# 2003 - PJAS Astronomy Award Winners

Using Eratosthenes' Method to Measure the Size of the Earth
Jayme Detweiler (St. John the Evangelist)

Project Description:

In my project I used Eratosthenes' method to measure the Earth. I first needed to do research to find out about him, and what his calculations were. I did this and then did my own experiment based on his. My hypothesis was that I would come closer to the size of the Earth than Eratosthenes. To measure the size of the Earth I measured the shadow cast by a pole I placed in my backyard. I then compared it to the shadow measured for a pole in the backyard of my grandmother's house which had to be on the same meridian. I did three trials each day for the next three sunny days, to make my experiment more accurate. After making graphs to display my data I used trigonometry and found the tangent of the shadow angle. I then found the size of the Earth by using a trigonometric equation. After using my results in the equation I found my percent of error. I concluded that my hypothesis was proved correct. I came closer to the size of the Earth than Eratosthenes. I was astounded to realize that by measuring shadows and applying trigonometry you can measure the Earth.

Calculating Solar Differential Rotation
Dan Weber (Keystone Oaks Middle School)

Project Description:

The project I chose is entitled "Differential Solar Rotation". In this experiment I compared the rotation of the Sun to the rotation of a solid sphere. This was done using image processing software and data obtained from the NASA/ESA SOHO satellite. I used these images to follow sunspots across the solar disk from limb to limb at different latitudes. Numerical data of linear velocity was obtained by superimposing the pictures onto a coordinate grid representing equal areas of the spherical surface. Comparing the speed of the empirical rotation to the theoretical speed of a solid sphere, I hypothesized that sunspots located at differing latitudes would rotate more slowly than they would if the Sun were a solid body. My data bore this out. I did this experiment because of the increasing interest in the Sun, the Solar System, and all of outer space.

Substorms, Earthward Plasma Flows, and the Aurora
Katherine Pazamickas (Lourdes Regional)

Project Description:

Space Weather is a phrase that encompasses a broad array of natural physical processes that take place in space, near the Earth. Under certain conditions, the magnetic field lines in the magnetotail will connect or merge, and, like a stretched rubber band when it breaks, release stored energy. My experiment uses the data from science instruments on spacecraft to measure strong bursts of Earthward-moving particles that are called Bursty Bulk Flows or BBF. The questions I've set out to answer are the following:

1. How much energy is transported toward Earth by Bursty Bulk Flows (BBF) in the magnetotail?
2. What form of energy dominates the Earthward transport by Bursty Bulk Flows (BBF): kinetic, thermal, or electromagnetic energy?
3. Is the energy transported toward Earth by Bursty Bulk Flows (BBF) sufficient to power the aurora?

My hypothesis is that Bursty Bulk Flows (BBF) do contain and transport significant amounts of energy that is then released in the aurora. The energy released by magnetic field lines is carried toward the Earth, in the energy of the particles trapped on those field lines. I think the dominant term of energy transport will be electromagnetic energy. The method for testing my hypothesis is to apply spacecraft data to the magnetohydrodynamic (MHD) energy equation. In doing this, I can compare the energy contained in Bursty Bulk Flows of plasma to what is thought to be deposited in the aurora, calculated by Dr. Matthew Fillingim, using POLAR UVI images. The results of this experiment show that BBF do contain and transport significant amounts of energy to Earth. Thermal energy is the dominant term. The magnetic signature of dipolarization was identified in all 15 BBF events. When compared to auroral values, BBF do contain sufficient energy to power the aurora. BBF locations can be linked to the initial brightening of the aurora by magnetic field line mapping, linking the two processes, which can be supported by POLAR UVI images. I can conclude that my analysis supports current theory that BBF are associated with ion heating and dipolarization of the magnetotail. The aurora results from magnetospheric processes, rather than the direct infusion of solar wind particles into the ionosphere.

Delta Cephei: Observations of a Variable Star
Emily Southerton (Mifflinburg High School)

Project Description:

My project tested the period of the variable star Delta Cephei. My hypothesis was that Delta Cephei would follow a steady pattern fluctuating from magnitude 3.6 to 4.2 in roughly a five day cycle. The following is a summary of the method I used to collect data on Delta Cephei. Every 24 hours, weather providing, I would observe and record the magnitude of Delta Cephei. I would find the magnitude of Delta Cephei by comparing it to that of the two neighboring stars, Epsilon and Zeta Cephei, with magnitude of 4.2 and 3.6 respectively. After data had been collected for 40 days, I compared my chart to that of Delta Cephei's typical period. I found that my observations matched with that of Delta Cephei almost perfectly. Indeed Delta Cephei's maximum magnitude was 3.6, and its minimum was 4.2. In the 40 days that I tested Delta Cephei, I charted eight periods of Delta Cephei; each period being identical to the one previous. These results led to my conclusion which is that Delta Cephei does follow a steady pattern of fluctuation from magnitude 3.6 to 4.2 in roughly a five-day cycle.