Meteorology and Celestial Phenomena
Definitions:
Meteor: A metallic or stony object that burns up as it passes through the Earth’s atmosphere and appears to be a "shooting star".
Meteoroid: Small, interplanetary metallic and stony objects in space before they encounter the Earth.
Meteorite: A metallic or stony object from the solar system that strikes the Earth’s surface.
Light Year: A measurement of distance in astronomy, specifically the distance light travels in one year.
Moon Characteristics
Far Side: The hidden side of the Moon, never seen from Earth due to tidal locking.
Near Side: The side of the Moon that is visible and faces the Earth.
Dark Side: There is no dark side of the Moon; the term refers to the far side due to its lack of visibility.
Highlands: Light-colored rocky surfaces on the Moon.
Maria: Large, dark, flat areas on the Moon believed to be craters formed by large impacts from space that then filled with volcanic lava.
Craters: Circular depressions on the surface of the Moon caused by the impact of meteoroids.
Models of the Universe
Heliocentric Model: A model of the solar system that places the Sun at its center.
Geocentric Model: An outdated theory that placed the Earth at the center of the solar system.
Astrology vs. Astronomy
Astrology: The study of how the positions of planets and stars at the time of an individual's birth may affect personality and/or future.
Astronomy: The scientific study of the universe beyond the Earth's atmosphere.
Characteristics of Terrestrial Planets
Planets: Mercury, Venus, Earth, Mars.
Physical and Chemical Characteristics: These four inner planets resemble those of Earth, are relatively small in size and mass, composed mainly of rocky materials and metals, and have cores predominantly of iron and nickel.
Surface: All have dense, solid surfaces.
Characteristics of Jovian Planets
Planets: Jupiter, Saturn, Uranus, Neptune.
Similarities: Exceptionally large, exhibit strong magnetic fields, have multiple moons and ring systems, are located far from the Sun with wide separations in orbits.
Composition: Made predominantly of hydrogen and helium gases and characterized by low densities.
Characteristics of Dwarf Planets
Examples of Dwarf Planets: Pluto, Ceres, Eris, Haumea, Makemake.
Criteria: Does not orbit about the Sun directly; lacks sufficient mass for self-gravity to form a nearly round shape; not the dominant body within its orbit.
Note: Pluto is not classified as a dwarf planet because it is not gravitationally dominant enough to clear the neighborhood around its orbit. Ceres resides in the asteroid belt between Mars and Jupiter.
Coordinate Features
Cartesian Coordinate System: A two-dimensional coordinate system where two number lines are perpendicular to each other with the origin assigned at their intersection. A third dimension can be introduced for three-dimensional applications.
Solar Position and Energy Distribution
Understanding Solar Height: The effective energy incident on the surface of a local area changes with the height of the Sun in the sky.
A higher Sun (closer to 90 degrees) concentrates energy over a smaller area, while a lower Sun spreads the same energy over a larger area, reducing heat intensity.
Meteorological Seasonal Variation
Primary Cause: Seasonal variations are primarily due to the tilt of the Earth’s axis relative to its orbit around the Sun.
Incorrect Justifications: It is a common misconception that seasonal variations occur because the Earth is closer to the Sun in summer and farther away in winter (FALSE; the elliptical orbit does not significantly affect seasons). During winter in the Northern Hemisphere, Earth is actually closest to the Sun. Similarly, the Earth's rotation affects day and night, not seasonal cycles.
Tilt of Earth's Axis: The tilt is responsible for seasonal variations, and the orbit is slightly elliptical.
Important Seasonal Dates
Vernal Equinox: Occurs around March 21, marking the point where the Sun crosses the celestial equator from south to north, beginning of spring in the Northern Hemisphere.
Autumnal Equinox: Occurs around September 22, where the Sun crosses the celestial equator from north to south, marking the beginning of fall in the Northern Hemisphere.
Winter Solstice: Around December 22, this is when the Sun is farthest south, marking the beginning of winter for the Northern Hemisphere.
Summer Solstice: Around June 21, the Sun is farthest north, signifying the start of summer in the Northern Hemisphere.
Asteroids
Definition: Asteroids are numbered objects circling the Sun, generally found in the asteroid belt between Mars and Jupiter. They are sometimes referred to as minor planets.
Characteristics of Comets
Definition: Relatively small celestial objects composed of rock, dust, and ice that orbit the Sun in highly elliptical paths.
