station WWV on the camera’s audio track.

Alternatively, just shouting into an audio recorder when you see Regulus disappear and reappear with WWV signals in the background can be helpful. The International Occultation Timing Association will collect these observations for analysis (www.occultations.org/Regulus2014).

The bad news: this event occurs at 2:07 a.m.

Richard Monda is an astronomer living in the Capital Region.

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