In the April 2018 issue of "TPT," Joseph Amato presented an analysis of intercontinental ballistic missile (ICBM) trajectories as applied to recent test launches from North Korea. Using properties of their elliptical paths, he derived relationships between launch velocity, elevation angle, and maximum range. However, this approach cannot…

The Search for Exoplanets is an interactive computer simulation, the product of a collaboration between the Departments of Physics and Astronomy and Computer Science at Purdue University. Our goal was to create a computer simulation that would introduce students to scientific principles, research methodology, and analysis of data with which…

A planetarium is an invaluable tool for teaching introductory astronomy, but one that few astronomy educators have ready access to. Here we describe a do-it-yourself planetarium that can be built with modest funding. There have been other planetarium construction projects described in the literature and online, most of which use cardboard to make…

Throughout time people have been measuring the rising and setting positions of celestial objects with respect to the horizon. The motivation for this paper is to provide a link between mathematical and observational approximations for the Sun's declination (angular distance from the celestial equator). One source had students do an experiment with…

Gravitational lensing is an interesting phenomenon in astronomy and is most typically given rise to by galaxies. The majority of the matter in a galaxy is thought to be dark matter, and the galactic gravitational lensing effect is mainly caused by dark matter halos. In gravitational lensing-related demonstrations in physics education, the feet of…

During the 17th century the idea of an orbiting and rotating Earth became increasingly popular, but opponents of this view continued to point out that the theory had observable consequences that had never, in fact, been observed. Why, for instance, had astronomers failed to detect the annual parallax of the stars that "must" occur if…

Simulations of physical systems are widely available online, with no cost, and are ready to be used in our classrooms. Such simulations offer an accessible tool that can be used for a range of interactive learning activities. The Jovian Moons Apple allows the user to track the position of Jupiter's four Galilean moons with a variety of…