Earth and Space Science - Moon, Solar System, and Universe Review

Vocabulary practice flashcards covering eclipses, moon phases, tides, celestial models, planetary motion, comets, spectroscopy, the Big Bang, and Earth's spheres based on lecture notes.

Eclipses

Predictable alignments of the Earth, Sun, and Moon.

Solar eclipse

Occurs when the Moon moves between Earth and the Sun during the new moon phase, casting a shadow on the Earth.

Lunar eclipse

Occurs during the full moon phase when Earth moves between the Sun and the Moon and casts its shadow on the Moon.

Umbra

The innermost and darkest portion of a shadow; it is known as the Zone of Totality.

Penumbra

A partial shadow during an eclipse that is not considered a full eclipse.

Moon's orbit tilt

A $5^{\circ}$ tilt that prevents the Earth and Moon's shadows from crossing each other often, so eclipses do not occur every month.

Satellite

An object that orbits a planet, such as the Moon orbiting Earth.

Moon phases

The changing appearances of the Moon caused because it orbits Earth and is seen at different angles as it reflects light from the Sun.

Moon cycle duration

One full cycle of Moon phases takes about $29.5\,\text{days}$.

Waxing

A term used to describe when the visible part of the Moon is increasing.

Waning

A term used to describe when the visible part of the Moon is decreasing.

Crescent

A Moon phase where less than half of the visible surface is illuminated.

Gibbous

A Moon phase where more than half of the visible surface is illuminated.

Tides

Cyclic and predictable changes in ocean water levels caused by the gravitational pull of the Moon and the Sun.

Spring tides

Occur twice a month during new and full moons when the Sun and Moon are in a straight line, resulting in the highest high tides and lowest low tides.

Neap tides

Occur during $1^{st}$ and last quarter moons when the Sun, Moon, and Earth are at right angles, resulting in the smallest difference between high and low tide.

Nebula Theory

The theory stating our solar system formed about $4.6\,\text{billion}\,\text{years}$ ago from a rotating cloud of dust and gases pulled together by gravity.

Terrestrial planets

The first four planets (Mercury, Venus, Earth, and Mars) that are small, dense, and rocky.

Jovian planets

The last four planets (Jupiter, Saturn, Uranus, and Neptune) that are huge, gaseous, and less dense.

Dwarf planet

A category for celestial objects, such as Pluto, that do not fit into the Jovian or Terrestrial categories.

Geocentric Model

A model of the universe where Earth is at the center and all planets, the Sun, and stars orbit around it.

Heliocentric Model

A model where the Sun is at the center of the solar system and Earth and other planets orbit the Sun.

Rotation

The spinning or turning of an object on an imaginary line; Earth rotates once every $24\,\text{hours}$.

Revolution

The movement of one object around another object; Earth revolves around the Sun once every $365.25\,\text{days}$.

Johannes Kepler

A $17^{th}\,\text{century}$ German astronomer who mathematically determined the motions of the planets around the Sun.

Halley's Comet

A comet with a high eccentricity value of $0.97$ that is visible from Earth approximately every $76\,\text{years}$.

Comet nucleus

The irregular-shaped core of a comet made of rock, dust, and ice.

Perihelion

The point in an orbit where a body is at its closest distance to the Sun and moves the fastest.

Aphelion

The point in a planet's orbit when it is farthest from the Sun.

Sunspots

Dark, irregular areas on the Sun's surface that are cooler than the surrounding photosphere, typically by about $1500\,K$.

Astronomical Unit (AU)

The average distance between Earth and the Sun, measuring about $150\,\text{million}\,\text{kilometers}$.

Eccentricity

A measure between $0$ and $1$ of the "ovalness" of an ellipse, where values closer to $1$ are more elliptical.

Foci

Two fixed points within an ellipse used to determine the orbit's eccentricity.

Major Axis

The longer line passing through both foci in an ellipse.

Electromagnetic spectrum

The full range of radiation arranged by wavelength and frequency, including radio waves, visible light, and gamma rays.

Spectrometer

A device used by astronomers to break starlight into different colors or wavelengths.

Continuous Spectra

Emitted by a glowing solid, liquid, or high-pressure gas.

Dark-line Spectra

Also called absorption spectra, these are formed when light passes through a cooler gas which absorbs some wavelengths.

Bright-line Spectra

Also called emission spectra, these are emitted by a hot gas under low pressure.

Hubble's Law

The observational relationship showing that the farther away a galaxy is, the faster it is moving.

Big Bang theory

States the universe formed about $13.7\,\text{billion}\,\text{years}$ ago when a confined, dense, hot point exploded outwards.

Redshift

A shifting of wavelengths toward the red end of the spectrum as objects move away from the observer; main evidence for the expanding universe.

Blueshift

A shifting of wavelengths toward the blue end of the spectrum as objects move towards the observer.

Galaxy

A collection of stars, gas, and dust held together by gravity; there are over $100\,\text{billion}$ in the universe.

Hubble Space Telescope (HST)

A space telescope launched in $1990$ that observes objects as far as $10$ to $15\,\text{billion}\,\text{light}\,\text{years}$ away.

Milky Way Galaxy

The spiral galaxy where Earth is located.

Spiral galaxy

A disk-like shaped galaxy that contains many young stars.

Elliptical galaxy

A round or oval-shaped galaxy that contains mainly older stars.

Irregular galaxy

A galaxy with no defined shape containing both young and old stars.

Geosphere

Describes all rocks, minerals, and soil on Earth.

Hydrosphere

Describes all water on the Earth's surface.

Biosphere

Includes all living organisms such as plants and animals.

Atmosphere

Describes the mixture of gases surrounding Earth.

Cryosphere

Describes water in the form of ice, such as icebergs.