Grade 10 Science: Space & Astrophysics Vocabulary

Vocabulary flashcards covering key concepts, units, methods, and phenomena from the Grade 10 Space and Astrophysics review notes.

Astronomical Unit (AU)

A standard unit of astronomical measurement defined as the average distance from Earth to the Sun, equal to approximately $150\,\text{million kilometers}$.

Redshift

The phenomenon discovered by Edwin Hubble where light from receding distant galaxies is stretched toward longer, redder wavelengths as space expands.

Nebular Hypothesis

The model describing solar system formation, which notes that heavy metals present in our nebula were likely collected from a nearby supernova explosion.

Planetesimals

Small, rocky or icy bodies formed by the clumping of dust particles in the early protoplanetary disk.

Initial Mass

The single property of a star that determines its entire lifecycle path and final evolutionary state.

Supernova Explosion

A stellar explosion during which heavy elements beyond iron, such as gold, lead, and uranium, are naturally synthesized.

Transit Method

An exoplanet detection technique that measures the periodic dimming of a star's brightness as a planet passes directly between the star and the observer.

Habitable Zone (Goldilocks Zone)

The orbital region around a star where temperatures permit the existence of liquid water on a rocky planet's surface.

Biosignatures

Chemical indicators in an exoplanet's atmosphere, such as oxygen and methane, that suggest biological activity.

Parsec

A standard unit of astronomical distance equal to approximately $3.26\,\text{light years}$, defined by a parallax angle shift of one arcsecond.

Nuclear Fusion

The fundamental process occurring in stellar cores that transforms hydrogen protons into helium nuclei while converting mass into energy according to $E = mc^2$.

Neutron Star

An extremely dense stellar remnant composed almost entirely of neutrons, where a single teaspoon of material weighs millions of tons.

Main Sequence

A continuous band running diagonally across the Hertzsprung-Russell (H-R) diagram, representing stars actively fusing hydrogen in their cores while balancing gravitational collapse against thermal and radiation pressure.

Light Year

The distance light travels through a vacuum in one Earth year, equal to approximately $9.46\,\text{trillion km}$.

Protoplanetary Disk

A spinning, flattened disk of gas and dust surrounding a newly formed protostar.

Habitable Worlds Observatory

A planned space observatory designed to directly image exoplanets and search for biosignatures.

Event Horizon

The theoretical boundary of a black hole where the escape velocity equals the speed of light.

White Dwarf

A small, collapsed star remnant left behind after a low-to-medium mass star sheds its outer layers.

High-Mass Star Threshold

Stars with an initial mass greater than $8\,\text{solar masses}$ that undergo a distinct lifecycle from protostar to supernova, leaving behind a neutron star or black hole.