Chapter 32

LEARNING BASIC VOCABULARY OF ASTRONOMY WITH AI

Astronomy: the science that studies celestial bodies and phenomena that occur outside the Earth's atmosphere.

Claudius Ptolemaeus: "the father of astrology", known as Ptolemy, was a Greco-Egyptian scholar who lived in the 2nd century AD. His most famous work is the "Tetrabiblos", a treatise on astrology that greatly influenced Western astrological thought for centuries. Ptolemy is best known for his work "Almagest", in which he presented a geocentric system of the universe, where the Earth was at the center and the other celestial bodies revolved around it in circular orbits. Although his astronomical model was fundamentally wrong, he was the leading interpretation of the cosmos for over a thousand years in the Western world and contributed significantly to the field of geography with his work "Geography", which included detailed maps and descriptions of places known at the time. He systematized and popularized many of the astrological ideas that are used today.

Isaac Newton: he is a key figure in the history of astronomy due to his theory of universal gravitation and his contributions to astronomical instrumentation and mathematics; He has a very close connection with astronomy. His discoveries and theories revolutionized our understanding of the universe. One of his greatest achievements was his theory of universal gravitation, presented in his monumental work "Philosophiæ Naturalis Principia Mathematica" (Mathematical Principles of Natural Philosophy), published in 1687. This theory explained how objects attract each other due to the force of gravity, and provided a precise mathematical explanation of the movements of the planets around the Sun.

In addition to his work on gravity, Newton also made important contributions to other aspects of astronomy. For example, he developed the reflecting telescope, which uses mirrors instead of lenses to collect light, and this significantly helped in astronomical observations. Furthermore, his work in the field of differential and integral calculus provided fundamental mathematical tools for the analysis of planetary orbits and other celestial phenomena.

After Ptolemy and Newton, the history of astronomy has been filled with important figures who have contributed significantly to the field. Some of the most notable astronomers include:

Johannes Kepler: was a German astronomer and mathematician of the 16th and early 17th centuries. He is famous for his three laws of planetary motion, which describe the elliptical orbits of the planets around the Sun.

Galileo Galilei: a 16th and 17th century Italian scientist, known for his telescopic observations that confirmed Copernicus's heliocentric ideas and refuted Ptolemy's geocentric system. He also made important discoveries about the Moon, the moons of Jupiter, and the phases of Venus.

Edmond Halley: a British astronomer of the 17th and 18th centuries. He is best known for calculating the orbit of the comet he named after him, Halley's Comet, and predicting its return, which demonstrated the periodicity of comets.

William Herschel: an 18th-century British astronomer, known for discovering the planet Uranus in 1781. He also made important observations of nebulae and star clusters, and built some of the largest telescopes of his time.

Edwin Hubble: A 20th-century American astronomer, known for his discovery of the expansion of the universe and the relationship between the distance of galaxies and their recession speed, which is named after him as Hubble's Law.

Stars: are extraordinarily massive celestial bodies composed mainly of hydrogen and helium.

Through nuclear fusion in their marrows, stars generate energy in the form of light and heat; They vary in size, temperature, color and brightness; They can range from relatively small red dwarfs to massive blue supergiant’s.

Planets: they are celestial bodies that orbit around a star, like our Sun, and that do not produce their own light. They are mainly classified into two types: terrestrial (rocky) and gaseous (Jovian).

In addition to Earth, there are other planets in our solar system, including Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. They are large enough to have become round due to their own gravity and cleared their orbit of other objects.

Satellite: is a celestial body that orbits a planet. In addition to the Moon, which is Earth's natural satellite, many planets in our solar system have their own satellites, such as the moons of Jupiter and Saturn.

Galaxy: is a massive system containing stars, interstellar gas, cosmic dust and dark matter, all held together by gravity.

The Milky Way is the galaxy in which our solar system is located. Galaxies come in different shapes and sizes, from spirals like the Milky Way to ellipticals and irregulars.

Solar system: is made up of the Sun and all the objects that orbit around it, including planets, moons, asteroids, comets and other celestial bodies; It formed approximately 4.6 billion years ago from a rotating cloud of gas and dust.

