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Asteroids

First Calvin discoveries to receive names: Asteroid 128177 Griffioen and 129099 Spoelhof

What event has just occurred?

What does it take to get a name?

What is the history of these two asteroids?

Why were these specific names chosen?

What is the role of asteroid study in science today?

What is the role of asteroid study in science education at Calvin?

Asteroids Spoelhof and Griffioen

What event has just occurred? Two asteroids discovered at Calvin College have had names officially bestowed upon them (Minor Planet Circular 56963, 2006 June 13). The asteroid provisionally known as 2003 RA11, discovered by Calvin student Andrew Vanden Heuvel, is now named Asteroid 128177 Griffioen, after Roger Griffioen, former dean and physics department chair of Calvin College . And the asteroid provisionally known as 2004 XU3, discovered by Calvin Physics and Astronomy professor Larry Molnar, is now named Asteroid 129099 Spoelhof, after William Spoelhof, longtime president of Calvin College. The image above shows both asteroids as they appeared on December 4, 2004. Click on the image to see a movie of their motion that evening.

What does it take to get a name? When a new asteroid is discovered, it is given a provisional name which indicates the month and year of discovery plus a number to make the name unique. However, unless the new discovery is followed up on timescales of weeks, months, and finally years, its orbit cannot be determined well enough so that in the future it can be located again and distinguished from other asteroids. Therefore a permanent serial number and name is not assigned until the asteroid has been well observed over four oppositions. An opposition is the relatively close encounter between the asteroid and Earth as the Earth laps the more slowly moving asteroid every year or two in its continual motion around the Sun.

What is the history of these two asteroids? Asteroid Griffioen was discovered on September 5, 2003 by Calvin student Andrew Vanden Heuvel with the then-new telescope in the dome on the Science Building . (See the discovery images.) It occurred serendipitously in the course of studying a different asteroid, one named van den Heuvel after a famous Dutch astronomer.

By combining Andrew's observations with observations made by other observatories that month, the Minor Planet Center was able to determine a preliminary shape to the orbit. Extrapolating backwards in time, they were also able to find isolated observations from a previous opposition and put them together for a more refined orbital solution. Then we had to wait until December 2004 to see if it could be recovered again at or near the predicted place. On December 3, Professor Larry Molnar found it using Calvin observatory in Rehoboth, New Mexico, which had just been commissioned that year. The position and motion of the asteroid matched the prediction beautifully. (See the recovery images.) Finally, Molnar recovered it again at its most recent opposition this past January. Having the requisite four oppositions, it was assigned its permanent serial number, 128177, in March.

Just as Asteroid Griffioen was found serendipitously in the pursuit of another asteroid, Asteroid Spoelhof was discovered on December 3, 2004 in the same set of images that contained the first successful recovery of Asteroid Griffioen. Molnar continued to track it until January 13, 2005. That span of data enabled a preliminary orbit determination, and the finding of prediscovery images from two previous oppositions. Therefore, only one more recovery was needed to complete the orbit determination. It was observed by six different observatories (including our own Rehoboth telescope) at the most recent opposition from last December through March. With its orbit now secure, it was assigned its permanent serial number, 129099, in March as well. (See animated orbits from the NASA web tool for both Griffioen and Spoelhof. Or for current position, distance, and brightness of either object, go to the Minor Planet Center Ephemeris page, type the names "Griffioen" or "Spoelhof" in the text box, and click on the "Get ephemerides" button.)

Why were these specific names chosen? Once an asteroid has received its permanent numerical designation, it is the privilege of the discoverer to suggest a permanent name to the committee on nomenclature of the International Astronomical Union (IAU). Vanden Heuvel and Molnar, together with the Physics and Astronomy department chose Griffioen and Spoelhof to commemorate the establishment of the Calvin College observatory in 1970. The formal citations as published by the IAU are as follows:

"Roger Griffioen (b. 1934) served 37 years at Calvin College, including seven years as academic dean and 17 years as physics chair. He built a high-quality physics program, implemented the construction of a college observatory and played a formative role in the lives of many students.