Four Parts:
A rocky, icy nucleus.
A gas and dust coma.
Voluminous dust and ion tails.
A spherical hydrogen cloud.
Composition of the Sun
Photosphere: The bright, visible "surface" of the Sun.
Chromosphere: A layer of very hot gases located just above the photosphere.
Corona: The outer solar atmosphere extending from the Sun's surface.
Sun's Energy Source
Nature of the Sun: The Sun is a star comprised of self-luminous hot gas.
Source of Energy: The Sun generates energy through the process of nuclear fusion.
Nuclear Fusion: The process of fusing hydrogen nuclei into helium within its core, releasing vast amounts of energy that fuels its light and heat.
Types of Galaxies
Definition of Galaxy: An extremely large collection of stars bound together by mutual gravitational attraction.
Four Types of Galaxies:
Elliptical Galaxy: Stars clustered together in a spherical or ellipsoidal shape without curved arms.
Normal Spiral Galaxy: Stars congregate in a nuclear bulge, with a disk consisting of arms spiraling outward.
Barred Spiral Galaxy: Contains a broad bar extending outward from sides of the nuclear bulge prior to the outer arms curving.
Irregular Galaxy: Lacks any regular geometric shape.
Eclipses
Types of Eclipses:
Lunar Eclipse: Occurs when the Earth’s umbral (dark) shadow completely covers the Moon.
Solar Eclipse: Happens when the Sun is entirely blocked, as observed by someone in the umbra.
Eclipse Definition: The blocking of light from one celestial body by another; involve the concepts of umbra (total darkness) and penumbra (partial darkness).
Moon Rotation and Orbit
Rotation and Revolution Period: The Moon rotates on its axis, revolves around, and orbits Earth in approximately 27.3 Earth days.
Rotation: The act of turning or spinning of an object about its own internal axis.
Revolution: The movement of one object around another.
Vocabulary
Celestial Sphere: An apparent sphere in the sky where all stars seem to be located.
Celestial Equator: The extension of the Earth’s equator onto the celestial sphere.
North Celestial Pole: The point in the northern sky where Earth's axis of rotation intersects the celestial sphere, directly above Earth's North Pole.
Comet: A small object made of rock, dust, and ice, revolving around the Sun in a highly elliptical orbit.
Retrograde Motion: Orbital or rotational motion opposite the primary direction (clockwise in the solar system).
Ecliptic: The path traced by the Sun along the celestial sphere annually.
Black Hole: An object so dense that even light cannot escape its surface due to a highly intense gravitational field.
Tides: The periodic rise and fall of water levels in large bodies of water.
Albedo: The fraction of incident sunlight reflected by a celestial object.
Prograde Motion: Orbital or rotational motion in the primary direction (counterclockwise as viewed from above the Earth's North Pole).
Solar System: A complex system of moving masses held together by gravitational forces, consisting of the Sun, eight major planets, their satellites, dwarf planets, asteroids, comets, meteoroids, and interplanetary dust.
Zodiac: An ancient system dividing the sky's ecliptic path into 12 equal zones based on constellations.
Law of Elliptical Orbits: States that all planets move in elliptical orbits around the Sun, with the Sun at one focus of the ellipse.
Universe: The totality of all matter, energy, and space.
Earth Location Coordinates
Latitude: The angular measurement in degrees north or south of the equator, measured from the center of the Earth relative to the equator. Lines of equal latitude are circles drawn on the Earth’s surface, parallel to the equator.
Longitude: Imaginary lines drawn from the North to South poles and perpendicular to the equator, referred to as meridians. The angular measurement in degrees is east or west of the reference meridian, which is the prime meridian at Greenwich, England; the maximum value is 180 degrees East or West.
Time Measurements
Solar Day: The elapsed time between successive crossings of the same meridian by the Sun, with an average solar day equal to 24 hours. To complete a solar day, the Earth must rotate slightly more than 360 degrees.
Sidereal Day: The time between two successive crossings of the same meridian by a star other than the Sun. A sidereal day indicates the time interval points toward a distant star, being parallel due to great distance.
A.M. (Ante Meridiem): Refers to the time before noon.
P.M. (Post Meridiem): Refers to the time after noon.
Greenwich Mean Time (GMT): The time at the central prime meridian or Greenwich meridian (0 degrees longitude).