Moon Phases #RockinReview

Waxing/Waning Moon

In the northern hemisphere, if the left side of the moon is dark then the light part is growing, and the moon is referred to as waxing(moving toward a full moon). If the right side of the moon is dark then the light part is shrinking, and the moon is referred to as waning (past full and moving toward a new moon).

Gibbous Moon

A gibbous is when the Moon is more than half full, but not quite fully illuminated, when you look at it from the perspective of Earth.

Crescent Moon

A crescent moon is part way between a half moon and a new moon, or between a new moon and a half moon

Lunar Cycle

A Lunar Cycle is a cycle of 235 synodic months, very nearly equal to 19 years, after which the new moon occurs on the same day of the year as at the beginning of the cycle with perhaps a shift of one day, depending on the number of leap years in the cycle.

Seasons #eclipses

"Seasons" are each of the four divisions of the year (spring, summer, autumn, and winter) marked by particular weather patterns and daylight hours, resulting from the earth's changing position with regard to the sun.

Nicolaus Copernicus (1473-1543)

Born on Feb. 19, 1473, in Poland, Copernicus traveled to Italy at the age of 18 to attend college, where he prepared for a career in the church. As part of his education, he studied astrology — reading the stars to learn about future events — because at the time it was felt important for priests and doctors. Astronomy, the motion of heavenly bodies, was an important element of this. One of the glaring mathematical problems with this model was that the planets, on occasion, would travel backward across the sky over several nights of observation. Astronomers called this retrograde motion. To account for it, the current model, based on the Greek astronomer and mathematician Ptolemy's view, incorporated a number of circles within circles — epicycles — inside of a planet's path. Some planets required as many as seven circles, creating a cumbersome model many felt was too complicated to have naturally occurred. In 1514, Copernicus distributed a handwritten book to his friends that set out his view of the universe. In it, he proposed that the center of the universe was not Earth, but that the sun lay near it. He also suggested that Earth's rotation accounted for the rise and setting of the sun, the movement of the stars, and that the cycle of seasons was caused by Earth's revolutions around it. Finally, he (correctly) proposed that Earth's motion through space caused the retrograde motion of the planets across the night sky (planets sometimes move in the same directions as stars, slowly across the sky from night to night, but sometimes they move in the opposite, or retrograde, direction). t wasn't until he lay on his deathbed at the age of 70 that Copernicus published his book, De Revolutionibus Orbium Coelestium ("On the Revolutions of the Heavenly Spheres"). In it, Copernicus established that the planets orbited the sun rather than the Earth. He lay out his model of the solar system and the path of the planets. Although Copernicus' model changed the layout of the universe, it still had its faults. For one thing, Copernicus held to the classical idea that the planets traveled in perfect circles. It wasn't until the 1600s that Johannes Kepler proposed the orbits were instead ellipses. As such, Copernicus' model featured the same epicycles that marred in Ptolemy's work, although there were fewer. Copernicus' ideas, published only two months before he died, took nearly a hundred years to seriously take hold. When Galileo Galilei claimed in 1632 that Earth orbited the sun, building upon the Polish astronomer's work, he found himself under house arrest for committing heresy against the Catholic church. Despite this, the observations of the universe proved the two men correct in their understanding of the motion of celestial bodies. Today, we call the model of the solar system, in which the planets orbit the sun, a heliocentric or Copernican model.

Why Do We Have Seasons?

We have seasons because the Earth’s axis is tilted. Consider any globe you’ve ever used, and you’ll see that instead of being straight up and down, the Earth is at a tilt of 23.5-degrees. The Earth’s North Pole is actually pointed towards Polaris, the North Star, and the south pole towards the constellation of Octans. At any point during its orbit, the Earth is always pointed the same direction. For six months of the year, the Northern hemisphere is tilted towards the Sun, while the Southern hemisphere is tilted away. For the next six months, the situation is reversed. Whichever hemisphere is tilted towards the Sun experiences more energy, and warms up, while the hemisphere tilted away receives less energy and cools down.

Why Do We Have Day and Night?

We have day and night because the Earth rotates. It spins on its axis, which is an imaginary line passing through the North and South Poles. The Earth spins slowly all the time, but we don't feel any movement because it turns smoothly and at the same speed.


The time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20).


Either of the two times in the year, the summer solstice and the winter solstice, when the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days.

Plate Tectonics #platetectonics

Alfred Wegener

Plate Tectonics #platetectonics

Alfred Wegener

Convergent, Divergent, and Transform Boundaries

Convergent Boundaries: a convergent boundary, also known as a destructive plate boundary because of subduction, is an actively deforming region where two or more tectonic plates or fragments of the lithosphere move toward one another and collide.

Divergent Boundary: a divergent boundary or divergent plate boundary; also known as a constructive boundary or an extensional boundary is a linear feature that exists between two tectonic plates that are moving away from each other.

Transform Boundaries: A transform boundary or conservative boundary is where two of the floats - two tectonic plates - side alongside each other. When this happens, the scraping of the two plates causes earthquakes.

Alfred Lothar Wegener (November 1, 1880 – November 1930) was a German polar researcher, geophysicist and meteorologist. During his lifetime he was primarily known for his achievements in meteorology and as a pioneer of polar research, but today he is most remembered for advancing the theory of continental drift(Kontinentalverschiebung) in 1912, which hypothesized that the continents were slowly drifting around the Earth. His hypothesis was controversial and not widely accepted until the 1950s, when numerous discoveries such as palaeomagnetism provided strong support for continental drift, and thereby a substantial basis for today's model of plate tectonics. Wegener was involved in several expeditions to Greenland to study polar air circulation before the existence of the jet stream was accepted. Expedition participants made many meteorological observations and achieved the first-ever overwintering on the inland Greenland ice sheet as well as the first-ever boring of ice cores on a moving Arctic glacier.

Washington Plates

The Juan De Fuca Plate lies right off the coast of Washington. This plate connects with the North American Plate right where the Cascade Mountains are. The Cascade Mountains were formed when the Juan De Fuca Plate subducted under the North American plate, subsequently making the North American Plate raise on the boundary.

Convection Currents in Plate Tectonics

Convection currents play a large part in plate tectonics. Convection Currents in the Mantle draw a plate down when the cold air sinks (subduction) and pushes up the overlapping plate when the hot air rises.

Rift and Subduction Zones

Rift Zone: A rift zone is a feature of volcanoes, especially shield volcanoes, in which a linear series of fissures in the volcanic edifice allows lava to be erupted from the volcano's flank rather than its summit.

Subduction Zone: A subduction zone is the biggest smash-up on Earth, marking the collision between two of the planet's tectonic plates, the pieces of crust that slowly move across the surface over millions of years. When two tectonic plates meet, one may slide underneath the other, curving down into the mantle.

Channeled Scablands

The Channeled Scablands are a barren, relatively soil-free landscape in eastern Washington, scoured clean by a flood unleashed when a large glacial lake drained. They are a geologically unique erosional feature in the U.S. state of Washington. They were created by the cataclysmic Missoula Floods that swept periodically across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. Geologist J Harlen Bretz coined the term in a series of papers in the 1920s. Debate over the origin of the Scablands raged for four decades and is one of the great debates in the history of earth science. The Scablands are also important to planetary scientists as perhaps the best terrestrial analog for the Martian outflow channels.