Teaching space science: methods and approaches

¶ … teaching space science. There are various complexities that affect the way that astronomy is taught, not the least of which is the enormity of scale that space science involves.

One of the basic requirements for understanding astronomy is coming to terms with the vastness of the universe. For example, a basic unit of astronomical measurement is the light year. Merriam-Webster defines the light year as "a unit of length in astronomy equal to the distance that light travels in one year in a vacuum or about 5.88 trillion miles or 9.46 trillion kilometers" (2011). While this definition conveys factual data, it does little to make the concept real, that is, accessible to the average student.

Moreover, trying to convey the reality of light traveling at the unimaginably fast speed of 299,792 kilometers per second (186,282 miles per second) is indeed mind-boggling. Even at such amazing speeds, light takes years to travel to us from the stars, and takes thousands or even millions of years to travel the depths of space between galaxies. When dealing with those kinds of distances it is easy to understand thinking of them as being beyond the grasp of the average individual. To make these quantities more manageable requires putting them into the context of a well-understood frame of reference; doing so helps them to have more meaning (Discovery Education, 2011).

Another challenge for students is being able to relate to how the body of knowledge that makes up modern astronomy has been accumulated. This scientific process has been impacted by many constraints, not the least of which is scientists having to study the universe notwithstanding the fact that they are grounded here on Earth. This limitation affects our ability to understand where we fit into the universe.

Visual biases resulting from this limitation led to misconceptions that persisted in the field of astronomy for centuries. The Earth-centered universe dominated Western thinking for nearly 2000 years, influencing not just astronomy, but philosophy, theology and other disciplines as well. Such misconceptions lingered until the 16th century when Copernicus proposed a heliocentric system. Even then, the Copernican system did not gain widespread acceptance immediately, in part because it contradicted what astronomers believed they had observed (University of Tennessee, n.d.).

Likewise, the physics of light impacts our knowledge of the universe as well. The light that we see from faraway objects travels immense distances across the vastness of space, but at the same time how we see it is affected by the object's brightness.

Astronomy and astrophysics professor Angela Olinto points out another challenge in teaching space science, which is being able to clearly define the boundary between what cosmologists know and don't know about the universe. Scientists have learned quite a lot about what happened from 10 billionths of a second after the big bang to today, 13.7 billion years later. However scientists still do not know what 95% of the universe is made of, nor do they know what happened before 10 billionths of a second after the big bang (Koppes, 2011).

Bennett (1999) offers solutions to the challenge of presenting ideas of scale in such a way that gives students some perspective. He argues that merely telling students about astronomy in terms of numerical relationships is ineffective for students with weak mathematical skills. Bennett suggests instead an approach that compares astronomical scales to familiar scales. For example, the number of stars in the observable Universe is of the order 1022. One way to give meaning to this number, and at the same time help students develop a contextual framework for the enormity of the Universe is to have students imagine counting grains of sands on the beach. Even with the vast sum that would result from this exercise, this is a smaller number than the quantity of stars in the observable Universe. For temporal comparisons, Bennett prefers using Carl Sagan's device of the cosmic calendar, in which one imagines the history of the Universe from the Big Bang to the present, compressed into a single year (Bennett, 2011).

Another means of helping to convey broad spatial and temporal scales needed to understand space science is to have students review their school's "galactic address," an exercise that begins with the school's street address and ends with its place in the universe.

For example, a room within a house would typically be measured in feet, and an example might be 10 ft X 14 feet.

Distances within a city might be measured in miles or fractions of miles, and an example might be driving a half mile to the grocery store, or the town might be about 10 miles wide.

A state might be tens to hundreds of miles across, an example would be the state of Texas is about 600 miles across.

The United States might be measured in hundreds to thousands of miles; the distance from New York to Los Angeles is 3000 miles.

The Earth is measured in tens of thousands of miles; its circumference is 25,000 miles.