Astronomy and Space Science

Vocabulary practice flashcards based on the Astronomy and Space Science Quiz lecture notes covering planetary science, cosmology, stellar evolution, and space exploration.

Cosmology

The branch of science that studies the origin, structure, and evolution of the universe as a whole.

Edwin Hubble

The scientist regarded as the "Father of Cosmology" whose observations revealed that galaxies lie beyond the Milky Way and are receding.

Redshift

The stretching of light from distant galaxies to longer, redder wavelengths, which serves as direct evidence that the universe is still expanding.

Cosmic Microwave Background Radiation (CMBR)

The cooled leftover heat and radiation from the early universe, released about $380{,}000\text{ years}$ after the Big Bang.

Stellar Core

The central region of a star where temperatures and pressures are sufficiently high for hydrogen nuclei to undergo nuclear fusion into helium.

Hertzsprung-Russell Diagram (H-R Diagram)

An astronomical chart that plots a star's surface temperature (or spectral class) against its brightness (luminosity).

Type II Supernova

A core-collapse explosion that occurs when a high-mass star exhausts its nuclear fuel.

Barred Spiral Galaxy

The structural classification of the Milky Way galaxy, characterized by a central stellar bar surrounded by spiral arms.

Protoplanet Nebular Model

The most widely accepted theory for the origin of the solar system, asserting that the Sun and planets coalesced from a rotating, collapsing cloud of gas and dust.

Mercury

The innermost planet of the solar system, which has the shortest orbital period at approximately $88\text{ Earth days}$.

Johannes Kepler

The astronomer who refined the heliocentric model by proposing that planets travel in elliptical orbits rather than perfect circles.

Retrograde Rotation

The clockwise or backward rotation of a planet relative to the majority of celestial bodies, exhibited by Venus and Uranus.

Ceres

The closest dwarf planet to the Sun, located within the asteroid belt between Mars and Jupiter, which was formerly classified as the largest asteroid.

Sputnik 1

The first artificial satellite to orbit Earth, launched by the Soviet Union on October 4, 1957, marking the beginning of the space age.

Uranus

A planet that rotates on its side due to an axial tilt of about $98^\circ$ and displays a blue-green color because methane in its atmosphere absorbs red light.

Venus's Greenhouse Effect

An extreme trapping of thermal energy caused by a thick carbon dioxide atmosphere, resulting in surface temperatures of about $465^\circ\text{C}$.

Dwarf Planet

A celestial body orbiting the Sun with sufficient mass for self-gravity to achieve a nearly round shape, but which has not cleared the neighborhood around its orbit.

Geocentric Model

Ptolemy's planetary model asserting that Earth is stationary at the center of the universe while all other bodies revolve around it.

Perihelion

The orbital position closest to the Sun where, according to Kepler's Second Law, a planet moves at its maximum speed.

Iron Oxide

The compound coating the Martian surface whose reddish dust gives Mars the nickname "Red Planet."

Jupiter

The planet with the fastest rotation rate in the solar system, finishing one rotation in under $10\text{ hours}$.

Saturn

The planet with the lowest mean density in the solar system ($0.69\,\text{g/cm}^3$), making it less dense than water.

New Horizons

The NASA spacecraft that executed the first historic flyby of Pluto on July 14, 2015.

Comet Period Classification

The distinction separating short-period comets from long-period comets based on their place of origin (the Kuiper Belt versus the Oort Cloud).

Sunspots

Dark, cooler areas visible on the Sun's surface generated by concentrations of intense magnetic activity.

Lunar Surface Gravity

The gravitational force on the Moon, equal to approximately $\frac{1}{6}$ of Earth's gravity (about $1.62\,\text{m/s}^2$ compared to Earth's $9.8\,\text{m/s}^2$).

Lunar Craters

Depressions on the Moon's surface produced primarily by meteoroid and asteroid impacts, preserved due to an absence of atmospheric weathering.

Valentina Tereshkova

The first woman to fly into space, completing her historic orbital flight on Vostok 6 in 1963.

Georges Lemaitre

The Belgian priest and physicist who first proposed in 1931 that the universe expanded from a single "primeval atom."

Alexei Leonov

The Soviet cosmonaut who performed the first spacewalk outside his spacecraft during the Voskhod 2 mission in 1965, lasting $12\text{ minutes}$.

Stellar Mass

The fundamental physical property that governs a star's core pressure, fusion rate, life expectancy, and ultimate evolutionary fate.

Great Dark Spot

A large atmospheric storm system characterized by intense winds observed on Neptune by Voyager 2.

Auroras

Polar atmospheric light displays caused by charged solar wind particles interacting with gases in Earth's atmosphere.