Essay Topics

University of Minnesota

Department of Astronomy

Essay 1: Cosmic Impacts


The purpose of this essay is to assess the threat of meteorite impact.

A. How has the rate of impacts changed over the course of Earth's history? Discuss the evidence that scientists use to support this theory.

B. Now consider the danger to
1. yourself as an individual,
2. to the Twin Cities metropolitan area, and
3. to all human life on earth.
For each case, determine the chances (per year) of a destructive impact, and compare with other possible disasters.

C. Using the rate of impacts and the potential costs, try to estimate an appropriate annual budget for an "insurance policy" program to find and divert potentially threatening asteroids.

Some suggested references:

National Optical Astronomy Observatory Press Release, February 2003
Astronomy Magazine, February 2002, "Target Earth".
Australian Spaceguard Survey
Impacts and Defense Strategies (notes from an interesting organization called P.E.R.M.A.N.E.N.T.)
NASA Asteroid and Comet Summary Site (good list of current and planned missions)
Near Earth Asteroid Tracking (see FAQs for overview, plus other good links)
Near Earth Object Report (Task Force findings and recommendations for UK)

Essay 2: Energy Sources

A major concern for the future of our energy-hungry civilization is the use of fossil fuels. Many alternative energy sources have been the subject of considerable study and use, such as wind power, geothermal power, and the expanded use of nuclear power. One reliable, nonpolluting source of energy here on the Earth is light from the Sun. At noon on a sunny summer day in Minnesota, about 1 kilowatt per square meter of sunlight power strikes the ground. One kilowatt is 1000 joules of energy each second. A hairdryer typically uses about 1 kW. The typical American home uses on average 800 KWH (kilowatt-hours = kilowatts x hours = total energy consumed) each month. A hair dryer run for a full hour would consume 1 KWH of energy.

1. About how much energy (in Joules) from the Sun strikes the roof of a typical house each second on a sunny summer day near noon?

2. Estimate the power your roof will receive from the Sun averaged over the course of a year, given that there is nighttime, clouds, and the Sun is not always up high (at noon) in the sky.

3. Find the cost of using photo voltaic cells to generate electricity from Sunlight. These cells are only about 15% efficient! Estimate the cost of outfitting your house to be completely run by solar power.

4. Given the economics of converting your house to solar power, is solar power a viable alternative to our current energy sources at this time? What factors would have to change to make solar power economically viable?


Some suggested references:

U.S. Dept of Energy: Solar Energy
American Solar Energy Society
Yahoo Directory Listing
Solar Electric Power Association
Go Solar Power


Essay 3: Life in the Universe

Ten thousand years ago, the inhabitants of planet Nnim, circling an F8 star which resides in the Milky Way galaxy, launched their first scout ship in preparation for a program of interstellar colonization. On November 14, 2003, that ship encountered a violent storm as it entered Earth's atmosphere and crashed in the Mojave Desert. There were no survivors.

After the wreckage had cooled down sufficiently, Earth scientists sifted through the debris and found a titanium case. The case was carefully opened and found to contain sheets of an almost translucent metallic substance covered with detailed markings that defied translation for many years. On November 14, 2023, twenty years to the day from the crash, an international team of linguists and cryptologists made the joint announcement that the sheets were the ship's journal.

Your essay assignment is to write an excerpt from that journal. Although the story line is fictional, the science must be correct and reflect our current best understanding of the issues. The technology used on your spacecraft can be either what is available today, or future technologies as envisioned by experts today. You may not use unrealistic inventions such as Star Trek's "Warp Drive". As in other essays, material derived from outside sources must be referenced.

The journal must include substantive and scientifically accurate material on the following three topics:

A. The method Nnim scientists used to discover planets around other stars. Why Earth was selected as a candidate target planet, while many other planets were rejected.

B. Considering the distance between Nnim and Earth, describe the most notable astronomical objects and phenomena that the ship's crew encountered during their journey from Nnim to Earth.

C. As the ship approached Earth, the crew made careful measurements of their target planet, and compared these to the original data obtained when the Earth was first chosen as a target, ten thousand years ago. Describe the scouting party's new assessment of the suitability of Earth for colonization, remembering that humanity has had a significant effect on the Earth's environment.