The change in light waves to longer wavelengths as objects in space move away from the observer. Evidence for expanding universe. Related to Doppler effect.

The opposite of redshift, showing objects moving closer.

The change in wave frequency due to relative motion, explaining redshift/blue shift.

The observation that galaxies are receding from us at speeds proportional to their distance.

A mysterious force accelerating the universe's expansion.

A period of rapid, exponential expansion of the early universe.

Faint, uniform microwave radiation, the cooled afterglow of the Big Bang.

The leading model for the universe's origin from a hot, dense state.

A particle of light.

Extremely large or related to astronomy. Often used to describe something vast or related to space science.

Related to the sky or outer space. Includes stars, planets, and other heavenly bodies.

The study of the interaction between matter and electromagnetic radiation. Analyzes light spectrum Identifies elements in stars.

The change in light waves to longer wavelengths as objects in space move away from the observer. Evidence for expanding universe. Related to Doppler effect.

A point in space where density and gravity become infinite, such as the center of a black hole.

A model of the universe where the sun is at the center.

A model of the universe where Earth is at the center.

The path one object takes as it revolves around another object in space. Circular or elliptical path, involves gravitational forces.

The study of the origin, evolution, and eventual fate of the universe. Includes Big Bang theory - Examines universe's structure.

The lighter part of a shadow where only some light is blocked. Occurs during eclipses. Found on the edges of the shadow. People in the penumbra during a solar eclipse experience a partial eclipse.

The action of moving around something in a path that takes a full circle. Involves a complete orbit. Takes place in a regular cycle.

When the moon moves between the Earth and the sun, blocking sunlight and casting a shadow on Earth. Occurs during the new moon phase. Only visible from specific areas on Earth.

When day and night are equal in length due to the sun being directly over the equator. Happens twice a year (spring and fall). Marks a change in seasons.

When the sun reaches its highest or lowest point in the sky, creating the longest or shortest day of the year.

When the Earth moves between the sun and the moon, casting a shadow on the moon. Occurs during the full moon phase. Visible from anywhere on Earth where it's night.

Relating to an axis, or an imaginary line through the center of a rotating object. Earth's axial tilt is 23.5°. Causes seasons and day/night.

A type of tide that occurs when the gravitational forces of the moon and sun align, creating the greatest difference between high and low tides. Happens during the new moon and full moon phases.

The type of tide that occurs when the gravitational forces of the moon and sun are at right angles, causing the least difference between high and low tides. Happens during the first and last quarter moon phases. Gravitational forces from the moon and sun partially cancel each other out.

Related to spring or occurring during spring. Refers to events or characteristics of spring. Often associated with growth, renewal, and warmth.

The darkest part of a shadow where all light from a source is blocked. Occurs during eclipses. Found in the center of the shadow. People in the umbra during a solar eclipse experience a total eclipse.

A series of events that repeat in the same order. Predictable and continuous. Includes events like moon phases, seasons, and tides.

Related to autumn or occurring during autumn. Refers to events or characteristics of fall. Often associated with cooler temperatures, shorter days, and falling leaves.