PSY 124 FINAL (Terms to Know)

Asteroid belt

A region centered on the sun, and spanning the space between the orbits of Mars and Jupiter. It contains many asteroids.

Cambrian explosion

An event where the number and diversity of species exploded (500 million years ago).

Carbonaceous chondrites

Rare, primitive meteorites rich in carbon, water, and organic compounds. They are crucial for studying the early solar system.

Chromosphere

Layer of the Sun’s atmosphere above the photosphere, visible during solar eclipses.

Convective zone

Interior layer located between the radiative zone and the photosphere, where energy is transported by rising hot gas and sinking cool gas.

Corona

The outermost layer of the Sun’s atmosphere. Extremely hot and visible during eclipses.

Coronal mass ejections

Massive bursts of plasma and magnetic fields from the Sun's corona

Cryovolcanism

A type of cold volcanic activity occurring on icy, outer solar system bodies where, instead of molten rock, volcanoes erupt "cryomagma"

Cyanobacteria

The first organisms known to have produced oxygen 2.5 billion years ago. Produced O2 and replaced greenhouse gases, the atmosphere cooled.

Dwarf planets

Round objects that orbit the Sun but have not cleared their orbits of smaller bodies

Eclipsing binary

Star systems where two stars orbit in a plane aligned with Earth, causing periodic dips in total brightness as they pass in front of one another

Extremophiles

An organism that is able to live in extreme environments

Helioseismology

The study of the Sun's interior structure, rotation, and dynamics by analyzing sound waves (p-modes) and surface oscillations

Heredity

Exploration of the origins of life and its distribution in the universe

Hertzsprung-Russell Diagram

Graph comparing stellar luminosity vs. temperature.

Hot, luminous stars lie in the upper left.

Large, luminous stars lie in the upper right.

Small, faint, cool stars lie in the lower right.

Kuiper belt

A region of icy bodies and dwarf planets—including Pluto—in the outer solar system

Main Sequence

The longest, most stable phase in a star's life, where it fuses hydrogen into helium in its core

A star’s mass is what determines its position on the main sequence:

• Less massive stars lie in the lower right.

• More massive stars lie in the upper left.

Metal (M-type) asteroids

A rare, nickel-iron-rich celestial body, making up about 8%–10% of main-belt asteroids

Nutation

A small periodic "wobble" in the Earth’s axial precession, causing a slight

±0.025 degree variation in its tilt over an 18-year cycle.

Natural selection

The primary mechanism of evolution where organisms better adapted to their environment tend to survive and produce more offspring

Neutrino

The most abundant particles in the universe. They carry no charge, meaning they do not get absorbed or altered in transit.

Because they barely interact with matter, they are notoriously difficult to detect.

Oort cloud

A theoretical, vast spherical shell surrounding the Solar System, composed of trillions of icy, comet-like objects

Orbital resonance

An occurrence when orbiting bodies (planets, moons, or asteroids) exert periodic gravitational influences on each other.

Parallax

An apparent shift in a star’s position used to measure distance.

Photosphere

The visible surface of the Sun.

Phylogenetic tree

Branching diagrams representing hypotheses about the evolutionary relationships among species or groups.

Radiative zone

Solar layer where energy moves outward via radiation (photon diffusion).

Red Giant

A luminous, low-to-intermediate mass star in the late stage of stellar evolution. They are bloated, with an expanding outer atmosphere and a cool, reddish surface

Shepherd moons

Small natural satellites that orbit near the edges of planetary rings. They prevent rings from spreading out and dissipating

Solar prominence

Large, stable structures of cool, dense plasma extending from the Sun’s surface.

Solar maximum

Period of peak sunspot activity in the Sun’s cycle.

Solar wind

Stream of charged particles flowing from the Sun.

Spectroscopic binary

Binary star detected through Doppler shifts in spectral lines.

Stony (S-type) asteroids

The second most common type of asteroid. Primarily composed of silicate minerals (like olivine and pyroxene) and nickel-iron, they are found mostly in the inner asteroid belt.

Sun spots

Cooler, darker areas on the Sun's surface (photosphere) caused by intense magnetic field activity that inhibits heat transfer

Thermonuclear Fusion

The process where light atomic nuclei (primarily hydrogen) combine to form heavier nuclei (like helium) under extreme temperature and pressure inside stars

White Dwarf

The extremely dense core left behind after a low-to-medium mass star (like our Sun) has exhausted its nuclear fuel and expelled its outer layers