"William Spoelhof (b. 1909) served as president of Calvin College from 1951 to 1976. Among his achievements at this Christian liberal arts college, he fostered the establishment of an astronomy program. This included the construction of an observatory in 1970."

As president of the college during the launch of Sputnik it was clear to Spoelhof that science needed to be taught at the college much more completely than had been the case. At that time, most of the sciences were rolled into one department. In particular, he felt astronomy and geology should be taught as specific topics, with laboratory science as well as lectures. With the development in the late 1960s of the new (and present) campus, these thoughts were put into action with the construction of the Science Building (one of the first to be built). The specifications included space for laboratory work, a loading dock, and an observatory dome on the roof. He approached friends of Calvin about donating the money for the equipment, and the te Velde family granted the college funds for the purchase of a telescope.

In 1970, Roger Griffioen was the first chair of the new physics department, and hired most of the first generation of faculty for the department. He had served on a curriculum committee in the late 1960's commissioned to consider the introduction of astronomy and geology courses. President Spoelhof turned to him to turn the idea into reality: Griffioen oversaw selection of the new telescope and dome and establishment of the first astronomy course, which was taught in spring of 1972.

What is the role of asteroid study in science today? As the tally of numbered asteroids has recently moved into six figures, interest in the field among astronomers and others continues to increase. The bulk of these objects have orbits that lie between those of the planets Mars and Jupiter. Over time, however, the asteroids and their orbits are changed by mutual collisions and by interactions with Mars and Jupiter. The accumulation of interactions on the range of asteroids serves as a ledger on which is written much of the early history of our solar system, the chief reason for academic interest in asteroids as a group. Interest of a much more current sort focusses on the very small minority of asteroids that at any given time have interacted so much with the planets that their orbits now cross that of Earth, so-called Potentially Hazardous Asteroids (PHAs). Significant government funding has gone into cataloging these objects as completely as possible, with the intent of knowing about the next major collision with Earth well enough in advance to avert it.

What is the role of asteroid study in science education at Calvin? Following the intention of President Spoelhof that astronomy should be taught as a laboratory science, Calvin College has recently upgraded its observing equipment. New, computer-controlled telescopes were purchased with National Science Foundation grant money: one replacing the 1970 instrument in the dome on campus, and a second one placed at a dark-sky site in Rehoboth, New Mexico, but run over the internet by Calvin students.

Although these telescopes are used for a wide range of observations, classroom observations of asteroids has been a featured use. Searches for new asteroids have been carried out over four semesters now, and the total of provisional designations assigned to Calvin discoveries is now over sixty. (See the table of Calvin-discovered asteroids and their properties and a description of the classroom exercise.) The goal is to understand better how real science works by aiming for a new discovery. This makes the jump from laboratory exercise to genuine laboratory as all results are submitted for publication in the "Minor Planet Circulars". Students take the labs more seriously knowing the results count for more than just a grade, and the thrill of discovery is the more sweet when neither you nor your teacher know what you will find in advance. And as the number of asteroids found increases, the chances of finding unusual asteroids increases with it. This semester student Josh Vanderhill discovered a Trojan asteroid, the first Calvin discovery of an asteroid outside of the main belt. It is always possible a future student may discover a Potentially Hazardous Asteroid, one that crosses the Earth's orbit. As far as we know, this is the only astronomy class in the world in which discovery of a new solar system object is an assignment.

A second asteroid laboratory was initiated this semester, in which students from the Astronomy 211 class determined the rate of rotation of known asteroids. This is a more time-intensive exercise, but with a greater scientific payoff. Only one in a hundred known asteroids have had their spin measured. But as more spins are determined, scientists are able to determine more of the details of the structure and the collisional history of asteroids. The results from this first run will be submitted to a science journal this summer.

[Text by L. Molnar, posted 6/15/06.]

 

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