Constellation: An apparent pattern of stars in the night sky, usually with associated names and myths.

Comet: A celestial body composed primarily of ice, dust, and rock, orbiting the Sun in an elliptical orbit.

Black Hole: A region of space-time where gravity is so strong that not even light can escape it.

Nebula: a cloud of interstellar gas and dust, where stars can form.

Shooting star/meteor: The flash of light produced when a space object enters a planet's atmosphere and burns up due to friction.

Orbit: The curved path that an object follows in space around another object due to gravity.

Eclipses: astronomical events in which a celestial body is completely or partially obscured due to the interposition of another celestial body.

Full Moon: Lunar phase in which the Moon is completely illuminated by the Sun and appears round from Earth.

New Moon: lunar phase in which the Moon is not visible from the Earth because it is between it and the Sun, with the illuminated side pointing towards the Sun.

Constellation: are apparent patterns of stars in the night sky that have been grouped and named by different cultures throughout history. Some famous constellations include Orion, Ursa Major and Scorpio.

Comet: They are celestial bodies composed mainly of ice, dust and rock that orbit around the Sun in elliptical areas. When a comet gets close enough to the Sun, the heat causes its components to sublimate, creating a tail of gas and dust that points away from the Sun.

WHAT ARE SOLTICES?

They are astronomical events that occur twice a year, marking the moment when the Sun reaches its highest or lowest point in the sky in relation to the celestial equator. There are two main solstices in the year: the summer solstice and the winter solstice.

Summer Solstice: Occurs around June 21 in the Northern Hemisphere and around December 21 in the Southern Hemisphere. It is the time when the Sun reaches its highest point in the sky during the year in the respective hemisphere. In the northern hemisphere, it marks the first day of summer, while in the southern hemisphere, it marks the first day of winter.

Winter Solstice: Occurs around December 21 in the Northern Hemisphere and around June 21 in the Southern Hemisphere. It is the time when the Sun reaches its lowest point in the sky during the year in the respective hemisphere. In the northern hemisphere, it marks the first day of winter, while in the southern hemisphere, it marks the first day of summer.

During the solstices, at the Earth's poles, the Sun may remain visible for a long period (summer solstice) or may not appear at all for a long period (winter solstice), due to the tilt of the Earth's axis of rotation. with respect to the plane of its orbit around the Sun. Solstices are important in many cultures as they mark the beginning of key seasons and are often celebrated with festivals and rituals.

Kepler's laws:

They are three fundamental principles formulated by the German astronomer Johannes Kepler in the 17th century. These laws describe the movement of the planets around the Sun and are fundamental to the understanding of celestial mechanics. Here is a summary of Kepler's laws and their meaning:

Kepler's First Law (Law of Orbits):

"The planets move in elliptical orbits, with the Sun at one of the focuses of the ellipse."

This law states that the orbits of the planets around the Sun are not perfect circles, as previously believed, but ellipses. The Sun is not exactly in the center of the ellipse, but at one of its foci.

Meaning: this law radically changed the conception of the universe, moving away from the geocentric model (where the Earth was considered the center of the solar system) towards a heliocentric model (where the Sun is the center and the planets orbit around it).

Kepler's Second Law (Law of Areas):

"The radius vector that joins the planet to the Sun sweeps equal areas in equal times."

This law states that a planet moves faster when it is closer to the Sun and slower when it is farther away. The speed of a planet varies such that the area swept by the radius vector linking the planet to the Sun is constant over equal periods of time.

Meaning: This law describes how the speed of a planet varies in its orbit, providing a deeper understanding of orbital dynamics.

Kepler's third law (Law of periods):

"The square of a planet's orbital period is directly proportional to the cube of the length of the semimajor axis of its orbit."

This law establishes a mathematical relationship between the orbital period (the time it takes a planet to make one complete revolution around the Sun) and the average distance of the planet from the Sun.

Meaning: This law allows you to calculate the distance of a planet from the Sun if its orbital period is known, or vice versa. It provides a quantitative relationship between the distance and the period of the planets in their orbits.

Kepler's laws laid the foundation for the scientific revolution in astronomical thought and were fundamental to the later development of Isaac Newton's theory of universal gravitation.