During the early decades of the 18th century, Newtonian physics was still new. Much effort was expended in testing its validity. One arena in which evidence could be found was the shape of Earth. Was it perfectly spherical? On the observational side there were two hints. In 1671 Jean Richer had measured the rate of ticking of a pendulum clock near…

Owing to the presence of the Coriolis effect, the rotation of Earth has a multitude of surprising consequences that make the mechanics of the atmosphere or the oceans different from that of a fluid in a container. Since the Coriolis effect also captures the imagination of screenwriters, contributing to the continual exposure of students to bogus…

The acceleration of gravity in Earth's interior is determined by the density distribution in Earth. A remarkable result is that the acceleration is approximately constant all over the mantle, which amounts to about 84% of Earth's volume. This result can be explained by a simple two-layer model of Earth, showing that the constancy of the…

In this work we describe a teaching proposal to calculate the eccentricity of the Moon's trajectory by applying a geometrical technique. The values of the ratios between the Earth-Moon distance and the diameter of the Moon at apogee and at perigee were calculated from a kinematic model associated with a geometrical technique of image analysis. The…

I had been sitting in a coffee shop in Reykjavik, Iceland, cycling through my photographs of the aurora borealis from the night before in Njardvik, when a man at the next table struck up a conversation. Recognizing his familial ties to the location in my photographs, he began to share stories that his grandfather told him as a child regarding the…

The characteristics of the inner layer of the atmosphere, the troposphere, are determinant for Earth's life. In this experience we explore the first hundreds of meters using a smartphone mounted on a quadcopter. Both the altitude and the pressure are obtained using the smartphone's sensors. We complement these measures with data collected from the…

In the school year 2012-2013 about 50 students (Fig. 1), managed by mentors (teachers from the middle school Gimnazija Vic in Ljubljana, Slovenia) created an atmospheric probe and launched it into an altitude of more than 30 km above Earth's surface. The aim of this "space expedition" was to take pictures of Earth and to measure how air…

Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

This is a companion to our previous paper in which we give a published example, based primarily on Perry's work, of a graph of ln "y" versus "t" when "y" is an exponential function of "t". This work led us to the idea that Lord Kelvin's (William Thomson's) estimate of the Earth's age was…

While on a vacation flight from Hawaii to California, I observed sunset occurring on clouds far below. The view triggered a vague memory about a fun article 1 published more than three decades earlier on the topic of "Doubling Your Sunsets." Simple observations from my flight made it possible to compute the Earth's radius.

The 5000-year-old remains of Stonehenge, in England, testify to humankind's reverence for the stars. Humans hauled four-ton stones from as far away as 240 km to make these monuments. They are the remains of a larger structure used for religious purposes and to predict astronomical events such as solstices, equinoxes, and perhaps even eclipses, an…

Heat transfer is widely taught in secondary Earth science and physics. Researchers have identified many misconceptions related to heat and temperature. These misconceptions primarily stem from hunches developed in everyday life (though the confusions in terminology often worsen them). Interactive computer simulations that visualize thermal energy,…

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…

Around 240 B.C., Eratosthenes made what is considered to be the most famous and accurate of the ancient measurements of the circumference of the Earth. It was accomplished by making "presumably simultaneous" measurements of the angles of the shadows cast by a vertical stick at Syene (today known as Aswan) and another at Alexandria, at noon on the…

November 10, 2015, marked the 40th anniversary of the sinking of the "S. S. Edmund Fitzgerald," a Great Lakes bulk cargo freighter that suddenly and mysteriously sank during a severe winter storm on Lake Superior. A year after the sinking, Canadian folksinger Gordon Lightfoot wrote and recorded the ballad "The Wreck of the 'Edmund…